Missed on this combo?

[B3RE]

A couple of points here.

First, the pushrod angle changes as it goes through the lift cycle. The more lift, the more extreme the angle, so there is no magic number to plug into the trig formula. It is usually more than 11*, especially with a roller lifter.

Also, the sweep of the rocker would eat up some lift, but remember, the pushrod also sweeps, so it gets closer to the shaft centerline as it gets away from the perpendicular line at mid lift, so in theory that increases the ratio and offsets some of the losses at the valve. This is provided the rocker is properly designed, and most are not.

There is some sweep on the valve tip, but at .035" for .600"+ lift on a SBM, I'd say it's as good as it gets. It's the pushrod side that is almost impossible to correct, especially with that ball type adjuster. A roller rocker is a different animal, and the ball adjuster is a bad holdover from the stock design.

Also, the lash is not set on the pushrod side, it is on the valve side which has already accounted for the rocker ratio. You would not multiply the lash by the rocker ratio. It is as measured.

Looking at the dyno sheet, it looks like you have a bunch of reversion down low, killing the bottom end. Then the lobe separation and ICL is not letting the torque carry in the higher rpms, which is killing the horsepower.

Another observation is the improvement with only a half inch spacer. A larger spacer may have helped more, and it's likely due to airspeed being too high at the base of the carb for the air to turn and follow the roof of the intake port. It will shear off the turn there, just like the short turn in the cylinder head, if the airspeed is to high. There could also be turbulence under the carb choking off airflow as the mixture exits the throttle bores. A shear plate may help if that is the case.

JMO

 

[nm9stheham]

Hey ya didn't finish your post..... "works out to" what? Please elaborate.......

I have the B3 geometry correction kit. My rollers don't roll out or in at all. Geometry is perfect.

It ought to be finished now.

Yes, I read that you had the correction kit, but even with the B3 kits, the rollers will move with rocker motion. Think of it: the end of the rocker is swinging in an arc, and the roller axle is moving in and out as it swings up and down. The valve tip is moving in a straight line. No way there will be no motion at the roller vs valve tip. The correction just minimizes the loss of lift and the in/out motion of the roller.

This same arc motion of the tips of the rockers also causes loss of lift; such loss is almost negligible at stock lifts, but when the lifts get up into your range, it is not as small anymore. I don't have the general SBM rocker length tip-to-tip in front of me, but I'll make an estimate. I got a spreadsheet for this somewhere....

 

[nm9stheham]

Just ran some rough numbers... I guessed at the tip-to-tip rocker length as being about 2-3/4" so if that is off, then the number are off in proportion. And note that this change of lift at the rocker tips due to the rotation occurs at both ends; the vertical motion of the pushrod end at the rocker gives a bit more rotation than would be expected, and so somewhat compensates the loss of at the valve end. (For a 1:1 rocker, it would all cancel out.)

With my rough numbers, it looks like you are losing about .003" to .004" more just from and 'ideal' design at these lifts, but the ball position makes it worse as noted. So now you have lift losses roughly in the range of:
- .010" from the lash (Thanks for the correction! duh...)
- .012" from push rod angle
- > .004" from general design of the rocker

So roughly half of your loss of lift is just in these things assuming they gave you a valve lift at a given rocker ratio. I have not looked at how your cam is spec'd; if they spec just lobe lift, then you use the rocker ratio times the tappet lift minus these corrections to get to the real valve lift. Now if they advertise a specific valve lift, then it ought to be there. (I suspect that most cam mfr's just multiply the lobe loft by the rocker ratio and give that as advertised lift, but I don't know that as a fact.)

And for sure, the .030-.035 roller motion on the tip is right for the 'best you can do' correction. Again, this is just naturally from the design of the rocker.

 

[Ironmike]

A couple of points here.

First, the pushrod angle changes as it goes through the lift cycle. The more lift, the more extreme the angle, so there is no magic number to plug into the trig formula. It is usually more than 11*, especially with a roller lifter.

Also, the sweep of the rocker would eat up some lift, but remember, the pushrod also sweeps, so it gets closer to the shaft centerline as it gets away from the perpendicular line at mid lift, so in theory that increases the ratio and offsets some of the losses at the valve. This is provided the rocker is properly designed, and most are not.

