LS7 lifters
03-20-2010, 08:48 PM
#31
OK, well why are these LS7 lifters advertised as a direct replacement lifter for all LS engines?
I bought 7.400 pushrods for my cam with stock lifters, so by purchasing the LS7 lifters which are " direct replacement" why would i need to worry about the new rods i bought bieng the wrong size??
Damn it why is it so difficult to buy parts that work together without having to check and double evry spec?
PART 2 ---
So say if i want to buy new stock replacement lifters for my LQ4 are they going to be the LS7 ones now ???
Just a bit confused.
I bought 7.400 pushrods for my cam with stock lifters, so by purchasing the LS7 lifters which are " direct replacement" why would i need to worry about the new rods i bought bieng the wrong size??
Damn it why is it so difficult to buy parts that work together without having to check and double evry spec?
PART 2 ---
So say if i want to buy new stock replacement lifters for my LQ4 are they going to be the LS7 ones now ???
Just a bit confused.
03-20-2010, 11:56 PM
#32
The way I understand it, each new generation of lifter replaces the preceding one, which means you can't go to the parts counter and order the LS1 lifters from '99, which makes sense, if over a generation of building engines, the GM engineers decide pushing up the cup in the new lifter will make the valvetrain quieter, run less of a risk for premature failure, etc...basically if you can tell me the new lifter is better in every way than the old one, then I'd have no reason to ask for the old part number.
As to the first part of your post, maybe it's one of those things that we're supposed to just accept and run with; I mean, if I bring my new truck in and a lifter gave out, they'd probably change both lifters and pushrods under warranty...and there probably wouldn't be enough people out of warranty up in arms about having to replace both lifters and pushrods to really influence GM's decision making.
It would also be nice to know what GM specifies for acceptable preload with these lifters; it's fine to hear "engine builder x likes to run y amount of preload", but maybe the LS7's have enough extra tolerance built into them that stock length pushrods won't create any undue stress on the valvetrain...just in this thread alone you'll read from more than one person saying preload is acceptable from .050 all the way past .100, so if GM did build these lifters to accept almost a tenth of an inch of variance, then stock pushrods could very well be fine in an otherwise stock application.
As to the first part of your post, maybe it's one of those things that we're supposed to just accept and run with; I mean, if I bring my new truck in and a lifter gave out, they'd probably change both lifters and pushrods under warranty...and there probably wouldn't be enough people out of warranty up in arms about having to replace both lifters and pushrods to really influence GM's decision making.
It would also be nice to know what GM specifies for acceptable preload with these lifters; it's fine to hear "engine builder x likes to run y amount of preload", but maybe the LS7's have enough extra tolerance built into them that stock length pushrods won't create any undue stress on the valvetrain...just in this thread alone you'll read from more than one person saying preload is acceptable from .050 all the way past .100, so if GM did build these lifters to accept almost a tenth of an inch of variance, then stock pushrods could very well be fine in an otherwise stock application.
03-21-2010, 06:42 AM
#34
The way I understand it, each new generation of lifter replaces the preceding one, which means you can't go to the parts counter and order the LS1 lifters from '99, which makes sense, if over a generation of building engines, the GM engineers decide pushing up the cup in the new lifter will make the valvetrain quieter, run less of a risk for premature failure, etc...basically if you can tell me the new lifter is better in every way than the old one, then I'd have no reason to ask for the old part number.
As to the first part of your post, maybe it's one of those things that we're supposed to just accept and run with; I mean, if I bring my new truck in and a lifter gave out, they'd probably change both lifters and pushrods under warranty...and there probably wouldn't be enough people out of warranty up in arms about having to replace both lifters and pushrods to really influence GM's decision making.
It would also be nice to know what GM specifies for acceptable preload with these lifters; it's fine to hear "engine builder x likes to run y amount of preload", but maybe the LS7's have enough extra tolerance built into them that stock length pushrods won't create any undue stress on the valvetrain...just in this thread alone you'll read from more than one person saying preload is acceptable from .050 all the way past .100, so if GM did build these lifters to accept almost a tenth of an inch of variance, then stock pushrods could very well be fine in an otherwise stock application.
