Lol! I used to be easy, too. I've become so disenchanted with magazines and performance books, that I approach all of that info with a critical eye. Like, oh I don't know, rocker geometry perhaps. As most know, I take a different approach there as well.
lifter galley crossover tube
- Thread starter douglas340
- Start date
-
Rapid Robert
Well-Known Member
speaking of rocker geometry, a guy on Moparts just posted that people there should call Mike at B3 to get the straight scoup on that subject & that he couldn't tell a lie if there was a gun to his head! Direct quote.
Yeah, I know who that is, and so do you. Just by a different FABO name. I'll let him decide if he wants to be unmasked, lol.
Nope, no lie with a gun to my head, but if they aimed at something important, I might let a little white lie slip.
Duane
Well-Known Member
Well ok between the two post about creating a low pressure point being mentioned do we have an agreement that you can have full oil pressure at your gauge and certain areas starving for oil because of low pressure?
I may be mistaken but I do not believe that I gave velocity as the cause of the 2&4 mains.
You are correct there is no point in grooving the cam grooves as this hurts the main bearings. As I said most cam manufacturers no longer do this. It was another tried in the past experiment that does not help, just like cross drilling.
I believe that older Chevy small blocks were fed from a center galley that was not used to feed the lifters and that this galley was dead ended at the end so no velocity issues there.
In a previous post I mentioned that the plug being added at the end of the galley is not discussed enough.
The cross over tube method and the tubing the block method both have in common adding a plug to dead end the system. The only difference is where the plug is. One is over top of #1 main feed passage and the other is in front of it with the #1 passage blocked from the #1 main bearing. This plug also helps stop the velocity.
You are correct that the rocker oiling mod by itself does not make the block into a priority main oil system. But it is a step towards it.
It is my understanding that an "R" block does not come with any feed passages drilled to the lifters so you do not have to tube the block.
Lifter oiling is always optional on a full race motor.
Regarding the straight shot oiling I also mentioned that the location of the oil holes has been refined. Not that it was new.
There is a trend now towards oiling the rockers with external lines tapped into the main galley. I believe Jim sizilgys jumper tube mod accomplishes the same thing.
Duane
Well-Known Member
T56MaxTorq
Well-Known Member
You will always have different pressures throughout the entire system. The gauge will see the highest pressure because only #5 is being fed oil (if I'm not mistaken) before the all clearances start slowly bleeding that pressure. If you were to take a reading at the drivers rocker shaft it will be less than gauge pressure.
Which makes me ask a question for the original oil tube mod. Since the oil is flowing so fast past #4 and the tube mod slows this force down, why not just run an oil cooler out of the oil pressure sensor port that would bleed this excess flow and dump it straight into the pan or drill a hole adjacent to the feed line and dump it next to the distributor drive. This would accomplish the exact same thing and slow down oil at #4 as well as cool the oil.
Duane
Well-Known Member
Once again I have say you are forgetting about the plug that is also added at the front of the galley. This also plays a major part by dead ending the system. The crossover tube is used to reverse feed #1 main. So we cannot just put a line back into the pan.
You are the only one participating in this thread who agrees that you can have uneven pressures in a hydraulic system that is open and provided a sensible explanation.
Look at the schematic pic I posted earlier and you will see the plug added to the galley.
Still can't let go of velocity, huh? Ya know, I'm supposed to be on vacation with my family this week, so I'm not going to waste it here. This is it, unless this thread is still going strong next week.
I understand pressure differentials, and fluid dynamics. If I didn't, my education in race engine technology would have been a waste. You assumed that I didn't know that pressures will be different across a fluid system. Of course they will, but that doesn't mean what you're saying is correct. Take a commercial compressed air system, for example. They start of with a huge primary pipe, with a lot of volume. But, by the time it gets to the work station, it is 1/4" pipe. Why? Because over a run, pressure will drop unless the volume is increased, or the restriction is increased. It is how pressure is maintained. I used the exact same principles when plumbing my house, so the shower wouldn't be reduced to a trickle when someone turned on the kitchen faucet. An engine block is the same way. The bearing feed galleys are the smaller than the main galley. But, the cam, and cylinder head feeds are the same size as the bearing feeds, so your grooved cam reduced the pressure drastically at the main bearings. By the way, there are a lot of solid rollers still available with the oil groove, even though it's a bad idea, IMO.
You've been talking about velocity all this time, and the failure with your engine, and then, all of a sudden, velocity had nothing to do with it. Without resistance to flow, there is no pressure. It can be lower at different points throughout the system, and will be, but putting a plug at the end of a galley, and then pulling the same volume of oil out of that galley in a crossover tube, does nothing to change that low pressure area. The pressure will still drop over that run, especially with the bleeding along the way. You can argue until your blue, but it doesn't change the physics.
