The bolt centers itself at the head with a taper in the shank.
Pushrod oiling - do I need it?
- Thread starter rmchrgr
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Newbomb Turk
Well-Known Member
That doesn’t sound right. I thought the dowel pins located the head and gasket. If that’s the case, the bolts or studs location will be based on where the dowel pins are actually located compared to the blueprint and where the bolt holes were drilled in the head and where the threads locate the fastener in the block. It would seem the bolt is just where it is.
MOPAROFFICIAL
Oogliboogli
To that I will just respond with cut all the flashing off of the head in the returns and you can order the push rod with it smaller diameter oil feed hole and honestly it's not really going to starve the bottom end especially if we're racing or doing some performance **** cuz we're probably going to have a few extra quarts in the pan , you know what I mean?
I'll just share my experience with you I skipped on the pushrod oiling and all the top of cup ends on my push rods had turned blue. Induction hard and shafts, Comp Cams rockers, 225 seat 500 open just under 600 lift. I'm all about having a little oil there after that experience.
Clean up the flashing in the head if it has some, if not ....disregard that.
Clean the flashing at the valley returns.
My 340 has head studs
But I used bolts in the 2 oil passages.
Been working fine for about two years
Daily Driven.
My 2c
But I used bolts in the 2 oil passages.
Been working fine for about two years
Daily Driven.
My 2c
rmchrgr
Skate And Destroy
Several years ago before the block was machined, I spent a lot of time de burring it inside and out and made sure all the openings in the lifter valley were smoothed. The lifter valley is also painted with Glyptal which supposedly promotes drain back by keeping the oil from absorbing into the porous surface of the cast iron. There really isn't much casting flash on the aluminum heads I have.
Not sure if you had a high volume pump when you had things burn up on you but I do. At one point I bought one from Precision with moly coated gears but I inadvertently cracked it trying to install it over a stud that was too long. I got regular HV72, swapped in the coated gears and enlarged the entry by copying what Precision did. Works fine with the standard 3/8 pickup. Oil pan is a Kevko M301 with a built in crank scraper. Holds 5 quarts in the pan itself and accommodates 6 quarts in the system.
I mentioned this already but the Hughes rocker arms have an oiling hole for the adjuster tip. It's not for pushrod oiling but it does squirt whatever oil is available at that orifice out the back of the rocker arm toward the adjuster ball and pushrod cup. If there was some amount of additional, pressurized oil coming up through the pushrod to the same point that is already being lubed by the hole in the rocker, it stands to reason there would be excess oil.
With pushrod oiling, all 16 rods are always filled so there's a couple cubic inches of oil in them at all times. Compared to bearing surfaces, the areas of contact between the adjuster ball and pushrod cup are relatively small most of it becomes waste. There is no direct path for the oil to get back to the crank case so it's just sitting there doing nothing. The volume of that excess oil also ends up being more than what's in the pushrods since the rate of drain back is slower than pressurized oil being forced though a small orifice.
It's not only about getting oil to a spot but you also have to consider what happens with any extra oil that has to go back to the crankcase. Pick your poison.
mopowers
Well-Known Member
How much oil can the top of an engine actually hold at any given time?
Maybe this will help you understand, Look at the bolts pictured . The top of the bolt keeps the shank centered in the hole which allows space to be spread evenly around the bolt for the oil to travel. This insures the bolt shank not to move against the smaller drilled oil feed hole in the top of the head when torquing it.
Common ARP Studs do not have this under cut in the shank. They are the same exact diameter as the hole which leaves no room for oil to travel. Can you drill the head? Yes, Go ahead be my guest. And who is to say the stud stays in the center at the top of the hole after torqued with no taper to keep it centered.
You all can drill the head hole larger. We'll keep doing what we do for over 30 years with no issues. Using the proper bolt or Modifying the 2 studs.
