I've asked two guys the size they ordered and both said 7.425.

Does anyone know the length off hand that would be ideal without measuring?

I've never used the measuring tool, so that would be ideal right? But if you have the el torro please tell me what size you used.

A certain shop sent me the wrong ones so i need to make sure 7.4 is in fact too short before I send them back.

Thanks

 

from what i hear a pushrod length tool is pretty easy to use, just tighten down to specs, turn over the motor and the die should tell you where the pushrod should be touching, you adjust until its at optimal height. Im sure if you ask around though you'll get a majority and you can go from there. Considering that everything is the same setup as yours

 

It's been so long since mine went on but IIRC I used 7.4's......

 

I'm installing a tweaked version of one right now with 2 more degrees exhaust duration and on a 110 LSA (230/232 110+1). I measured my pushrod checker this morning off a granite plate and with a 7.411" pushrod checker length I was getting almost 1 full turn on the rocker bolt when torqued down. I belive the rule of thumb is .047" of preload per turn of the rocker bolt, so a 7.425" pushrod should give me ~.060-.065" of installed preload. This is on a stock 2000 LS1 with 853 castings.

 

This is assuming you have the Comp Cams adjustable pushrod, which at its shortest length is 6.800".

Each turn of the adjustable pushrod is 0.050". When fully closed, it is 6.800". This is pushrod "gauge length" so you can't measure it directly as the pushrod length is actually based on the length between the ball ends where the ball end measures 0.140" in diameter. Assuming you are using stock rockers or a non-adjustable rocker.

1. Open the adjustable pushrod to the same length as your stock pushrods
2. Close it down two turns
3. Put your rocker rail on the head
4. Make sure you cylinder (typically #1) is at top dead center on the firing stroke so both valves would be closed
5. Put the pushrod in place on the intake valve and make sure it is in the lifter cup
6. Install the rocker and snug down the bolt (don't need to torque, just make sure it is snug)
7. Lift rocker tip up and down, if it "ticks" the pushrod is too short. If you can't easily move the rocker the pushrod is too long.
8. You can try and adjust the pushrod in place but my fingers are too fat so I end up pulling the rocker and adjusting the pushrod length. Go either shorter or longer 1/2 turn and try again.
9. You are trying to get to the point where the lifter doesn't "tick tick" with the pushrod in place nor is the rocker snug. When you get the pushrod length such that you just barely get rid of the "tick tick", you have found "zero lash".
10. When you have found zero lash, carefully remove the rocker and pushrod without rotating the pushrod.
11. Tighten the pushrod until it is fully closed counting the turns as you go.

To figure out your pushrod length you do the following. Let’s assume it took 10-1/2 turns to close the pushrod down to its shortest length after you reached zero lash. Each turn is 0.050".

Your length is then: 6.800" (fully closed length) + 10.5 X 0.050" (number of turns times the length change per turn) = pushrod length minus preload. So for this case:

6.800 +10.5 X 0.050 = 7.325"

This is the length you measured to zero lash without any lifter preload. Now let’s say you want to have 0.075" lifter preload, you add that to the measured number and you end up with 7.400" pushrods.

Now repeat for the exhaust valve to verify the length. If you have something like Yella Terra's, it is the same procedure but you must snug down the rocker pair rather than the single rocker.

 

It will give you closer to 0.072".

 

I ran 7.400 in my car and they were on the edge of being to short...try will work but I always recommend 7.425 for cam only setups using stock unmilled and mls gaskets

 

Did you measure Chris?

I think that's what I'm going to go with, but if not. I might just measure to make sure.

 

I rechecked last night using the method vettenuts posted above. On the intake lobe 11 turns of the adjustable pushrod was perfect - the lash went to zero just as the rocker bolt was fully snug. That corresponds to a 7.425" pushrod using .075" preload (you're right VN - I had .072 the other way). On the exhaust lobe 11 turns was too tight, so I backed it off to 10.5 turns which was a shade loose. I was able to fit a .013" feeler between the rocker and valve tip, so that tells me that my adjustable pushrod at 10.5 turns was .013"/1.7 or about .008" too short for a true zero-lash. I think I'd rather run a 7.400 pushrod with .067" preload vs. a 7.425 with .092", so it looks like I'm going to order two lengths - 7.425 intakes and 7.400 exhausts. I verified I was on the base circle with the EO/IC method.

John

 

Thanks guys, this helps out a lot.

 

Sounds right since that cam uses different intake and exhaust lobes.....

 

i used 7.425 like chris said.