Your SBC example is flawed as well. The passage that feeds the mains is not the main galley. If I had a nickel for every Chevy guy who thought his small block had priority main oiling from the factory, I'd be wealthy. The main galley on a SBC is from the pump, up to the trident, that feeds three separate galleys. Two are the lifter bores, and the other feeds the CAM first, and then finally the mains. And you think that plug at the front of the block reduces the imaginary velocity? Why did someone invent rev kits, if a lifter popping out of the bore and dumping oil wasn't a bad thing? After all, the oil isn't going to flow to the low pressure area anyway.
My point about the straight shot oiling, is that Chrysler has always used it, since at least 1958, but Chevy guys tend to think it is only exclusive to them. The Scat info you posting is new marketing of a very old, but viable, design. Take a look at marketing strategies and you'll see what I mean.
There is not a trend to use external lines to oil the rocker gear, unless the heads are deisigned that way, i.e. Indy 440-1, or spray bar oiling is being used. Aside from that, the mods are internal, and not new by any stretch.
Until next week......
Duane
Well-Known Member
B3 I will say it again. I do not believe that I said my # 2&4 main bearing failure was a velocity issue. The velocity issue is an explanation for the effect of the crossover tube.
Part of my response was not addressed to you but the other recent poster who questioned why you cannot just dump a line into the pan.
He is forgetting that if you performed the crossover mod with a plug in the front as is called for there would be absolutely no oil to the front main bearing if you put the line into the pan. The line reverse feeds the front main. At least if you have performed the mod the way Larry Atherton has recommended to do it.
You are taking bits and pieces of my previous posts and assuming they are addressed to you.
I never offered an explanation for the 2&4 failure I had. I only offered that it would be one heck of a coincidence for it to not be tied to my grooved cam journals. I think the other poster has offered a possible explanation with the low pressure drop. I simply asked if everyone agrees with that explanation.
As far as I know all crankshafts have always been drilled from the main journal over to the rod bearings. I tried to emphasize to you that the position of those holes is where the improvements have been made to address timing issues and that cross drilling is no longer recommended.
I do not even use the crossover method on my own engines.
I use the Chrysler method of tubing the block.
Your comment about the external lines on a 440-1 heads.
Are we talking about big blocks or small blocks.
I have never seen a recommendation from a Chrysler engineer put in a publication to external oil the rockers until the stroker small block book came out. But I will not say it has not been done.
As I said at the beginning I am not an expert and I have not seen everything.
Rather than continue to take my posts out of context perhaps you can offer your own explanation or how about tell us how you perform your own version of the crossover line. Make a contribution.
If you would like to read a very good thread on oiling small blocks
Do a search on Mopar chat for oiling mods by a guy named Charles
Sanborn. Here is an excerpt. It is one of the best oil mod threads I have seen and I have implemented many of his mods.
Duane
Well-Known Member
One other thing B3 please note that in the excerpt that I posted please note that Sanborn claims in the paragraph that feeding to much oil to the rockers through #2&4 cam bearing causes main bearing failure and rod bearing failure. There is no mention of velocity.
T56MaxTorq
Well-Known Member
I think we've gotten a little off course. Duane, I believe your 2&4 failure was from little things that added up to the failure. Your full groove cam without a restriction in the rocker pedestal played a part. I'm not sure about the rest of your combo like the pump, oil type, bearing clearances, etc.
Now, the oil tube mod and plug has one purpose, to take pre#4 and dump it into the other galley. Some say, as in the guitar jones oil mod write-up, that this slows down the velocity of the oil flowing by the main 4,3,2,1 ports. This will allow the oil to take the 90* turn towards the mains easier. The entire oil galley will now dead-end at #1 and the oil pressure will allow oil flow out the leakage areas in the crank/rod. The more oil leakage you have that is connected to anything that feeds the crank will drop the pressure at the crank. Full time, unrestricted oil to the head is a bigger leak compared to the crank leakage. this induces a greater pressure drop for the crank oil supply at #4,2. Not to mention, the lower pressure that the full time head oiling creates, will allow the oil to flow to the lowest pressure area, the head. This seems to be a problem when you want to rev higher and higher. Even tho you did the tube mod, the head oiling screwed you over, IMO. A restricted head would lower the pressure drop seen at the crank/head oil port intersection. That, and/or make the crank/rod bearing clearances larger. This will allow more flow past them, in turn changing the pressure drop at the head/crank intersection in your favor.
What I was pondering about using an oil cooler had nothing to do with using the tube mod/plug at all. My theory was that if the sole problem is the velocity of the oil flowing past 4,3,2,1 is great enough that it is difficult to make the 90* turn, why not slow down this velocity by dropping the pressure/flow by running a line to an oil cooler coming from the oil pressure sending unit connection. Dump this line into the pan. No tube, no plug. On second thought, the plug creating the dead end at #1 is equally important (if not more important than the tube) to this mod because the oil flow becomes much slower since it doesn't have to feed the other lifter bank at #1. The tube simply helps slow down the oil by feeding the other lifter bank before #4 as well as provide lube since its passage is now blocked by the plug in 1.