There is some sweep on the valve tip, but at .035" for .600"+ lift on a SBM, I'd say it's as good as it gets. It's the pushrod side that is almost impossible to correct, especially with that ball type adjuster. A roller rocker is a different animal, and the ball adjuster is a bad holdover from the stock design.

Also, the lash is not set on the pushrod side, it is on the valve side which has already accounted for the rocker ratio. You would not multiply the lash by the rocker ratio. It is as measured.

Looking at the dyno sheet, it looks like you have a bunch of reversion down low, killing the bottom end. Then the lobe separation and ICL is not letting the torque carry in the higher rpms, which is killing the horsepower.

Another observation is the improvement with only a half inch spacer. A larger spacer may have helped more, and it's likely due to airspeed being too high at the base of the carb for the air to turn and follow the roof of the intake port. It will shear off the turn there, just like the short turn in the cylinder head, if the airspeed is to high. There could also be turbulence under the carb choking off airflow as the mixture exits the throttle bores. A shear plate may help if that is the case.

JMO

so, can retarding the cam help with the reversion? Or maybe a better cam grind? And what the heck is a shear plate, Mike?

 

[B3RE]

so, can retarding the cam help with the reversion? Or maybe a better cam grind? And what the heck is a shear plate, Mike?

Well, closing the intake valve later would actually increase intake tract reversion, and should help the top end. However, the exhaust reversion that comes with a lot of overlap dilutes the intake mixture and causes a week bottom end as well. With your combination (and I know Yellow Rose will disagree with me on this), I would have gone wider on the lobe seperation, and reduced the intake charge contamination from the overlap period. That would also equate to a later intake closing event if installed with the same amount of advance, which would help top end power, but the higher quality (less diluted) intake charge should help the bottom some as well.

A shear plate is a spacer that fits under the carburetor, and is specially machined to break up the turbulent swirls that choke off airflow exiting the throttle bores. Its seen a lot on high rpm engines that have a large plenum under the carb pad. Air likes to follow a surface, and when it can't, it tumbles which induces turbulence and reduces flow. Short answer, a very expensive carb spacer.

 

[RAMM]

Looking at the dyno sheet, it looks like you have a bunch of reversion down low, killing the bottom end. Then the lobe separation and ICL is not letting the torque carry in the higher rpms, which is killing the horsepower.

Read this ^^^^^ and read it well. Your intake manifold is directly connected to the exhaust system. IMO retarding the cam isn't going to fix the bottom end AND add power up top. Smaller , longer collectors will make a big difference in this case. Your cam does not play nice with the induction tract and exhaust tract. I bet if you ran this engine for a longer period of time you would see exhaust half way up the intake port, maybe further. J.Rob

 

[RAMM]

Well, closing the intake valve later would actually increase intake tract reversion, and should help the top end. However, the exhaust reversion that comes with a lot of overlap dilutes the intake mixture and causes a week bottom end as well. With your combination (and I know Yellow Rose will disagree with me on this), I would have gone wider on the lobe seperation, and reduced the intake charge contamination from the overlap period. That would also equate to a later intake closing event if installed with the same amount of advance, which would help top end power, but the higher quality (less diluted) intake charge should help the bottom some as well.

A shear plate is a spacer that fits under the carburetor, and is specially machined to break up the turbulent swirls that choke off airflow exiting the throttle bores. Its seen a lot on high rpm engines that have a large plenum under the carb pad. Air likes to follow a surface, and when it can't, it tumbles which induces turbulence and reduces flow. Short answer, a very expensive carb spacer.

Totally agree with the statement on LSA. A single pattern cam on a 112 LSA with a possibly slower lobe would make a big difference. Of course if the real problem is the intake port is not moving the air and going turbulent (as I have had happen and think this is the case here) then nothing will fix it. What you have here is a great opportunity to learn. I'd get the cam reground with less duration and lift on the exhaust side before going back to dyno. J.Rob

 

[B3RE]

Totally agree with the statement on LSA. A single pattern cam on a 112 LSA with a possibly slower lobe would make a big difference. Of course if the real problem is the intake port is not moving the air and going turbulent (as I have had happen and think this is the case here) then nothing will fix it. What you have here is a great opportunity to learn. I'd get the cam reground with less duration and lift on the exhaust side before going back to dyno. J.Rob

Jesse,
I agree that if the head port is going turbulent, it would be tough to fix. But, seeing the horsepower gain from only a half inch spacer makes me think the air needs a longer transition into the intake runner. After seeing 7 hp with that little spacer, I would have started stacking every spacer I could find on there, just for the data to analyze. Its probably not the whole story, but worth looking into. I had a 470 give up at 4800 rpm because of this.

