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I order some Delphi LS7 lifters, Comp 1.5 roller tip rockers and BTR 7.200 pushrods. I just realized in the LS world, the rocker is torqued to 22ft and not a desired amount of "turn" like the SBC is so I guess I screwed up. Does anyone know how to set pre-load on this style lifter in an L98?
Typically those lifters want around .070 - .100" or so. Total travel is about .150", and you want half, plus a bit more to make up for wear over some period of time.
In LS motors, you don't "torque the lifters"; you just tighten the rocker bolts down to the standard torque for that hardware size (8mm), which is actually 30 N-m. That converts to about 21.7 ft-lbs if memory serves. It doesn't really matter all that much though; since the entire system that you're tightening is metal-to-metal, i.e. there's nothing that compresses, bends, stretches, or otherwise deforms, then all you really need is to get them "tight enough" (that they won't fall apart) but not "too tight" (strip threads, break bolts, etc.) It's not as though the whole system is going to behave the slightest bit differently depending on small variations in that torque.
Anyway, with 1.5 ratio SBC rockers and 24 thread per inch nuts, to get .080" of preload on the lifter, you need about .08" ÷ (1 ÷ 24 × (2.5 ÷ 1.5)) turns; or, a bit over 1 full turn. Call it 1-1/8 turn. Anything from 1 to 1¼ would be appropriate.
I'd be more concerned about how you came up with that length of push rod; since in the SBC, the ideal push rod length is whatever results in the minimum-width wipe pattern of the rocker tip across the valve stem tip. No way to know, really, until the whole system is assembled and spun a few times to make a witness mark.
Typically those lifters want around .070 - .100" or so. Total travel is about .150", and you want half, plus a bit more to make up for wear over some period of time.
In LS motors, you don't "torque the lifters"; you just tighten the rocker bolts down to the standard torque for that hardware size (8mm), which is actually 30 N-m. That converts to about 21.7 ft-lbs if memory serves. It doesn't really matter all that much though; since the entire system that you're tightening is metal-to-metal, i.e. there's nothing that compresses, bends, stretches, or otherwise deforms, then all you really need is to get them "tight enough" (that they won't fall apart) but not "too tight" (strip threads, break bolts, etc.) It's not as though the whole system is going to behave the slightest bit differently depending on small variations in that torque.
Anyway, with 1.5 ratio SBC rockers and 24 thread per inch nuts, to get .080" of preload on the lifter, you need about .08" ÷ (1 ÷ 24 × (2.5 ÷ 1.5)) turns; or, a bit over 1 full turn. Call it 1-1/8 turn. Anything from 1 to 1¼ would be appropriate.
I'd be more concerned about how you came up with that length of push rod; since in the SBC, the ideal push rod length is whatever results in the minimum-width wipe pattern of the rocker tip across the valve stem tip. No way to know, really, until the whole system is assembled and spun a few times to make a witness mark.
Thank you so much! This is all above my head. I read and came up with the stock pushrods being 7.200 from several threads going back some years. I think I asked Summit Racing as well. Now you have ME worried that I got it wrong.
You must measure for proper pushrod length but luckily the LS7 lifters have a pretty wide pre load range (as mentioned above). As such you can get away with pushrods that are not perfect down to the thousandth that you may come up in your measurement. This will help you avoid having multiple custom lengths and instead find some sized already off the catalog.
I am about to pull the garbage LS7s out of my L31 based 383 and put a Lunati 72910-16 lifter set in its place. Lloyd Elliot told me many of his customers have been using them the past few years with good results. The quietest the LS7s have been is with 0.083" preload that calculates out to 1-1/4 turn with a 1.6 rocker. The GMPP LS7 lifter set I have is from ~10 years ago, but they are louder than the Rhoads V-Max lifters I pulled out of the engine to put the LS7s in. My fuel economy tanked after pulling the Rhoads lifters out, from 20+ MPG to a best of 16 mpg. I have a custom spec'd Erson cam to go in place of the current Comp cam when the Lunati lifters go in as well. The Comp cam is a 218/228 on a 108 LSA and the Erson cam is a 218/218 on a 112 LSA.