Now, the oil tube mod and plug has one purpose, to take pre#4 and dump it into the other galley. Some say, as in the guitar jones oil mod write-up, that this slows down the velocity of the oil flowing by the main 4,3,2,1 ports. This will allow the oil to take the 90* turn towards the mains easier. The entire oil galley will now dead-end at #1 and the oil pressure will allow oil flow out the leakage areas in the crank/rod. The more oil leakage you have that is connected to anything that feeds the crank will drop the pressure at the crank. Full time, unrestricted oil to the head is a bigger leak compared to the crank leakage. this induces a greater pressure drop for the crank oil supply at #4,2. Not to mention, the lower pressure that the full time head oiling creates, will allow the oil to flow to the lowest pressure area, the head. This seems to be a problem when you want to rev higher and higher. Even tho you did the tube mod, the head oiling screwed you over, IMO. A restricted head would lower the pressure drop seen at the crank/head oil port intersection. That, and/or make the crank/rod bearing clearances larger. This will allow more flow past them, in turn changing the pressure drop at the head/crank intersection in your favor.
What I was pondering about using an oil cooler had nothing to do with using the tube mod/plug at all. My theory was that if the sole problem is the velocity of the oil flowing past 4,3,2,1 is great enough that it is difficult to make the 90* turn, why not slow down this velocity by dropping the pressure/flow by running a line to an oil cooler coming from the oil pressure sending unit connection. Dump this line into the pan. No tube, no plug. On second thought, the plug creating the dead end at #1 is equally important (if not more important than the tube) to this mod because the oil flow becomes much slower since it doesn't have to feed the other lifter bank at #1. The tube simply helps slow down the oil by feeding the other lifter bank before #4 as well as provide lube since its passage is now blocked by the plug in 1.
Duane
Well-Known Member
T56. Yes I agree we have gotten off course.
It occurred to me that we may be confusing each other with some of out terminology. From now on when I say the words tube mod, I am referring to the mod where you ream out the drivers side oil galley and install copper tubes. I call this the Chrysler method.
Instead of saying just tube I will now call it the cross over line.
When I say mains I mean the main bearings not main oil galley. Lol
Having cleared that up yes T56 I totally accept your explanation.
As I was trying to explain to B3, I have never personally used the cross over line on any of my engines including the one that had the failure. That block had the "Copper tube mod" in it along with the drilled passages to the main bearings.Hv pump. You are correct that there were no restrictors at the rocker gear feed.
I am only talking about the cross over line mod for the sake of discussing it validity. I did not ever say that velocity caused the failure because my block was already modified to address that issue.
When I posted to you about putting a line into the pan I was assuming you were referring to the cross over line mod being done,
I assumed you had forgotten that the cross over line reverse feeds the #1 main bearing.
Regarding your proposed method at the sending unit, what size line would you propose. I would be worried about reducing the total system pressure to unacceptable amounts.
B3 apparently is either not convinced that there is a velocity problem with this engine,or is not convinced of the crossover lines effectiveness.
I do not have his educational background and I believe his dilemma
Is that the recommended cross over line method does not match what he has been taught.
I do not think I am the one that could provide that scientific explanation.
But this crossover line modification has been around for like 40 years. It is not new and many racers swear by it.
If we are to only go by our physics of pressures always moving to a low pressure area, then there should not even be a problem with the oil making the turns to the mains. That is probably why there are so many non believers. Incidentally I have the original Larry Atherton book here and it says that only #4&3 main bearings are affected. It also claims that the angle the fittings enter the block are critical to how much oil is diverted to the drivers side but does not tell you what the angles are.
B3 claims that using the crossover line would reduce the pressure
At the main bearings. That sounds like what your are proposing.
Maybe that's how it works. Reduce the pressure to reduce the velocity. I do not know.
Very good post by you though.
." Incidentally I have the original Larry Atherton book here and it says that only #4&3 main bearings are affected. It also claims that the angle the fittings enter the block are critical to how much oil is diverted to the drivers side but does not tell you what the angles are."
Only #3&4 are affected because #1 is now plugged and fed by tbe crossover. and that makes #2 the end of the passage with all the oil it can handle. IMHO
Only #3&4 are affected because #1 is now plugged and fed by tbe crossover. and that makes #2 the end of the passage with all the oil it can handle. IMHO
Last edited:
yellow rose
Overnight Sensation
I'll say it again. I don't care how fast the oil is going. It will make the turn. I know a guy who was paid big $$$$$$ in 1969 to try and fix the oiling issues Chrysler was having. The factory gave him 8 or 9 blocks, I can't remember how many heads and MONEY. I was having issues with my junk and the topic came up at lunch one day.
He said the thought from the Chrysler was oil velocity. They screwed with it for months. The only thing they learned was it has zero to do with oil velocity. And the crossover tube was a waste of time.
Duane, I have no issue with you bringing in other brands. As you said, I did it, with good reason. What set me off was moving away from the era we are discussing. What they are doing in 2017 has ZERO to do with what they were doing when they designed this stuff.
