So, before you flame me, I have read quite a bit and am more confused then ever. I’m rebuilding a 96 LT1, and bought these lifters.... CHEAP. Are these the correct ones for my application? I was pretty sure they are, but, I would like some other opinions. Thanks🤙

 

Don’t know but 92-95 list a ACD# HL112 and 96-97 list ACD# HL123.

 

Seems to be a cheaper "LS7" lifter
https://ls1tech.com/forums/generatio...7122490-a.html

I would stay away.

 

Cheap and valvetrain should never be in the same sentence as an advantage. Never skimp on the valvetrain. I'd also stay away from LS7 lifters.

 

I thought the LS7 lifters were the way to go?

 

Cheap as in, a buddy had them for a project long gone and I didn’t pay much, so, not a loss if not used. And yes, I thought they were the way to go as well, and there-in lies the reason for my initial post and my confusion, lol

 

I do not think their the "LS7" lifters people refer to, they are the cheaper knock off equivalaents to LS7s.

Either way. cheap lifters are not a good plan.

 

My understanding is that the LS7 lifter supercedes it's predecessors? His are AC Delco so not seeing how there would be an issue unless that's a known crap PN.

 

That was my thought, they are an AC Delco part, I wouldn’t think they would be “ cheap”

 

Not everything AC Delco today is the AC Delco of the past unfortunately.

 

From the thread I linked above,

I trashed a set of LS7 lifters in my motor, and a friend's motor could never get them to quiet down. If you have the money, get better lifters.

 

I had a set of LS7 lifters trash my engine. Some of the roller surfaces delaminated and wiped out the cam, which wiped out a lot of other things. I posted pictures on here a while ago. These were GM lifters. Loads of people say that the LS lifters are fine for an LT and maybe they are. It has been my own personal experience that they are not. Looking at them, you can also see that they are structurally different from the LTs. Most notably is the lifter cup itself is lower in the lifter body.

The correct LT lifter is GM part # 17120735 or AC Delco HL123

 

FWIW I have had Comp 850 lifters in for many years and miles now without issue in my 383. YMMV

agree "cheap" and valve train will almost always = BOOM

 

1. These are NOT LS7 lifters.

2. These are a 'universal' replacement GM lifter for mid-1980's small blocks all the way to the LS engine family.

3. They will work in the LT1.

KW

 

I guess I asked a pretty good question, huh, lol? And again, when I said “cheap”, I was referring to the fact that I paid very little for the lifters, not an indictment on its quality.

 

1) Hardly any manufacturer publishes important specs on their lifters, takes considerable effort to find: critically, lifter travel & cup height. (Crower calls it seat height)
2) Most people, without knowing any better, go "1/2 turn" or "3/4 turn" past zero lash. That's unacceptable to blindly set lash without knowing #1.

Math: 7/16" rocker stud does 20 threads/in. so 1/2 turn = .025" preload. 3/8" rocker stud does 24 threads/in. so 1/2 turn = .020833" preload.
Fact: LS7 lifter wants .060" - .120" preload with .080" - .100" ideal. On a 3/8" stud that's 2 full turns to get to/ just past .080" (.08333"). 1 1/2 turns to get to minimum advised spec of .060" minimum lash. On a 7/16" stud it's 1 1/4 to 1 1/2 turns.
Fact: Original LT1 lifter, the 17122490 and the 12499225 have the same cup height. That's why the 12499225 "LS7" lifter superseded the original LS1 lifter 17122490. If you want to use a "LS7" lifter, plan to add .060" - .080" to your pushrod after length checking it.

Aftermarket like Comp 850-16 and the short travel 875-15 and overpriced 15875-16 are yet again different from anything GM made. The 875s (running a set in my LT1) have very very little plunger travel and are limited to 1/8-1/4 turn on a 7/16" stud. 850s I can't find a spec online for travel but the cup height is the same as others above. A call to Comp may get you the specs on those. Seat/ cup height will be higher on retrofit hydraulic roller lifters with link bars (not applicable to any '87-up Gen 1 or Gen 2 SBC) and require shorter pushrods than traditional PRs on a pre-roller era block.

Disclaimer- I'm running "LS7" lifters in my truck (638 roller block based with hyd.roller cam. .075" preload on BTR PR7275312-16 pushrods (7.275"). Just a hair past 1 3/4 turns. on 3/8" ARP 134-7104 studs.

 

By eye, the cup height is different in an LT vs an LS, but you said "Original LT1 lifter, the 17122490 and the 12499225 have the same cup height." . You can easily see the difference. Am I looking at something different?

You stated that you need to add ".060" - .080" to your pushrod after length checking it" if using an LS lifter, so to me - that would mean they have different cup heights.

I am not trying to start ****. Just trying to understand. I appreciate the info you've shared above. It may account for the rollers delaminating in my engine as it would appear I was not running nearly enough pre-load.

 

Sorry for not being more clear. You add back the preload to the pushrod length since you're setting the lash to put the lifter plunger in the appropriate range of its travel spec. Different lifters require different amounts because the range of plunger travel varies per application/ design. Most 'race' lifters only take as little as .008" to maybe as much as .020". The "LS7" range is .060" - .120". For any HR lifter, too light and you lose lash and skate the rollers over the lobes and maybe eject a pushrod from its cup or the rocker arm, at minimum it's going to be noisy. Too heavy and it bottoms out and acts like a solid lifter and puts excessive strain on the valvetrain, usually with collapsed plunger springs and bent pushrods as the outcome, occasionally will break a rocker. "LS7" lifters have a broad range of travel for a lot of cushion in what Chevrolet would consider a 'performance' application (505HP Corvette). Hence the greater preload requirement, compared to the original HR SBC, LT1 and LS1 lifters (165-220HP, 275-305HP, 335HP respectively). What might be appropriate preload on one of these earlier lifters is way too light for an "LS7" lifter. Good lifter for the most part but you have to understand its design and use it appropriately. Would I use one in an HR application of my own over 475HP? Probably not. For anything beyond 450FWHP above 6200, I'd look to Crower or Jones.

Cup height should be measured relative to the bottom of the roller's centerline, where it makes contact with the lobe base circle. The body of the lifter may appear taller or shorter between roller and top rim, but the standard diameter of .842" is uniform unless the bores are expanded to use a larger body Ford (.874") or Mopar (.903") lifter. The oil holes are also standard distance above the roller's bottom centerline so they align properly with the lifter oil gallery, regardless of overall height of the lifter. The upper rim of the lifter may be taller or shorter, relative to the cup seat but that doesn't make the distance from the bottom of the roller to the seat any greater or lesser. What's inside (the amount and range of plunger movement) is the difference.

The "add .060" - .080" to your pushrod length after checking it" is specific to the "LS7" lifter. Finding the appropriate preload for the others isn't easy, but you really shouldn't use a lifter without knowing how to preload it, based on its internal specs. You can use a dry one to measure how far the plunger spring compresses from its resting position to get a pretty good idea though.