Pushrod length... need some help
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Joined: Nov 2003
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From: St.Louis, Missouri
Pushrod length... need some help I built a LS1 about a year ago for my '91 GTA and I've just now got it installed and I'm trying to iron out all the small issues before initial startup. A question has come to mind recently though.... pushrod length. Here is my setup....
-'98 LS1
-ported/polished '98 heads
-newer style '99 and up valves
-TR Reverse split cam
-stock rotating assembly (with ARP rod bolts)
-stock lifters
-stock head gaskets
-TR 7.4 hardened pushrods
-stock rockers
-comp 918s with titanium retainers
-LS6 intake, pulley, headers... blah blah blah
*Anyways, my friend that ported the heads for me couldn't remember if we milled the heads or not. I can't blame him at all... it's been a long time ago and I can't remember either. At the time when I built it I thought everything was ok, but now I'm concerned with the PR length. IF we milled the heads, we would've taken .030" off them. I've read some posts on here saying stock pushrods are actually 7.38" and that TR 7.4's are actually 7.415" which is what is in the motor.
**So if in fact we did mill the heads .030" and everything else stayed the same, then I lost .030" from the head, but gained .035" from the pushrods. I also spoke with TR and they said they use their 7.4's with anything up to .030" milled heads. So how do I know if I'm ok or not? Someone mentioned measuring something on my heads (to see if they were milled), I've also heard about taking the rocker to 0 lash, then counting how many turns until I hit 22ft/lbs (to determine if I need shorter/longer PR's), and then I guess there is always a pushrod length checker but I don't have one.
Any help is GREATLY appreciated.
thanks!
-Jeremy
-'98 LS1
-ported/polished '98 heads
-newer style '99 and up valves
-TR Reverse split cam
-stock rotating assembly (with ARP rod bolts)
-stock lifters
-stock head gaskets
-TR 7.4 hardened pushrods
-stock rockers
-comp 918s with titanium retainers
-LS6 intake, pulley, headers... blah blah blah
*Anyways, my friend that ported the heads for me couldn't remember if we milled the heads or not. I can't blame him at all... it's been a long time ago and I can't remember either. At the time when I built it I thought everything was ok, but now I'm concerned with the PR length. IF we milled the heads, we would've taken .030" off them. I've read some posts on here saying stock pushrods are actually 7.38" and that TR 7.4's are actually 7.415" which is what is in the motor.
**So if in fact we did mill the heads .030" and everything else stayed the same, then I lost .030" from the head, but gained .035" from the pushrods. I also spoke with TR and they said they use their 7.4's with anything up to .030" milled heads. So how do I know if I'm ok or not? Someone mentioned measuring something on my heads (to see if they were milled), I've also heard about taking the rocker to 0 lash, then counting how many turns until I hit 22ft/lbs (to determine if I need shorter/longer PR's), and then I guess there is always a pushrod length checker but I don't have one.
Any help is GREATLY appreciated.
thanks!
-Jeremy
You are going to have to check the pushrod length to be dead nuts on. You could always CC the Combustion Chambers and tell if they have been milled but that would of course require taking the heads off.
