Verify proper pushrod length
Verify proper pushrod length I'm in the process of checking PTV clearance using the "clay method". I had my buddy weld the old lifters (so they won't collapse) for the test. I have Harland Sharp rocker arms, and noticed that it seemed like there was about 1/8" of a gap before the rocker pedestals get tight on the bosses. After tightening it all the way, the valves have moved considerably. So I'm wondering if my pushrods are too long, or if I need shims under my rocker arms. Which do you do first? Shim the rockers, or check/change the pushrod length?
I used an online pushrod calculator and based on my base circle of my cam (1.455"), and my heads being milled .030", it came up with a new length of 7.400". I also have LS6 valves which are .6mm longer or .0236". So, I subtracted that from the 7.400" and come up with 7.376". I purchased 7.375" pushrods. Stock .052/3 GM gaskets. Should I be ok?
I used an online pushrod calculator and based on my base circle of my cam (1.455"), and my heads being milled .030", it came up with a new length of 7.400". I also have LS6 valves which are .6mm longer or .0236". So, I subtracted that from the 7.400" and come up with 7.376". I purchased 7.375" pushrods. Stock .052/3 GM gaskets. Should I be ok?
Last edited by Teutonic Speedracer; Jan 7, 2006 at 06:43 PM.
I would just check the pushrod length with the regular lifters. Then you can either use a dial indicator or see how many turns it moves to see how much preload you have when the rockers are tightened down. I guess if you want to do it with the solid lifters in for some reason you could use a dial indicator on the valvespring side to see how much the valve opens and then divide by 1.7 to get lifter preload.
Originally Posted by P Mack
I would just check the pushrod length with the regular lifters. Then you can either use a dial indicator or see how many turns it moves to see how much preload you have when the rockers are tightened down. I guess if you want to do it with the solid lifters in for some reason you could use a dial indicator on the valvespring side to see how much the valve opens and then divide by 1.7 to get lifter preload.
I'm thinking that I should check and adjust the preload on the replacement lifters, then after that is adjust put my welded ones in and then check the PTV clearance?
I agree with that, although you could do it at the same time if you check P to V on one cylinder and preload on other cylinders to save you the trouble of pulling the heads one more time.
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