And as far as the Call to ARP. I say Bullshit! My son talks to them weekly he is a dealer for them and places orders every week. We discussed this with them at great detail on how much could be removed without compromising the tensile strength torque value recommended for this application . It took over #125 lbs without any failure far exceeding the torque needed. They are also used over when the engines are refreshed for the new race season and still torque just fine.
When doing this mod don't grind it in . It must be cut uniform and no uneven edges rough edges.
Last picture they do make and sell under cut studs. There is one pictured with standard studs. Very expensive. 4 times the amount then standard thread rolled heat treated studs.
The $100 a set is what we are paying for the stud kit. To have the 2 studs modified it is around $25 a pair for engines built here.
Newbomb Turk
Well-Known Member
I posted exactly what Steve at ARP said. Anyone is free to call them and see what they get for an answer.
There is a big difference between an undercut stud and machining a stress rider in the stud.
What you claim is centering the bolt (if it does what you say) is actually bending the bolt if there is any misalignment between the bolt and the hole. Studs don’t generally have that step.
MopaR&D
Nerd Member
Not very much, also once the oil starts flowing on the drain back side it doesn't really matter. Whatever the heads and lifter valley can hold just becomes a reservoir of sorts and the faster the oil gets pumped up there the faster it flows back.
It’s surprising what a very small orfice can flow. Bret had a video on Facebook of how much one would flow under way less than 50-70 pounds of pressure. I don’t restrict my oil but I do everything humanly possible to keep oil out of spots I want limited oil and get it back to the oil pan. Im
Betting I haven’t bought a head or main stud kit in well over 20 years for my builds. But I’m also not building engines for customers. I have two huge plastic totes of 7/16 and 1/2 inch main studs and head bolt studs. I grab what I need and go with it. Now I will buy new washers and nuts occasionally. I refuse to use any type of air tools or battery tools on my engines or transmissions. ( except on my balancer bolt) everything else is done by hand.
Betting I haven’t bought a head or main stud kit in well over 20 years for my builds. But I’m also not building engines for customers. I have two huge plastic totes of 7/16 and 1/2 inch main studs and head bolt studs. I grab what I need and go with it. Now I will buy new washers and nuts occasionally. I refuse to use any type of air tools or battery tools on my engines or transmissions. ( except on my balancer bolt) everything else is done by hand.
MOPAROFFICIAL
Oogliboogli
Consider the crank case pressure and mainly windage .. and its effect on oil return... oil is airborne at rpm coming off of the internal components. The pushrods maybe hold about a tea spoon each. It's not much. More oil is coming off the cam/lifters than the push rods at rpm...consider uaing a valley baffle.
Run it, inspect it.. then change what's necessary if anything at all.
rmchrgr
Skate And Destroy
This is an exxageration but trying to oil the adjuster tips through the pushrods is sort of like filling up a Dixie cup with a garden hose. Of course some water will go in the cup but the majority of it won't and will invariably just splash on the ground. Even if you reduce the volume coming out of the hose, the cup will still fill up pretty fast. Once the cup is full, everything else you attempt to put in it just becomes excess. Now imagine 16 hoses trying to fill 16 Dixie cups. OTOH, there would be little point in adding extra volume by a slow drip if another source (shaft oiling) was maintaining an acceptable volume for the purpose at hand.
When you pop a valve cover or the intake there is always some amount of oil sitting in the head or at the bottom of the lifter valley. That oil isn't in the crank case so clearly drain back is not instant nor is it 100% efficient. Just saying that if you're pushrod oiling and shaft oiling at the same time and the amounts of oil sitting in those areas increases beyond what's normally acceptable you might have a problem elsewhere.
I still maintain that the rate of drain back has to be lower than the rate of the pressure-fed oil being forced through an orifice. To me, that means the excess volume increases faster than what's being pumped out through the galleries (or pushrods) which effectively decreases the available volume of pressurized oil to the galleries by that same amount. It's probably not much but it is something.
