Another internet myth bites the dust... LS7 vs. LS1 lifters
06-22-2011, 10:21 AM
#21
FormerVendor
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"TEH INTARWEBZ" is a big, scary, dangerous place...
I have no idea what people are measuring. I've done 5 cam swaps in the last 2 weeks. All cars left with nice quiet valvetrains, no valve float, and killer power numbers...
Shane
I have no idea what people are measuring. I've done 5 cam swaps in the last 2 weeks. All cars left with nice quiet valvetrains, no valve float, and killer power numbers...
Shane
06-22-2011, 12:09 PM
#24
to bust a myth, don't we need hard evidence to put it to rest? without it, it could end up called out as a myth and replaced with another myth.
lifters in question
(predator-z's pictures)
for what its worth,TSP advised the LS7 lifter was taller. with milled heads, LS7 lifters, gaskets and my 228R, they guessed pushrod length range (although they stressed that i needed to measure to be sure in any setup) and it turned out to be accurate.
IMO, we've got at least 2 reputable companies with differing views on this.
lifters in question
(predator-z's pictures) for what its worth,TSP advised the LS7 lifter was taller. with milled heads, LS7 lifters, gaskets and my 228R, they guessed pushrod length range (although they stressed that i needed to measure to be sure in any setup) and it turned out to be accurate.
IMO, we've got at least 2 reputable companies with differing views on this.
06-22-2011, 12:24 PM
#25
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If it was measured from roller to cup, then that's it. No more discussion, because that is the overall length the valvetrain "sees". If someone is referring to the countersunk distance of the cup into the top of the lifter, then that's irrelevant. That is what I thought everyone referred to when saying the LS7 lifter was taller.
06-22-2011, 12:37 PM
#26
Thanks, Guys. I've always known it was a myth because I check lifter preload on every cam swap I do. The results have always told me the pushrod cups had to be the same distance from the camshaft. Its just that no one ever wanted to believe me! I guess 100+ cams swaps a year don't count for much when you're trying to make appropriate component recommendations...
Shane
Shane
06-22-2011, 04:20 PM
#28
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I'm still F***in confused, I've been told again by another very knowledgeable builder that the 7.425s will work if the heads aren't milled, but 7.4s might be better, 7.375 may be to short. HELP!!!!
06-22-2011, 06:23 PM
#31
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FWIW Im running 7.375 rods in my LQ4 with stock head gaskets, stock 317s and a gt2-3 cam. I measured the pushrod length and am running .06 preload. Seems to me theyre a little different... Either way, my engine is very quiet and makes good power so Im happy.
06-23-2011, 11:13 AM
#34
06-23-2011, 03:24 PM
#36
I can add that I went through this same dilema when I was putting new LS7 lifters in with my PatG spec'd EPS cam. Pat had spec'd me to use 7.425 pushrods with the cam, but I didn't know if swapping to the LS7 lifter would change things or not. According to Pat, the preload is the same between the LS1 lifter and the LS7 lifter, and the 7.425 pushrods would be fine to use. I rolled with it, and everything worked out great.
06-23-2011, 09:49 PM
#37
The original poster may or may not be right. I don't know. However it would seem to me that the correct way to measure would be to put the same pushrod in each lifter and measure from the bottom of each roller to the top tip of the pushrod and see if they are in fact the same length. I think how the pushrod sits in the cup may be the deciding factor.
06-23-2011, 11:35 PM
#39
"Why would GM replace a lifter from 87 on up with another lifter that would require a different length pushrod?"
If the difference is small enough it may not really be a big deal especially with factory tolerences. However if building a new motor one needs to check the pushrod length anyways as there are a variety of components that can change things depend on what was selected for the build including different brands such as aftemarket heads.
If the difference is small enough it may not really be a big deal especially with factory tolerences. However if building a new motor one needs to check the pushrod length anyways as there are a variety of components that can change things depend on what was selected for the build including different brands such as aftemarket heads.
Last edited by 1989GTA; 06-24-2011 at 01:34 PM.
06-24-2011, 12:26 PM
#40
Most lifter manufacturers (me being one of them) have extended and collapsed lengths measured from the tip of the roller to the tip of a ball bearing sitting in the radius of the pushrod seat. The standard is a .375 or .3125 diameter ball, my prints spec lengths using both. I don't have an LS1 lifter in front of me, but I do have an LS7. My extended length measurements are about 2.647 over a .3125 ball. I'm going to get an LS1 lifter tomorrow and see what I find.