No matter how much you want to deny it, correct oil timing is ~70 degrees ATDC. Done and settled. If the factory moved the oil feed holes in later stuff, it is purely from a cost of manufacturing point of view. Had nothing to do with engineering. Just like a front drive oil pump. It isn't better. It's cheaper.
As for cross drilled cranks...you need to slow down and READ what I WROTE and not make up what you think I said. I NEVER have said, nor have I ever been an advocate for cross drilling a crank. If and that's a big IF the oil timing is correct, there is never a need to cross drill the crank. Ever.
However, if the oil timing is off, and you can't move the feed hole in the crank then you have no choice but to feed the oil in from the bottom and cross drill the crank, so the oil feed hole in the crank is lined up with the feed hole in the crank at ~70 degrees past TDC. That's why you cross drill it. So the oil holes line up at the correct time.
You can feed the oil anywhere you want. Noon. Six. Nine. Three. Eleven. Doesn't matter. As long as the oil feed hole in the crank lines up at the correct time. You can argue that all you want, but you'll still be wrong. It's settled engineering for high speed engine oiling. Yes, you can make it so you have the oil going to the mains first. That's how it SHOULD be, but many, many miles and passes have been made in chevrolets without priority main oiling.
In fact, I know for a fact, the NHRA BB/A national record holder in about 2004-2005 was spinning a bit over 10k, with a blown gas deal and he didn't have priority main oiling. I know. I machined the block and did some of the port work on the heads and the first valve job he set the record with. I also was able to look at his data after the runs. He was shifting at 10,200 and crossed at just over 10,600. As he kept lowering the record, the RPM kept going up. He last record holder was based on a Brad Anderson block.
That was a 2900 pound car and no more than 310 inches.
So you can argue all you want for oil velocity, where the pump is mounted, pulling oil off at the cam bearings, and anything else you can think of, but it all comes down to oil timing.
If you aren't turning over 7500, oil timing isn't as big as issue as it is at 8000 and above.
When I get a minute, I will go out and make a video that hopefully explains it better.
Oil timing is all that matters. If that is correct, everything else is superfluous.
He said the thought from the Chrysler was oil velocity. They screwed with it for months. The only thing they learned was it has zero to do with oil velocity. And the crossover tube was a waste of time.
Duane, I have no issue with you bringing in other brands. As you said, I did it, with good reason. What set me off was moving away from the era we are discussing. What they are doing in 2017 has ZERO to do with what they were doing when they designed this stuff.
No matter how much you want to deny it, correct oil timing is ~70 degrees ATDC. Done and settled. If the factory moved the oil feed holes in later stuff, it is purely from a cost of manufacturing point of view. Had nothing to do with engineering. Just like a front drive oil pump. It isn't better. It's cheaper.
As for cross drilled cranks...you need to slow down and READ what I WROTE and not make up what you think I said. I NEVER have said, nor have I ever been an advocate for cross drilling a crank. If and that's a big IF the oil timing is correct, there is never a need to cross drill the crank. Ever.
However, if the oil timing is off, and you can't move the feed hole in the crank then you have no choice but to feed the oil in from the bottom and cross drill the crank, so the oil feed hole in the crank is lined up with the feed hole in the crank at ~70 degrees past TDC. That's why you cross drill it. So the oil holes line up at the correct time.
You can feed the oil anywhere you want. Noon. Six. Nine. Three. Eleven. Doesn't matter. As long as the oil feed hole in the crank lines up at the correct time. You can argue that all you want, but you'll still be wrong. It's settled engineering for high speed engine oiling. Yes, you can make it so you have the oil going to the mains first. That's how it SHOULD be, but many, many miles and passes have been made in chevrolets without priority main oiling.
In fact, I know for a fact, the NHRA BB/A national record holder in about 2004-2005 was spinning a bit over 10k, with a blown gas deal and he didn't have priority main oiling. I know. I machined the block and did some of the port work on the heads and the first valve job he set the record with. I also was able to look at his data after the runs. He was shifting at 10,200 and crossed at just over 10,600. As he kept lowering the record, the RPM kept going up. He last record holder was based on a Brad Anderson block.
That was a 2900 pound car and no more than 310 inches.
So you can argue all you want for oil velocity, where the pump is mounted, pulling oil off at the cam bearings, and anything else you can think of, but it all comes down to oil timing.
If you aren't turning over 7500, oil timing isn't as big as issue as it is at 8000 and above.
When I get a minute, I will go out and make a video that hopefully explains it better.
Oil timing is all that matters. If that is correct, everything else is superfluous.
Duane
Well-Known Member
You know I was thinking about this post today at work and I remembered an experience I had a few weeks ago.
I own 1996 Dodge Ram diesel. As many of you probably know these trucks are notorious for the top of the dash to crack and fall apart.
I bought a new dash top and installed it a few weeks ago.
The biggest challenge with this job is to remove and reinstall the distribution "tubes" that are screwed to the top of the dash.
These tubes distribute the air flow to the defrost vents and the dash vents.
