Pushrod length checking questions
In this thread Patrick G suggests .080-".100".
And I'm not saying that is incorrect. I think it depends on what hardware you are running. I know it was definitely incorrect for my combination. And I know Comp recommends a much shallower depth according to the tech article they sent me. But for Patrick's combinations, it may be exactly what you need.
I put a 7.35 back in tonight and re checked it. I had a friend help me. I turned the pushrod lightly in my fingers till zero lash as he tightened the bolt. We both could tell at the same time where zero lash was.
On the intake I got 1 1/2 till snug. It was probably a little bit more to get to 22ft lbs. I didn't have my torque wrench tonight.
We did this at least 1/2 a dozen times and got the same thing everytime.
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Disregard the this part of the previous post as I had been partaking in the Bud Liteus' and forgot to put the 7.350 pushrod in. I got to thinking about it today and decided it was pretty much impossible to have 2 1/4 turns with a 7.35 pushrod. I'd have like 3.5 turns if that was the case with the 7.4
I put the 7.35 in on the exhaust side today and I get 1 1/4 turns snug, not torqued. I remembered the two being different now I know how.
On the intake I got 1 1/2 till snug. It was probably a little bit more to get to 22ft lbs. I didn't have my torque wrench tonight.
We did this at least 1/2 a dozen times and got the same thing everytime.
--------------------------------------------------------------
Disregard the this part of the previous post as I had been partaking in the Bud Liteus' and forgot to put the 7.350 pushrod in. I got to thinking about it today and decided it was pretty much impossible to have 2 1/4 turns with a 7.35 pushrod. I'd have like 3.5 turns if that was the case with the 7.4
I put the 7.35 in on the exhaust side today and I get 1 1/4 turns snug, not torqued. I remembered the two being different now I know how.
Last edited by LilJayV10; Sep 5, 2011 at 04:37 PM.
One thing i think the LS7 lifters has is a bit more engineering. They "allow" more preload. (Also deeper cup) But what I actually think from the hours of **** I read on this, is that the LS7 lifters were designed to handle more rpms. Therefore, more pumping of the lifter will occur at higher rpm. I think they engineered more room for the pump up at higher RPM. I will be running at the intended RPM for these lifters. So I will only put in minimal preload. Therefore the room for pump up will be taller and safer for higher rpm use before they lock up tall from the pump and bend my rods. And yes. The Comps have different lifters with different preload requirements.
There seemed to be a lot more turns on the exhaust but without doing it the same way as the exhaust I can't say if it's accurate. It was closer to 2- 2 1/4. I'm wondering if when I had the 7.350 in there the intake was right but the exhaust was loose. When I put the 7.4 in there it quieted down the exhaust but the intake might have not have enough preload. I will verify the exhaust tomorrow.
Delete post due to alcohol consumption while testing push rod length.
To recap w/ 7.35 push rods I have a little over 1 1/2 turns on the intake and a little over 1 1/4 turn on the exhaust. These are just snugged not torqued. Using hiltsy855 chart that still puts me in the .074-.093 range which is better where I'm at now.
To recap w/ 7.35 push rods I have a little over 1 1/2 turns on the intake and a little over 1 1/4 turn on the exhaust. These are just snugged not torqued. Using hiltsy855 chart that still puts me in the .074-.093 range which is better where I'm at now.
Last edited by LilJayV10; Sep 5, 2011 at 04:40 PM.
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Verdad Gallardo I get different numbers from my chart. If you're ~= 1.55 turns to snug on the intake then you'd have about 1.85 turns to 22 ft. lbs. = .122" preload. If you're ~= 1.3 turns to snug on the exhaust then you'd have about 1.6 turns to 22 ft.lbs. = .100" preload. I'd look at shorter pushrods on the intake at a minimum.
Instead of trying to figure out how deep you are into the lifter by computing through the rocker ratio, go buy a couple of adjustable pushrods. They aren't that expensive and you can get an accurate measurement that way.
I'm surprised I need that short of a pushrod but it is what it is. On all SBC's I work when I adjust the valves I normally go 3/4 turn preload. If found this is a good compromise when running a cam. I don't know why I didn't look at it the same way. I have an adjustable push rod I'm going to use today and see what I end up with.
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Did some more checking on a cylinder where the lifters were still pumped up.
Intake
7.300 3/4 turn
7.325 1 turn
7.350 1 1/4 turns
Exhaust
7.300 1 turn
7.325 1 1/4 turn
7.350 1 1/2 turns
I think I was over complicating the whole process before. After doing it this time and taking time to write my results down and understanding what they actually mean makes everything much easier.
Thanks to everyone who has taken the time to help me.
Intake
7.300 3/4 turn
7.325 1 turn
7.350 1 1/4 turns
Exhaust
7.300 1 turn
7.325 1 1/4 turn
7.350 1 1/2 turns
I think I was over complicating the whole process before. After doing it this time and taking time to write my results down and understanding what they actually mean makes everything much easier.
Thanks to everyone who has taken the time to help me.
Last edited by LilJayV10; Sep 6, 2011 at 11:33 PM.
I talked to Geoff@EPS today. He told me for a stock LS1 lifter to get between .040-.080. I was on Comp's website today looking around and some of their lifters are .005. When I built a friends LT1 engine he used the Comp R lifters. I tried to adjust them w/ 3/4 turn like a stock lifter and they were noisy as hell. Comp said they need like a 1/16 of a turn. I did that and they sounded much better.
I checked the preload a few more times on the #3 cylinder and the lifters felt the same way as #1 did. Disregard my previous comments about the lifters.
Last edited by LilJayV10; Sep 6, 2011 at 11:31 PM.
I really believe it depends on the camshaft (lobe design) and springs as to what the ideal preload should be. But the more I play with these, the more it appears the least amount of preload you can get away with, the better.