The whole question is whether the stock system is adequate for whatever level of abuse you're carrying out. With a HV oil pump, one would hope it's sufficient. Like you said, only way to find out is to run it and inspect things. Not sure if a specific pressure for a given rpm becomes a warning sign. If you're tunring 7,000 rpm on a regular basis and only seeing 60 psi maybe you'd want to check things a little more often or it might even be too late already.
Honestly, I don't know if any of this is exactly right but I do think there is some truth to it since pushrod oiling generally requires reducing or blocking off the oil going to the rocker stand in order to prevent excess oil from going to the head. Take that for what it's worth I guess.
Last, reason says that if pushrod oiling was truly necessary for a certain level of perfromance above stock, manufacturers like ARP or Hughes would design their parts to facilitate it. From what I can tell, that's never been the case for your garden variety street/strip situation so it's really not worth fussing over something that is most likely not needed.
rmchrgr
Skate And Destroy
For my own edification and to clear up any confusion, here are some pics comparing a stock head bolt to an ARP head stud. OMM used the word 'taper' to describe this situation but I would say it's more of a step. Normally I'd think of a taper being like the conical area underneath the wider part. Either way, you get the idea.
Here's the stock bolt. Note the step in the shank under the head. I admit I had never noticed that before. I always knew the one bolt was a different length but never noticed the step or what it might be there for.
Top of the shank diameter measurement.
Diamter decreases .050" below the step.
ARP head stud shank diameter. There is no step as with the OE bolt.
Diamater of the bolt hole in a stock, '70's cast iron cylinder head.
Diamater of the same bolt hole on an Edelbrock aluminum head.
Even though the step is clear as day now, I'm still not understanding the point of it and it's affect on oiling. There are two holes off the rocker stand oil passageway on the intake side of the hole; one is above the other by about 3/8" or so. In my mind, pressurized oil comes out the bottom hole, fills the area around the bottom of the bolt shank, goes back into the top hole and then out the rocker stand orifice. Again, my best guess for doing this is that the oil flowing around that bolt shank creates a dampneing or swiriling affect on the pressure feed so it does not just spray everywhere.
Regardless, since the bolt holes in both the stock and aftermakret heads look to be about .0025" larger than the ARP stud shank, some amount of oil is definitely flowing around the stud shank. Machining a recess in the shank will obviously add more volume but again, it does not seem necessary since there is no step in the stud like with the bolt. Without that step down in diamater, the airspace volume around the stud shank would probably end up being about the same as with the stock bolt. There's no need for the step anyway because there is no bolt head.
So yeah, I'm just gonna stay with the studs as-is. Never been a problem before and now that I verified things with hard numbers, I really can't see how a straight-shank stud could create any sort of restriction since the inner diamater of that bolt hole provides enough volume for that little bit of oil to flow into.
Here's the stock bolt. Note the step in the shank under the head. I admit I had never noticed that before. I always knew the one bolt was a different length but never noticed the step or what it might be there for.
Top of the shank diameter measurement.
Diamter decreases .050" below the step.
ARP head stud shank diameter. There is no step as with the OE bolt.
Diamater of the bolt hole in a stock, '70's cast iron cylinder head.
Diamater of the same bolt hole on an Edelbrock aluminum head.
Even though the step is clear as day now, I'm still not understanding the point of it and it's affect on oiling. There are two holes off the rocker stand oil passageway on the intake side of the hole; one is above the other by about 3/8" or so. In my mind, pressurized oil comes out the bottom hole, fills the area around the bottom of the bolt shank, goes back into the top hole and then out the rocker stand orifice. Again, my best guess for doing this is that the oil flowing around that bolt shank creates a dampneing or swiriling affect on the pressure feed so it does not just spray everywhere.
Regardless, since the bolt holes in both the stock and aftermakret heads look to be about .0025" larger than the ARP stud shank, some amount of oil is definitely flowing around the stud shank. Machining a recess in the shank will obviously add more volume but again, it does not seem necessary since there is no step in the stud like with the bolt. Without that step down in diamater, the airspace volume around the stud shank would probably end up being about the same as with the stock bolt. There's no need for the step anyway because there is no bolt head.