To get the top of the dash off the frame required removing many other items including the dash bezel. This bezel, when you remove it takes the air deflectors off of the air vents with it ,on the drivers side. Louvres are the things that aim the direction of the air coming out of the dash vents.
The two louvres (hope I am spelling that correct) on the passenger side did not require removal.
Once I had the new dash top bolted back on to the distribution tubes and the dash fastened back to the truck, I knew I was on home stretch with this job. Only the bezel and a few other small items to finish the job. It was very hot that day and I decided to start the engine and turn the air conditioning on to have a break and cool off.
As most vehicles do, the blower motor is located on the far right side (passenger side) of the distribution tube.
When I turned the blower motor on to its highest speed, I got a gust of wind coming out of the two drivers side vents at a force that I was not used too. What the heck was going on. Did I hook something up wrong?
I began to feel around with my hand and noticed that almost no air flow was coming out of the passenger side two vents. Almost nothing.
I continued to finish the rest of the job not knowing why the air pressures were uneven side to side.
When I put the bezel back on which includes the air deflector vents,
I turned the blower motor back on and low and behold the distribution was even again. Air was now flowing out of the two passenger vents.
Not totally even but at least you could now feel air pressure.
What does this have in common with our la small block?.
The high volume pump and the blower motor are on one end of a round tube or a round galley.
In stock form both galleys had a large leak at the extreme other end.
When that leak was present in the dash tube, the air ran almost completely by both passenger side vents. Why? Because of the large leak on the end of the tube.
When I put the drivers side air leuvres back on I introduced some resistance and slowed the velocity and forcing some of the air to flow to the two passenger side vents.
These two vents on the passenger side are closest to the blower motor and yet with no resistance on the other end farthest from the blower, little to no air flow would come out.
Does our stock la motor have a big leak at the other end of the pump?
You bet it does. The Passenger side galley is being asked to feed 6 lifter bores, before it even gets to the end. At the very end the galley is being asked to feed #1 main bearing,#1cam bearing,#1 rod bearing,and 8 more lifter bores. This creates the huge leak just like the removal of the leuvres on the dash.
The result,? The oil runs right past the two closest main bearings to the pump, just like the dash vents did.
That is why in one of my previous posts that I believe that the plug at the end of the galley is just as important as the crossover line.
With the plug in the end of the line, the oil that makes it past the crossover line only only has 3 leaks to feed instead of 11.
Rapid Robert
Well-Known Member
Yellow Rose I wanna do this & I went out & looked at a SB crank horizontle on the bench & I could not grasp it with what I had to work with right then. OK: to correct oil timing I need to block the OE feeds in the block 12 o'clock saddles (all 5?) & drill/tap/feed oil into the caps at 6 o'clock correct? (all 5?) AND do I need to cross drill the crank? & if so how/where do I drill? thank you!
Duane
Well-Known Member
Welcome back Yellow Rose.
I wanted to respond to your recent post and ask a few questions.
As you can probably tell I am a believer in the velocity issue and can appreciate that some are not.( Mostly race engine builders)
Firstly to clear up a few things.
I fully understand the reason you are proposing to cross drill to the crank and the theory on how it would improve oiling to the rods.
I do not agree that it would,but I understand the theory and the reason.
If you are not normally a proponent of cross drilling ,you could have just said that in the first place. It was not my intention to start talking about newer engines. I too only brought them into the discussion to make a point. That being that even though you feel that
The older Chev engine has a better oiling system than the la engine( which it does imho) it too had it room for improvement.
Not all changes to a newer engine are for cost reduction. Many are for ease of service in case of a problem for the dealership.
We build thousands of engines per week. Reliability is the name of the game or you lose customers. When you build thousands of engines failure trends do show up.
Secondly I have never said that the older small block Chev has priority main oiling. I also never said that the galley in the centre galley in a Chev is the "main " galley. I said exactly what B3 said that that galley does not feed the lifters. I just used different wording.
I only said that it is the galley that feeds the mains. I did not say it feeds the main bearings first, just that it feeds the mains.
The small block Mopar with a few mods oils the main bearings first and functions very much like priority main oiling imho. Not the Chev.
Now if you do not mind can I ask some questions.
Can you expand on how the 70 degrees after top dead centre is arrived at. How do you get that exact number. After all we are firing the combustion mixture at approx 35 degrees before top dead centre. There is already a downward combustion force well before 70 degrees.
Second question, Do you not believe that the oil groove in the upper half of main bearings would give enough pressure to support the rod bearings even if the oil hole is not in direct alignment with the hole in the block? In other words the oil hole in the main is exposed to oil pump pressure anywhere along that groove. And with full grooved mains everywhere.
If you look at the advertisement that I posted from Scat(hard to read) what I wanted everyone to look at was not the cross drilling or straight oiling parts but the posted clock positions of the entry and exit points where they drill the rod oiling hole relative to the main bearings.