And yes, a 112 LSA, although I don't think I would automatically go smaller on lift or duration. Maybe, maybe not.

 

[Ironmike]

so, I see these words,, "Of course if the real problem is the intake port is not moving the air and going turbulent"...........and wonder WHY this could be the problem. Is it heads? Intake? Cam itself? How can I tell if the head port is going turbulent?

I got 1 more shot on the dyno. One. And I have to absolutely fix this thing. I cant change heads. So everything else is a possibility.

Reversion as far as I understand is a cam issue. Hell, I'll change cams if need be, but it don't make sense. Tim at Bullet asked me every single build detail you could think of. If somebody said "change cams, all will be fine", id tear it apart tonite. and call Shane at Crower Monday.

Not sure what my plan of attack should be.

I have the exact same intake done by me the same way, on my current engine with a 640/640 lunati, 110 LSA installed at 104. Made a buttload more torque down low.

all that said, I still think I should have more lift at the valve. I'm checking my other engine when I get home. I'm betting I have somewhere around .627 (.640 minus .013 lash).

of course I might be wrong

 

[B3RE]

so, I see these words,, "Of course if the real problem is the intake port is not moving the air and going turbulent"...........and wonder WHY this could be the problem. Is it heads? Intake? Cam itself? How can I tell if the head port is going turbulent?

I got 1 more shot on the dyno. One. And I have to absolutely fix this thing. I cant change heads. So everything else is a possibility.

Reversion as far as I understand is a cam issue. Hell, I'll change cams if need be, but it don't make sense. Tim at Bullet asked me every single build detail you could think of. If somebody said "change cams, all will be fine", id tear it apart tonite. and call Shane at Crower Monday.

Not sure what my plan of attack should be.

I have the exact same intake done by me the same way, on my current engine with a 640/640 lunati, 110 LSA installed at 104. Made a buttload more torque down low.

all that said, I still think I should have more lift at the valve. I'm checking my other engine when I get home. I'm betting I have somewhere around .627 (.640 minus .013 lash).

of course I might be wrong

If your current motor is making a buttload more torque, that should tell you something. You have a 110 LSA with the ICL 6* advanced. So, you are closing the intake valve earlier, and have less overlap from the wider LSA. That is trapping better quality air at low rpm and making more torque. The intake charge isn't as diluted, and the exhaust isn't over scavenging the cylinder during overlap.

If you call Bullet and talk to John, the owner, and tell him your combo and results, he will find more power.

 

[Ironmike]

If your current motor is making a buttload more torque, that should tell you something. You have a 110 LSA with the ICL 6* advanced. So, you are closing the intake valve earlier, and have less overlap from the wider LSA. That is trapping better quality air at low rpm and making more torque. The intake charge isn't as diluted, and the exhaust isn't over scavenging the cylinder during overlap.

If you call Bullet and talk to John, the owner, and tell him your combo and results, he will find more power.

will definitely do so Monday. Time is an issue, though. Honestly at this point, I'd rather buy some damn off the shelf cam that will run decent and call it a day. I'm so frustrated. Over there at Bullet, Tim is supposed to be the Mopar guy. Its like getting ahold of the president of the US. You know the deal, ship it back. Wait 6 weeks for a regrind. Then it sits on a shelf waiting to be shipped for a week.

Im thinking about buying a racehorse. It runs or it don't. Period.

 

[Cudafever]

If you could've given him a flow chart, for them heads, it would have helped Bullet pic a better cam.
You are Right, when you say that" the cam is what decides reversion". But! two different exh parts(porting) will require two different cams to keep the reversion out.
By looking at how much cfm your heads flow at low lift, you know how easy, or hard, it will to get rid of Reversion!!!!!
I know you are stressed for time, but if you could get some flow ### from them heads it would help with the next cam.
Even your dyno guy said that he didn't like how the exhaust port were ported. Some flow ### will help build the RIGHT cam for those heads.
With the dyno sheet, i'm sure the cam grinder can make some much better assumption. flow numbers would help also.....................