This is with LS7s at 0.083" preload. The lifters go from nice and quiet to clacking pretty noticeably when the throttle is bumped and released.
The original GM "LS7" lifters were the updated replacement for all LSx lifters that had gone before. Even more convenient, they're the same, dimensionally, as factory-roller SBC lifters. Direct drop-in.
Unfortunately, there are now ANY NUMBER of poorly made copies running around. Especially since GM, and the various mfrs that ACTUALLY MAKE them, can't crank em out fast enough to meet demand.
So if you go to any web site that allows "independent" sellers, they peddle all sorts of chinesium CRAP and call it "LS7". Some no doubt are perfectly fine. Some, maybe not. Who knows. The virtues of ethically challenged govt-owned predatory capitalism at its finest. Prosit vendor, caveat emptor.
As far as "noisy", there are LOTS of things about lifters that can cause that. Anything from piddle valves that leeeeeek, to rollers that aren't round, to bearings that aren't... yeah, to loose tolerances in the bores, to ... the list just goes on. Lifters being a "reciprocating" part, there are SO MANY WAYS they can make noise, it boggles the mind. Most have to do with excessive tolerances somewhere. So, just do the math.
Given that there are only a finite number of lifter mfrs in existence, and that cam companies such as Comp Crane GMPP Lunati TSP Cammotion BTR etc. don't "make" them but only can draw on, I doubt VERY SERIOUSLY that the name on the box is any kind of guarantee of ANYTHING. In 2023, ya lays yer money down, ya takes yer chances.
Last edited by sofakingdom; 10-10-2023 at 08:57 PM.
The original GM "LS7" lifters were the updated replacement for all LSx lifters that had gone before. Even more convenient, they're the same, dimensionally, as factory-roller SBC lifters. Direct drop-in.
Unfortunately, there are now ANY NUMBER of poorly made copies running around. Especially since GM, and the various mfrs that ACTUALLY MAKE them, can't crank em out fast enough to meet demand.
So if you go to any web site that allows "independent" sellers, they peddle all sorts of chinesium CRAP and call it "LS7". Some no doubt are perfectly fine. Some, maybe not. Who knows. The virtues of ethically challenged govt-owned predatory capitalism at its finest. Prosit vendor, caveat emptor.
As far as "noisy", there are LOTS of things about lifters that can cause that. Anything from piddle valves that leeeeeek, to rollers that aren't round, to bearings that aren't... yeah, to loose tolerances in the bores, to ... the list just goes on. Lifters being a "reciprocating" part, there are SO MANY WAYS they can make noise, it boggles the mind. Most have to do with excessive tolerances somewhere. So, just do the math.
Given that there are only a finite number of lifter mfrs in existence, and that cam companies such as Comp Crane GMPP Lunati TSP Cammotion BTR etc. don't "make" them but only can draw on, I doubt VERY SERIOUSLY that the name on the box is any kind of guarantee of ANYTHING. In 2023, ya lays yer money down, ya takes yer chances.
Yea getting good lifters now is like playing Russian Roulette with Dirty Harry's favorite side arm. That is why I am hoping Lloyd Elliot steered me to a lifter brand that currently works well in 2023. All he has to go off of is what lifter is working for his customers. I will not know the answer to that until my engine gets partially torn down and the cam/lifters replaced.
Seems the forums blew up with lifter failures after LS engine went out of regular production. I think the OEM manufacturer exited the business when the production volumes declined, and the parts are now coming from lower tier aftermarket suppliers. I wouldn't use a GM lifter for anything these days. Johnson make a quality drop-in lifter, and there are other American companies with vast experience.
Seems the forums blew up with lifter failures after LS engine went out of regular production. I think the OEM manufacturer exited the business when the production volumes declined, and the parts are now coming from lower tier aftermarket suppliers. I wouldn't use a GM lifter for anything these days. Johnson make a quality drop-in lifter, and there are other American companies with vast experience.