I have acknowledged in some previous posts that your oil timing issue has merit. I am aware of it. I just do not understand how you arrived at the position that you think they should be in and your method to fix it. But I agree with the issue.
Also I agree that the issue may be more of a problem on an original
Crank. I posted that only aftermarket cranks probably would have these newer refined
oil hole positions.
It was not my intention to upset you or feud with you.
Just exchanging views here nothing more.
yellow rose
Overnight Sensation
I need to find a Chevy block and crank so I can lay the Chevy and the Chrysler side by each and do a video. Then you can get a visual on what you need to do and why.
Rapid Robert
Well-Known Member
Looking forward to it, appreciated!
yellow rose
Overnight Sensation
To answer Duanes post:
I should have pointed out I don't normally like cross drilling a crank. There is usually never a need for it. We are discussing oil timing so the cross drilling is a function of that. In fact, with factory oil timing, cross drilling a crank for high speed use can actually pull oil from the rods. Not good and counter productive. There is also more that one way to cross drill a crank, and the system that has the cross drill intersect at the feed hole is far better than a cross drill that intersects in the middle of the feed hole. That is very bad, as the centrifugal forces pull oil back from the rods. All this is just for information purposes and I never suggest cross drilling ANYTHING unless you have a specific reason to do it. So, my bad for not adding more information about cross drilling.
As for the 70 degrees past TDC that's a fairly involved story. My dad had a very close friend who was an engineering whiz. He worked on oil refining plants and nuclear power plants. He went all over the world to do the engineering on stuff like that. His specialty was hydraulics. He also straightened me out on mechanical fuel injection. That's another story.
Anyway, I spent all of 1983 building a Tunnel Rammed 14:1 340. I had pcar heads so I knew it would be tough to make power at 8000. Luckily, I had found an over the counter T/A block with 4 bolt caps and an 8 bolt crank and Carillo rods. I spent an assload of 1983 dollars to get it done. I had a Cam Dynamics roller with Engle lifters. At that time, there weren't any dynos close so it went in the car. Larry (the engineer) happened to be in town and went to the track with us. I spent the day sneaking up on it. I started shifting at 7000 and worked my way up. The last pass was going to be shifted at 8200. At the top of second, it unloaded the 3&4 rods right out of the block. Luckily, I saved the block and crank, but lost 2 rods, the cam and several valves.
That's when Larry told me I would always fight Rod bearing issues if I didn't fix the oil timing issue. That was the first I'd heard of it.
I heard through scuttle butt a local guy I'd never met was selling a complete W-2 engine, with T/A block, 8 bolt crank and Carillo rods. I thought it was BS but I went to look at it. It was exactly what is was supposed to be. The difference was he had corrected the oil timing. I almost fell over. It was about six months before I'd heard of oil timing and here was guy selling out who had the same issue I had.
We pulled the pan off and there it was. I had spent the better part of 6 months trying to figure out how to fix the oil timing issue and here was a guy who had DONE it. He had paid an engineer to figure it out.
As I've said, his was a simple, effective fix. It was just that not all the oil was filtered all the time. The oil was filtered but the oil going to the mains was before the filter.
I took about 30 pictures, had them developed (yes, I'm that old) and sent them to Larry. He said it works, just make sure the crank is cross drilled. So I drove over with a check and pulled the cap. Sure enough, it was cross drilled.
I beat the crap out of that thing for years. In 1998 I bought two X blocks and set the T/A block aside. I eventually sold the block to a guy doing a clone T/A car. I still have the crank and W-2 heads from that guy.
I eventually changed the system so all the oil was filtered all the time, but that was the only change I ever made.
Before I started doing all my own machine work, I had 2 different machinists who didn't understand how oil timing works talk me into small changes. I paid a big price for those changes. Just like lock work, 3&4 rods would come out. By then, I was running aluminum rods. I then put it back just like it was and the carnage stopped. So I've proven it works.
Larry died in 1992. In 1990 he sent me a 1950 engineering book that explained how oil timing works, and how they came up with the about 70 degrees after TDC was when full pressure and flow needed to be at the rods. I spent an hour last night looking for the book. I have over 1100 books in my library and I didn't see it. I may have loaned it to my brother, or a friend in Arizona. If it went to Arizona, I'll never get it back because he died in 2015. I'm sure if you look around you can find an automotive engineering book that will explain it.
I do know that David Reher and David Nickens know it. I was talking to DR in 1989 in Seattle about it. In 1998 I had the opportunity to mee Davis Nickens at PIR when he was there with his PS truck racing Bart Price. I also me Larry Morgan and knew he was going to a Dodge before almost anyone else.
I haven't talked to DN since about 2005 but we had some long phone conversations about PST, how Dodge didn't want to budge on body shape, even though it was killing the Dodges. He also agreed with the 70 degree oil timing. So I know it's known out there.
That's the short version.
As for bearing grooves...their purpose is to get the flow started out to the rods BEFORE the need is there. The groove really only needs to go past the main feed hole about 30 degrees. But it it's easier to cut the groove around the entire bearing. The reason no one uses full groove bearings on chevies is the oil timing is correct.