 

[Ironmike]

Hughes published flow numbers is all I have. They told me all their CNC stuff flows within 10 percent of the numbers. They can't flow every head they do, that's "costly and unnecessary with today's CNC equipment", according to them.

When I got them, of course I disassembled them to check the guides and just look around a bit. They looked real nice to me.....nice looking valve job, all valves same installed height, etc. I have no idea what good porting should actually look like. To my eye hell, they looked GREAT. The numbers on their website sure look good.

I'm still not convinced it's entirely a head issue. Have no idea what my next move is.

 

[superprotyrn]

I'm sending my eddy's to Ryan Johnson for 2.05's and cnc port and I live 3 hrs from Hugh's shop might buy they're rocker but thats it.

 

[70aarcuda]

I'm sending my eddy's to Ryan Johnson for 2.05's and cnc port and I live 3 hrs from Hugh's shop might buy they're rocker but thats it.

Modern Cylinder Head in Michigan....Does there own CNC porting in house......Can these other machine shops say that or do they outsource them?

 

[yellow rose]

First of all, you don't have enough cylinder head to open the LSA up. There have been published dyno pulls on this.

You are too wide at 108. Look at the mid numbers. They are down.

You are trying to fill a cylinder that is handicapped by not enough intake duration (or too much exhaust....what did they do...decrease intake timing or increase exhaust timing????) and then they open up the LSA to make the RPM carry past peak. You don't have a carry past peak problem do you? You have a mid RPM issue right? Harold Brookshire and I spent hours discussing this and HE wasn't big on blowing the LSA to make a cylinder head limited engine carry RPM.

On my BEST W-5 heads that went 365 CFM on a 2.100 valve with a 55 degree seat needed 278/282 at .050 to shift at 8800 on 340 CID. The only reason it had any split was I was on alcohol or the exhaust would have been 278. And that was on a 109 LSA.

The 1990's did more to screw up cam design and engine building than even the bullshit 1980's with its "swirl and tumble" porting nonsense.

You need to fax or email the dyno numbers to several cam companies and don't tell them whose cam it is and see what they all say.

You don't have enough head to move the LSA out any more. I'm the lone voice out there. Move the LSA out and it will kill the mids. Always does. When I see mid RPM numbers down the first thing I look at (if the RPM peak is where you want it) is LSA. Move it to 104 on a single pattern and out it 2 degrees advanced if you use a timing chain and watch it go big in the middle.

 

[j par]

I sure do appreciate your Forum Credit. I think anybody else would have been ran through the wringer for being disappointed with Dyno results? I've seen some people who really get the 5th degree for not liking their Dyno results. Someone was already b**** because they asked you a question that they felt was going to derail the conversation, but what the heck is this going in? and are you afraid that it's not going to do what you want it to in the end? Just curious...

="Ironmike, post: 1971594751, member: 11850"]Hughes published flow numbers is all I have. They told me all their CNC stuff flows within 10 percent of the numbers. They can't flow every head they do, that's "costly and unnecessary with today's CNC equipment", according to them.

When I got them, of course I disassembled them to check the guides and just look around a bit. They looked real nice to me.....nice looking valve job, all valves same installed height, etc. I have no idea what good porting should actually look like. To my eye hell, they looked GREAT. The numbers on their website sure look good.

I'm still not convinced it's entirely a head issue. Have no idea what my next move is.[/QUOTE]

 

[360duster]

I'd ask the head supplier about their cam choice for big power....they should have some data available as they claim these heads can make up to 725 hp. Then compare to yours.

Michael

 

[nm9stheham]

Not sure what my plan of attack should be.

all that said, I still think I should have more lift at the valve. I'm checking my other engine when I get home. I'm betting I have somewhere around .627 (.640 minus .013 lash).

I'd suggest that you work on the rocker ratio and lift since you can control and execute on that work right now; it may not be the main problem but if something is off, it sure is not helping. Like many new builds, there is often a combination of problems and you need to iron them out one at a time.

BTW, the Bullet master lobe catalog shows that they just multiply lobe lift by rocker ratio to get to valve lift numbers, so using all the corrections is needed to get to what you really will see.

Now you want to make me go and check on some Hughes 1.6 rockers that we have.....