So yeah, I'm just gonna stay with the studs as-is. Never been a problem before and now that I verified things with hard numbers, I really can't see how a straight-shank stud could create any sort of restriction since the inner diamater of that bolt hole provides enough volume for that little bit of oil to flow into.
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Newbomb Turk
Well-Known Member
The pictures show it. Your measurements show that the shank of the bolt is .050 under nominal. So you can easily make the hole is the head a 1/16th over nominal and run it. If anyone is that concerned about oil to the rocker gear, put a groove in the cam. You’ll get full time oil to the rockers. Not always a good thing.
We have seen the bolt holes as small as .502 on some heads . But what I think was the game changer for the shop was when reinstalling the Indy heads on a race engine where the rockers were starving for oil we noticed the stud was tight against the hole in the head.
Most know when installing or removing a head with the studs in place they are tight going on and off. Also there is no insurance that when tightening that nut on that stud the the stud stays center. If you pull the torque wrench toward the one side it may stay against that side. A hole that is .502 with a stud thats .499 doesn't leave much room for error on 10 holes in the head.
14-1 compression on a alcohol engine and never did we have a cut stud that was compromised .
The Taper/step in the bolt guarantees the hole to be open. There is no step cut in the stud at all and no room for error and no way to check it once its assembled and torqued. So its either buy a tapered/stepped stud set which they do sell. Or take the chance on the oil getting to the top. We have not gulled any push rods or destroyed and needle bearings in the rockers since we have been doing this.
If your building your own engine and you can afford the possible damage from lack of oil then take the chance. Because we have seen the carnage from lack of oil to the heads from straight cut studs. We found the groove cut in the stud is the best way rather then cutting the whole stud shank to a smaller diameter. Or just use bolts. Drilling the head does not prevent the stud from the possibility of the stud covering the hole in the head. What we do works for sure and never a stud failure.
Take this info for what its worth I am only trying to inform you on what we have found to help members. If I was building a street engine I would use bolts. Very high compression engines or engines with boost need studs. High boost he will o-ring the block or heads .
rmchrgr
Skate And Destroy
OMM Thank you for the clarification. The bolt holes on the heads I am using are sufficient diameter so no need for me to do anything to the stud or hole. If it was too tight I would definitely enlarge the hole .0025” or whatever. At least I know to check for it now.
If this were a dedicated race engine I’d probably tube the lifter gallery, block the timed cam bearing feeds and install a crossover line from the #4 to the #2 feeds for full-time oiling. In that case T&D rockers would be required for pushrod oiling.
My engine is nowhere near the level of performance you’re dealing with though so I’m not concerned with the stud being a problem. 7,000 rpm would be about the max I would turn and that would only be for a few seconds anyway. Sustained rpm would be a different story but this is a street car which will see part throttle operation 90% of the time.
I also still don’t believe the step in the bolt is there for added capacity because there’s really not a whole lot of volume involved. Again, my gut tells me it’s for dampening the timed pulses from the cam journal feed. And if you switch to pushrod oiling the stud no longer matters anyway.
If this were a dedicated race engine I’d probably tube the lifter gallery, block the timed cam bearing feeds and install a crossover line from the #4 to the #2 feeds for full-time oiling. In that case T&D rockers would be required for pushrod oiling.
My engine is nowhere near the level of performance you’re dealing with though so I’m not concerned with the stud being a problem. 7,000 rpm would be about the max I would turn and that would only be for a few seconds anyway. Sustained rpm would be a different story but this is a street car which will see part throttle operation 90% of the time.
I also still don’t believe the step in the bolt is there for added capacity because there’s really not a whole lot of volume involved. Again, my gut tells me it’s for dampening the timed pulses from the cam journal feed. And if you switch to pushrod oiling the stud no longer matters anyway.
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