A full groove bearing let's oil go to the rods all the time. If you are picking the pepper out of the fly poop, this is a bad thing. Oil going to the rods full time increase oil use and we all know the less oil flow you need, the smaller the pump you can use and still feed the system. And, as RPM goes up, the leaks become greater. All that oil gets wrapped in the crank. So that means power getting eaten up. That's why most guys don't ever use full groove bearings. If the timing is correct you just don't need them. Unless it's a Chrysler and you are trying to fix the oil timing. I always use full groove bearings on Chryslers. Always. I'll give up the power and windage looks to keep the rods in the block.
How they came up with the 70 degree number was that is ABOUT where max load on the rod bearing is. It depends a bit on Rod to stroke ratio and a couple other things, but max load on the Rod bearings is always about 70 degrees past TDC. That's why you need full pressure and flow at that time. Chrysler sends the oil to the rods too soon. So by the time max load occurs, the full pressure and flow oil is past, and all you are getting is the oil that goes around the groove. And it's not full pressure or full flow. It doesn't take long for the rods to unhook from the crank. At 8000 plus RPM, the damage is catastrophic.
The biggest thing with Chryslers is full groove mains, stop the oil leaks at the lifter bores, use a high volume pump and the biggest pickup tube you can fabricate or buy. That will get you safely to 7500 or so. After that, you are asking to kill parts and you need to correct the oil timing.
I can safely say I've never seen a GM block without the correct oil timing. Ever. The early pcar blocks didn't have priority main oiling apbut the timing was correct. Certainly, the oil took a most circuitous route, and getting oil to the mains before the lifters makes the best sense, it only means you can use a smaller pump and have less windage loss. All good things if your trying to run down Jason Line for the money, but if you are just trying to make power at high RPM and keep the rods where they belong, oil timing is what makes them live.
I should have pointed out I don't normally like cross drilling a crank. There is usually never a need for it. We are discussing oil timing so the cross drilling is a function of that. In fact, with factory oil timing, cross drilling a crank for high speed use can actually pull oil from the rods. Not good and counter productive. There is also more that one way to cross drill a crank, and the system that has the cross drill intersect at the feed hole is far better than a cross drill that intersects in the middle of the feed hole. That is very bad, as the centrifugal forces pull oil back from the rods. All this is just for information purposes and I never suggest cross drilling ANYTHING unless you have a specific reason to do it. So, my bad for not adding more information about cross drilling.
As for the 70 degrees past TDC that's a fairly involved story. My dad had a very close friend who was an engineering whiz. He worked on oil refining plants and nuclear power plants. He went all over the world to do the engineering on stuff like that. His specialty was hydraulics. He also straightened me out on mechanical fuel injection. That's another story.
Anyway, I spent all of 1983 building a Tunnel Rammed 14:1 340. I had pcar heads so I knew it would be tough to make power at 8000. Luckily, I had found an over the counter T/A block with 4 bolt caps and an 8 bolt crank and Carillo rods. I spent an assload of 1983 dollars to get it done. I had a Cam Dynamics roller with Engle lifters. At that time, there weren't any dynos close so it went in the car. Larry (the engineer) happened to be in town and went to the track with us. I spent the day sneaking up on it. I started shifting at 7000 and worked my way up. The last pass was going to be shifted at 8200. At the top of second, it unloaded the 3&4 rods right out of the block. Luckily, I saved the block and crank, but lost 2 rods, the cam and several valves.
That's when Larry told me I would always fight Rod bearing issues if I didn't fix the oil timing issue. That was the first I'd heard of it.
I heard through scuttle butt a local guy I'd never met was selling a complete W-2 engine, with T/A block, 8 bolt crank and Carillo rods. I thought it was BS but I went to look at it. It was exactly what is was supposed to be. The difference was he had corrected the oil timing. I almost fell over. It was about six months before I'd heard of oil timing and here was guy selling out who had the same issue I had.
We pulled the pan off and there it was. I had spent the better part of 6 months trying to figure out how to fix the oil timing issue and here was a guy who had DONE it. He had paid an engineer to figure it out.
As I've said, his was a simple, effective fix. It was just that not all the oil was filtered all the time. The oil was filtered but the oil going to the mains was before the filter.
I took about 30 pictures, had them developed (yes, I'm that old) and sent them to Larry. He said it works, just make sure the crank is cross drilled. So I drove over with a check and pulled the cap. Sure enough, it was cross drilled.
I beat the crap out of that thing for years. In 1998 I bought two X blocks and set the T/A block aside. I eventually sold the block to a guy doing a clone T/A car. I still have the crank and W-2 heads from that guy.
I eventually changed the system so all the oil was filtered all the time, but that was the only change I ever made.
Before I started doing all my own machine work, I had 2 different machinists who didn't understand how oil timing works talk me into small changes. I paid a big price for those changes. Just like lock work, 3&4 rods would come out. By then, I was running aluminum rods. I then put it back just like it was and the carnage stopped. So I've proven it works.
