Using the Comp Cams pushrod length checker that my friend bought from TSP. Didn't come with intructions.

But he has a Lq4 block with P&P 317 heads milled .015", Ms3 cam, .675" springs and full bolt ons. He used the stock sized 7.4" pushrods and they made a sewing machine sound. He got th PR checker to see what size he should be getting cuz of the noisy valvetrain.

We read the ThunderRacing method of checking the pushrod length and we are getting 1 and 1/4 turns when we tighten the rocker arms to 22lbs. When the length is at 7.4 according to the PR checker is 1 to 1and 1/4 turns. When we set the PR checker to 7.375 we get 3/4 to 1 turns. So what size are we supposed to use?

Help.

 

We are using the Eo/Ic method, and to clarify my question cuz it really isnt clear, what size Pushrod should we be using?

 

I don't have directions from mine, but this is what I recall from when I did mine last. Make sure your on the base circle of the lobe your checking. Each full turn of the PR length checker is worth .050, its markd with two dashed lines. The PR length checker is 6.80 compressed. You open the PR checker until you take all the slack out and it is sitting in the cup of the rocker. Count your turns, then add your lifter preload. Thats how I did mine with the pushrod length checker.

 

Thanks for the info I forgot to ask that too, lol. But yeah we are getting 1 and 1/4 turns is that right if we are on the 7.400 setting on the PushRod Length Checker?

 

To get to 7.400 on the PR Checker would be 12 full turns. It starts out at 6.8. 12 x.050= 6.00 which would bring you to 7.4 . How many turns from 6.8 does it take to put the tip of the PR checker to the cup of the rocker?

 

1-1/4 turns on the rocker bolt is approximately 0.068" of rocker preload. What is your zero lash measurement? Should be around 7.330" gauge length.

 

Thanks guys for the quick responses i should of added that we were doing this as we typed along. The process was easy the sound is virtually gone I just cant believe the noise is gone on such a large cam AND milled heads, we were certain befor ethe build that if anything the Pushrods would HAVE to be small. But no, sewing machine sound gone, tuning next month I will post up the sheet soon. Now to build my car...

 

well what size did you go with????

 

Ended up with a 7.425" pushrod