 

[RAMM]

Hughes published flow numbers is all I have. They told me all their CNC stuff flows within 10 percent of the numbers. They can't flow every head they do, that's "costly and unnecessary with today's CNC equipment", according to them.

When I got them, of course I disassembled them to check the guides and just look around a bit. They looked real nice to me.....nice looking valve job, all valves same installed height, etc. I have no idea what good porting should actually look like. To my eye hell, they looked GREAT. The numbers on their website sure look good.

I'm still not convinced it's entirely a head issue. Have no idea what my next move is.

10% !!!!!!!!!!!! that's like 30 cfm!! Good God. I hold whole engine quotes to +/- 3%

I guess that's where I've gone wrong!! 10% hilarious.

So by Hughes' own words---"Costly and unnecessary with today's CNC equipment" Jesus--They say its accurate because of CNC but give 10% variance 'cuz it could be different!!!??? That's fuckin hilarious! J.Rob

 

[RAMM]

I'd ask the head supplier about their cam choice for big power....they should have some data available as they claim these heads can make up to 725 hp. Then compare to yours.

Michael

725HP small block?! Bwahahahahahahaa !!! Give me a bloody break. It is near impossible to break 600 REAL HP on pump gas with a NON-W headed small block--don't care about the cubes. 725HP Again shaking my damn head. Somebody needs to give certain people a goddamn shake so hard they reverse their brain damage. Anyone shows me a small block cracking 625 hp on pump gas and I'll find where their dyno is fucked up in about 2 minutes. J.Rob

 

[IQ52]

So if they are flowing within 10%, they could be flowing 284cfm @ .650"? Or is it 274cfm @ .650"? Which heads really? The big mouth heads are listed at 316cfm @ .650 and the fully cnc'd heads are 304cfm @ .650". 90% of those flows is......well......284 or 274.

Not that it isn't the cam, just wondering.

 

[nm9stheham]

First, the pushrod angle changes as it goes through the lift cycle. The more lift, the more extreme the angle, so there is no magic number to plug into the trig formula. It is usually more than 11*, especially with a roller lifter.

Yes; in this case even if the angle varied from 11* to 15* at the top of the lifter stroke (which I suspect is exaggerated), that increases the pushrod stroke loss by about .003" vs. assuming a constant 11 degree pushrod angle. The point Mike needs to know is that this loss is part of the deal and is not insignificant.

Mike, the way you measured, at the top of the pushrod, would have taken all this into account. So your .409 at the top of the pushrod sounds pretty close to account for the pushrod angle. And you're right, it is hard to get the indicator plunger exactly inline.

 

[RAMM]

So if they are flowing within 10%, they could be flowing 284cfm @ .650"? Or is it 274cfm @ .650"? Which heads really? The big mouth heads are listed at 316cfm @ .650 and the fully cnc'd heads are 304cfm @ .650". 90% of those flows is......well......284 or 274.

Not that is isn't the cam, just wondering.

It's not the goddamn cam on its own. I'm just gonna say it--The heads ain't the power producing beasts you think they are. I have the BIG csa heads and they still don't move air the way they should. It's not just the numbers, its the way they sound and the shape of the curve.

I built a 417--with Max ported EQ's and custom roller cam--made 581 hp / 563 tq. Wasn't happy with the power down low, (IT WAS JUST LIKE YOURS IT MADE 400-440 TQ FOREVER AND COULDN'T GET OUT OF ITS OWN WAY UNTIL ABOUT 4800 RPM)put a smaller Lunati Voodoo roller and W2 heads that flowed LESS and made an easy breezy 590 HP / 574 tq! Still didn't crack 600HP and I really wanted to. It's time somebody said it. 600 HP small block on pumpgas ain't happening with a standard port head no way -no how for the average man and budget. And I'm average. J.Rob

 

[RAMM]

Mike , I know you are frustrated because I'm frustrated just reading and reliving my own experiences.

That cam is wrong, but until you fix/change the heads NO cam will give you what you want. I don't even care if you're chasing a dyno number. That engine as it is will SUCK if you don't treat it like a 340 (5000 stall/4.56 gear type stuff) You need to send your heads to a PRO like Vic Bloomer or Brett Miller and then you can stick almost ANY cam in and watch those dyno numbers grow AND the car will respond in kind. J.Rob