Yet another pushrod thread, but I am not asking how to do it.

I am using the comp cam magnum checker. I have an lq9, l92 heads, both are unmilled. I installed the checker tool and torqued the rocker to 22 ft lbs. Twisted the tool until no ticking was heard. I pulled the tool out and measured it comparted to the 7.4 comp cam pushrods I had. The tool was .15 shorter.

Would this make it

7.4- .15= 7.25 + .080(preload ls7 lifter) = 7.33, so round up to 7.35 pushrods?

Any comments or suggestions appreciated

 

Did you mean "zero-lash"? If so, it sounds like you are on the right track.

We generally shoot for .050" preload, but anywhere between .030" and .080" should be ok. Shoot me a pm or give us a call if you have any other questions.

 

Looks right, but does the length checked not have markings on it. The comp one does, which I always use.

 

Yes, Zero lash is what I meant. If I add .050 for preload its 7.3 exactly.

Its the comp cams magnum checker. Comp cams says with this one you adjust to zero lash and measure the difference between a known length rod (I already bought comp cams hi tech 7.4" pushrods and used them as comparison). I got .15 difference.

 

The LS6 camshaft has a smaller base circle, but 7.300" sounds too short with both unmilled heads and undecked block. Although, there are so many variations in factory blocks and heads that this is why we always advise to check pushrod length when changing any valvetrain component.

 

I went and rechecked all the cylinders in the drivers side multile times. All came out .12 to .15, no shorter or longer. compared to the 7.4, so 7.25 to 7.28 before preload is added.

I did buy the heads used bare, so as far as I know, they were not milled but that could have been by the previous owner. I really didn't think about it until now.

7.4 was too long, at base circle the lifter was getting depressed before the rocker was threaded all the way down.

 

I think I used 7.325 on my milled l92 heads...

 

The lifter will depress, that is what gives you your pre-load. How much is the pre-load? You don't want the valve moving at base circle when the rocker is being tightened down if that is what you were thinking.

 

After taking measurements on all of the drivers side cylinders I believe preload is between .080 to .060 on all, no more then .080 though. The lengths needed to get zero lash were between 7.25 and 7.27, adding .060 to .080 on preload puts them at or near 7.35. It took some reading and doing it myself to comprehend the math, but I think I have it.

again thanks to all who responded.

 

Ok, guys I got the engine running and I still think I might have pushrod issues. There is not much noise outside, but its a loud sewing machine on the inside. I used 7.350. I'd like to find a local who builds and modifies LS engines, but I havent had much luck.


running after exhaust - YouTube