Larry died in 1992. In 1990 he sent me a 1950 engineering book that explained how oil timing works, and how they came up with the about 70 degrees after TDC was when full pressure and flow needed to be at the rods. I spent an hour last night looking for the book. I have over 1100 books in my library and I didn't see it. I may have loaned it to my brother, or a friend in Arizona. If it went to Arizona, I'll never get it back because he died in 2015. I'm sure if you look around you can find an automotive engineering book that will explain it.
I do know that David Reher and David Nickens know it. I was talking to DR in 1989 in Seattle about it. In 1998 I had the opportunity to mee Davis Nickens at PIR when he was there with his PS truck racing Bart Price. I also me Larry Morgan and knew he was going to a Dodge before almost anyone else.
I haven't talked to DN since about 2005 but we had some long phone conversations about PST, how Dodge didn't want to budge on body shape, even though it was killing the Dodges. He also agreed with the 70 degree oil timing. So I know it's known out there.
That's the short version.
As for bearing grooves...their purpose is to get the flow started out to the rods BEFORE the need is there. The groove really only needs to go past the main feed hole about 30 degrees. But it it's easier to cut the groove around the entire bearing. The reason no one uses full groove bearings on chevies is the oil timing is correct.
A full groove bearing let's oil go to the rods all the time. If you are picking the pepper out of the fly poop, this is a bad thing. Oil going to the rods full time increase oil use and we all know the less oil flow you need, the smaller the pump you can use and still feed the system. And, as RPM goes up, the leaks become greater. All that oil gets wrapped in the crank. So that means power getting eaten up. That's why most guys don't ever use full groove bearings. If the timing is correct you just don't need them. Unless it's a Chrysler and you are trying to fix the oil timing. I always use full groove bearings on Chryslers. Always. I'll give up the power and windage looks to keep the rods in the block.
How they came up with the 70 degree number was that is ABOUT where max load on the rod bearing is. It depends a bit on Rod to stroke ratio and a couple other things, but max load on the Rod bearings is always about 70 degrees past TDC. That's why you need full pressure and flow at that time. Chrysler sends the oil to the rods too soon. So by the time max load occurs, the full pressure and flow oil is past, and all you are getting is the oil that goes around the groove. And it's not full pressure or full flow. It doesn't take long for the rods to unhook from the crank. At 8000 plus RPM, the damage is catastrophic.
The biggest thing with Chryslers is full groove mains, stop the oil leaks at the lifter bores, use a high volume pump and the biggest pickup tube you can fabricate or buy. That will get you safely to 7500 or so. After that, you are asking to kill parts and you need to correct the oil timing.
I can safely say I've never seen a GM block without the correct oil timing. Ever. The early pcar blocks didn't have priority main oiling apbut the timing was correct. Certainly, the oil took a most circuitous route, and getting oil to the mains before the lifters makes the best sense, it only means you can use a smaller pump and have less windage loss. All good things if your trying to run down Jason Line for the money, but if you are just trying to make power at high RPM and keep the rods where they belong, oil timing is what makes them live.
T56MaxTorq
Well-Known Member
YR, thank you for your input.
Would a simpler solution be to use flat bearings and just machine your own deep groove to a certain degree to correct the timing? Is this the (failed) change you were talked into by your machinist buddies? I understand you also emphasized that the main feed hole and the crank hole need to line up at the critical 70 degrees for the most pressure possible. I'm sure you've brainstormed ideas on how to not drill the crank.
I do believe that the velocity issue is still true to the oil crossover tube mod. Like a stock block has almost has a venturri type effect upon #4/2. More so if you have unrestricted, full time head oiling. Whether or not it makes a difference in the big picture, I don't know.
Would a simpler solution be to use flat bearings and just machine your own deep groove to a certain degree to correct the timing? Is this the (failed) change you were talked into by your machinist buddies? I understand you also emphasized that the main feed hole and the crank hole need to line up at the critical 70 degrees for the most pressure possible. I'm sure you've brainstormed ideas on how to not drill the crank.
I do believe that the velocity issue is still true to the oil crossover tube mod. Like a stock block has almost has a venturri type effect upon #4/2. More so if you have unrestricted, full time head oiling. Whether or not it makes a difference in the big picture, I don't know.
I think the reason that some engine builders bush the lifter bores and change to push rod oiling , is to eliminate using the crossover tube.
Duane
Well-Known Member
A most excellent and informative post. I will be archiving this one.
Thanks for that lengthy and very technical explanation.
These are the kinds of post that make this forum worthwhile when we can learn something.
I have to ask though did the wife get lucky when you saw that gear drive on the Hemi.? Lol
Duane
Well-Known Member
Some other ideas for you to consider. These are pics of a mod being performed on an older Chev small block. I believe this mod is lifted from the new ls motor and is similar to how we do it at work.
I think the pics and advantages to help rod bearing oiling are self explanatory.
Duane
Well-Known Member
-
