Figuring out pushrod length ?
Figuring out pushrod length ? I'm having p to v clearance issues and i think i might have the wrong pushrod length so I need some help. I have 5.3 heads milled .030 with 2.02 1.57 valves and a x 1 cam. I'm using stock length pushrods and I think I should have shorter can anyone tell me If I do or not ?
TIA
Marc
TIA
Marc
Re: Figuring out pushrod length ? nope...you have the right length pushrod...
Most aftermarket cams have about a .030" smaller base circle. So if you had just changed the cam shaft (no heads), you would have needed a pushrod that was 7.430" long. If the piston rod were too long, the valve would NEVER close.
Since you have the 0.030" mill on the heads, everything cancles out.
Chris
Most aftermarket cams have about a .030" smaller base circle. So if you had just changed the cam shaft (no heads), you would have needed a pushrod that was 7.430" long. If the piston rod were too long, the valve would NEVER close.
Since you have the 0.030" mill on the heads, everything cancles out.
Chris
Re: Figuring out pushrod length ? I was just making sure I had the right length I would never install something shorter. I found the tool to fly cut pistons and I'm going to do that and hope the stock pistons hold up. Luckily I'm already working on my next motor so as long as it holds till than I'll be good. Thanks for all the info though.
Marc
Marc
Re: Figuring out pushrod length ? Ok....it had come up on the other post and I didn't know if you ment that or not.
Let me know how that tool works (how hard it is to deal with). I considered doing that but just was not "ready" to do that yet.
good luck,
Chris
Let me know how that tool works (how hard it is to deal with). I considered doing that but just was not "ready" to do that yet.
good luck,
Chris
Re: Figuring out pushrod length ? I would check pushrod length anyways.I run .030 off my heads and a tr224 cam.Needed to use 7.350 pushrods.Could of gotten away with 7.40's but the lifter was compressed .10.I'm thinking alot of people are running 7.40's when they should really run 7.350's.The longer will work but can result in lower power output by hanging the valve a little at high rpm.It's very easy to check.Bolt on rocker till 0 play in pushrod,then put dial indicator on pushrod end of rocker.Tighten rocker down to 22 ft/lbs and see how much it collapses the lifter.You want around .035-.055. but can get away up to .10 if desperate.
Re: Figuring out pushrod length ? Well I'm not the only one with this setup but i dont know why mine wont work maybe because of my huge valves but Camaroguy is right it has to equate to 7.4 and everything does but it hits so I have to fly cut the pistons which I hope to get the tool soon.
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Re: Figuring out pushrod length ?
I would check pushrod length anyways.I run .030 off my heads and a tr224 cam.Needed to use 7.350 pushrods.Could of gotten away with 7.40's but the lifter was compressed .10.I'm thinking alot of people are running 7.40's when they should really run 7.350's.The longer will work but can result in lower power output by hanging the valve a little at high rpm.It's very easy to check.Bolt on rocker till 0 play in pushrod,then put dial indicator on pushrod end of rocker.Tighten rocker down to 22 ft/lbs and see how much it collapses the lifter.You want around .035-.055. but can get away up to .10 if desperate.
If you take a bone stock LS1...Remove a valve cover (drivers side is easy)...Turn the engine until one of the valves is fully closed (#1 would be easiest)...Then loosen the rocker until is very loose...Then tighten it until your at zero preload (bolt will all of a sudden get hard to turn)...Mark the boilt with a scratch mark...Turn the bolt down till its at 22 FtLb torque.
You will find it turns between 1 3/4 to 2 turns on that stock LS1 engine.
It should do the same thing after you finish your head/cam install (or very close to it). If not, you are a candidate for different pushrods.
Now, how much preload is 1 3/4 to 2 turns? I don't have a clue, but thats what the stock GM preload is on the LS1. At least thats what it was on my 98 TA [prior] to changing out parts.
Ron,
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Re: Figuring out pushrod length ? BTW, if it was my engine, I would rather have it at maybe 1 1/4 to 1 1/2 turns.
Nothing greater than 2 turns. I say that because slightly less preload will keep the lifters from pumping up at high rpm quite so fast.
Remember, hyd. lifters can operate at a fairly great variation of preload (up to a point)...
Nothing greater than 2 turns. I say that because slightly less preload will keep the lifters from pumping up at high rpm quite so fast.
Remember, hyd. lifters can operate at a fairly great variation of preload (up to a point)...
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Re: Figuring out pushrod length ? So what is the verdict? I'm getting ready to build my motor and I'm looking at the same issue. My heads are milled .030. New cam 222/222 .563.... I have already bought hardened 7.4" pushrods, but have not installed them yet. Do I stick with them or exchange them for 7.35".
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Re: Figuring out pushrod length ? The Thunder 7.40" rods were measured by me to be .015" longer than the stock rods.
With your combo, either the the 7.40" or 7.35" will work, but the 7.50" will get you closer to the stock spec preload.
With your combo, either the the 7.40" or 7.35" will work, but the 7.50" will get you closer to the stock spec preload.
Re: Figuring out pushrod length ?
So what is the verdict? I'm getting ready to build my motor and I'm looking at the same issue. My heads are milled .030. New cam 222/222 .563.... I have already bought hardened 7.4" pushrods, but have not installed them yet. Do I stick with them or exchange them for 7.35".
