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2004 GTO H/C/I. 430whp (hub dyno)
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240 Posts
Discussion Starter · #21 ·
Make sure the lifter is on the base circle of the cam. Install the pushrod tool with teflon tape on the tool's threads. Torque the rocker to 22 ft-lbs, and then run the tool up until lash is taken out (the tool no longer wobbles up and down between the rocker and the lifter). Remove the rocker and carefully remove the tool so as to not accidentally turn it and mess up your measurement. Using 8" calipers, measure the length of the tool. Do not count turns or any other stupid method the broke-dick internet bros tout because they can't afford a $60 tool. Take that measurement, add your desired preload, and you have your needed length.
Thank you for your help. I haven't got to re measure yet. But I bet I was definitely compressing the pushrod when I was putting the tool in anyways. Project car for a reason haha
 

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2004 GTO H/C/I. 430whp (hub dyno)
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240 Posts
Discussion Starter · #22 ·
Update. I ended up working the weekend. So today was the first day I got to try everything you guys recommended and mentioned. I did some of my own research and came to the conclusion the E.O.I.C was the best way to find base circle without accidentally screwing it up.
So in this video I posted was me resetting and cranking over the engine till the exhaust valve opened. Then I would proceed with putting my pushrod checker in and torque it down to 22ftlbs. This was with a 7.060 length to find zero lash( not preload). As you can hear after I torqued it down. I had some very little lash. Yes I've done this process now about 50 times. I'm going insane. Again I appreciate all your guys support in the forums.
 

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2004 GTO H/C/I. 430whp (hub dyno)
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240 Posts
Discussion Starter · #24 ·
Well I finally went through every cylinder. I double checked all of them. Thank you guys for all your help again.
Intake-7.080 ( zero lash)
Exhaust-7.135 (zero lash)
Guess that's the end of that at least.
 

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2006 Pontiac GTO
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178 Posts
Hubert is getting you down the right road. You don’t torque your rocker arm down checking for pushrod length. If you’re loading the lifter, your length measured is too long. When checking push rod length you’ll measure on the base circle (valve completely closed), put your length checker tool in the hole, ex: at 7.4”, make sure it’s in the cup, put the rocker on the pedestal and you should be able to just put the bolt in and get it just to a tad past hand tight. If there is play in the push rod, you’re too short and you start all over again. Keep going until you don’t have any more play in the push rod. Then you’ll add the suggested preload for the lifter and the thickness of the head gasket and that’s your push rod length. There are some pretty good videos on YouTube showing this procedure as well.
 

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2004 GTO H/C/I. 430whp (hub dyno)
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240 Posts
Discussion Starter · #26 ·
Hubert is getting you down the right road. You don’t torque your rocker arm down checking for pushrod length. If you’re loading the lifter, your length measured is too long. When checking push rod length you’ll measure on the base circle (valve completely closed), put your length checker tool in the hole, ex: at 7.4”, make sure it’s in the cup, put the rocker on the pedestal and you should be able to just put the bolt in and get it just to a tad past hand tight. If there is play in the push rod, you’re too short and you start all over again. Keep going until you don’t have any more play in the push rod. Then you’ll add the suggested preload for the lifter and the thickness of the head gasket and that’s your push rod length. There are some pretty good videos on YouTube showing this procedure as well.
Well initially I was fudging it all up. Thank God Hubert called it out on what I was doing. So since then I did allot more researching. Actually figured it out. I measured every valve twice. Intake and exhaust are different lengths. But across all the cylinders they're the same. The original builder of this engine must of just slapped the pushrods that came with the cam kit in it (7.450) (ls1 stock lifters)
I used the same gasket brand new. But I did change the lifters to morel 7717 ls7 style lifters. So I think that's why my length changed drastically. But the engine did have allot of valve train noise before I took it apart. My tuner also said it sounded like the preload on the stock lifters was way off. But I'm gonna slap in the new pushrods and if she blows well I'm parting it out lol. Jk it ain't gonna blow. I measured way to many times to have fudged it up and had allot of help along the way.
 
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