As to the first part of your post, maybe it's one of those things that we're supposed to just accept and run with; I mean, if I bring my new truck in and a lifter gave out, they'd probably change both lifters and pushrods under warranty...and there probably wouldn't be enough people out of warranty up in arms about having to replace both lifters and pushrods to really influence GM's decision making.
It would also be nice to know what GM specifies for acceptable preload with these lifters; it's fine to hear "engine builder x likes to run y amount of preload", but maybe the LS7's have enough extra tolerance built into them that stock length pushrods won't create any undue stress on the valvetrain...just in this thread alone you'll read from more than one person saying preload is acceptable from .050 all the way past .100, so if GM did build these lifters to accept almost a tenth of an inch of variance, then stock pushrods could very well be fine in an otherwise stock application.
Appreciate your views in this thread!
03-21-2010, 05:58 PM
#37
I say may because I'm not sure if they're any different on vvt motors; I know on the AFM motors they're slightly different to house the collapsible lifters. For 32 dollars you could at least have them on hand when you're tearing into the motor and pull one of the stock trays to compare, worst case you don't need them and can just send them back.
04-01-2010, 01:48 AM
#38
Well I said I would post my results so here they are...
Using the Comp pushrod length checker (7702-1), which has a range of 6.800" to 7.800", I got 9.25 turns to zero lash. I did this a few times on different valves/rockers on each bank and got the same results. I could't lengthen the pushrod tool when it was in the block, so I slowly lengthened it and tightened down the rocker until it got to zero lash right when the bolt went snug. Each turn is 0.050" so...
6.800" + 9.25*0.050" = 7.2625"
I had the stock 7.38", Comp 7.375", and Comp 7.350" pushrods to choose from. I went with the 7.350" pushrods.
7.350" - 7.2625" = 0.0875" of preload.
This seemed like a good amount, more than most people say to target, but should be just fine. The 7.375" pushrods would have given me 0.1125" of preload which I think is too much.
This is on a '01 5.3L motor, LS7 lifters, stock unmilled 706 heads, stock block, Felpro 9292PT head gaskets (0.055" compressed from what I could find on this site).
Using the Comp pushrod length checker (7702-1), which has a range of 6.800" to 7.800", I got 9.25 turns to zero lash. I did this a few times on different valves/rockers on each bank and got the same results. I could't lengthen the pushrod tool when it was in the block, so I slowly lengthened it and tightened down the rocker until it got to zero lash right when the bolt went snug. Each turn is 0.050" so...
6.800" + 9.25*0.050" = 7.2625"
I had the stock 7.38", Comp 7.375", and Comp 7.350" pushrods to choose from. I went with the 7.350" pushrods.
7.350" - 7.2625" = 0.0875" of preload.
This seemed like a good amount, more than most people say to target, but should be just fine. The 7.375" pushrods would have given me 0.1125" of preload which I think is too much.
This is on a '01 5.3L motor, LS7 lifters, stock unmilled 706 heads, stock block, Felpro 9292PT head gaskets (0.055" compressed from what I could find on this site).
Last edited by Ferocity02; 04-01-2010 at 11:14 AM.
04-01-2010, 11:00 AM
#40
Thanks Ferocity02, that's good info 
Sounds like you hit it right on the head with your pre-load. .875 with a 7.35 pushrod will be fine. IIRC, I've read of guys running more pre-load than that without any noise or problems...although I like a little less, but you gotta go with the closest you can get with the parts available to you 
Sounds like you hit it right on the head with your pre-load. .875 with a 7.35 pushrod will be fine. IIRC, I've read of guys running more pre-load than that without any noise or problems...although I like a little less, but you gotta go with the closest you can get with the parts available to you
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