The same lifters are basically still in new GM engines and they are failing left and right. GM was still making the GenIV engines when I bought the set of LS7s I used in the 383 back in 2013ish.
Johnson make a quality drop-in lifter, and there are other American companies with vast experience.
Johnson lifters are very well made, and don't appear to be outsourced. I am running their short travel tie bar lifters and they are extremely well made. Their drop in lifters would be my go to for your traditional style lifter needs.
I've got a brand new set of Johnson 2116 tie-bars but those are waiting for a sweet LS build when I find an LC9 motor. I'm HOPING these Delphi will be ok in a low RPM L98 with only headers. I'm wanting to LS swap this car next fall
I order some Delphi LS7 lifters, Comp 1.5 roller tip rockers and BTR 7.200 pushrods. I just realized in the LS world, the rocker is torqued to 22ft and not a desired amount of "turn" like the SBC is so I guess I screwed up. Does anyone know how to set pre-load on this style lifter in an L98?
I am more than happy to help! Total coincidence how I found this lol I was actually on the looking of airbag codes but anyway…i just replaced my L98 lifters with LS7 lifters to mine as well. So you’ll tighten the rocker nut to “zero flash”. then “one” full turn +/- a 1/4. One full turn is all you’ll need. Those numbers come from the GM manual that I have for my 91 camaro. Those numbers applies to all L98 factory roller motors. Also keep in mind that the cup/plunger on an LS7 lifter a lot higher versus an L98 cup/plunger so you’ll need much shorter push rods. I have a push rod length checker by Pro Form Part# 66789. It’s for the factory 3/8–24 rocker stud. (They also make it for the 7/16 rocker stud as well) So I also decided to use that tool to check the factory geometry and found that the factory push rods were in fact too long on a complete factory set up. Here are some pictures to show you… hope this helps if you have any other questions feel free to email me directly or shoot me a text jman84884@yahoo.com (401) 439-5300 So clearly, you cannot just use the LS7 lifter with the factory push rod and factory rockers. Your rocker is going to be pushing off your valve. And this is what it looks like if you do…. Here is the correct length push rod. This is an adjustable push rod tool to get the exact length needed. Stock L98 push rod is 7 3/16” or 7.1875” long
I am more than happy to help! Total coincidence how I found this lol I was actually on the looking of airbag codes but anyway…i just replaced my L98 lifters with LS7 lifters to mine as well. So you’ll tighten the rocker nut to “zero flash”. then “one” full turn +/- a 1/4. One full turn is all you’ll need. Those numbers come from the GM manual that I have for my 91 camaro. Those numbers applies to all L98 factory roller motors. Also keep in mind that the cup/plunger on an LS7 lifter a lot higher versus an L98 cup/plunger so you’ll need much shorter push rods. I have a push rod length checker by Pro Form Part# 66789. It’s for the factory 3/8–24 rocker stud. (They also make it for the 7/16 rocker stud as well) So I also decided to use that tool to check the factory geometry and found that the factory push rods were in fact too long on a complete factory set up. Here are some pictures to show you… hope this helps if you have any other questions feel free to email me directly or shoot me a text jman84884@yahoo.com (401) 439-5300 So clearly, you cannot just use the LS7 lifter with the factory push rod and factory rockers. Your rocker is going to be pushing off your valve. And this is what it looks like if you do…. Here is the correct length push rod. This is an adjustable push rod tool to get the exact length needed. Stock L98 push rod is 7 3/16” or 7.1875” long
Something else is wrong with your setup. The LS7 lifters have the same dimension from the roller wheel to the pushrod cup as the earlier lifters. The lifter design was on of the small block carryover items in the early LS1. GM then superceeded the lifters to the newer design.
Something else is wrong with your setup. The LS7 lifters have the same dimension from the roller wheel to the pushrod cup as the earlier lifters. The lifter design was on of the small block carryover items in the early LS1. GM then superceeded the lifters to the newer design.
I don’t know what to tell you, the proof is in the pudding🤷🏻♀️ I’m not making this stuff up hence why I sent photos of proof. It’s a brand new rebuilt stock 350 TPI with the original components except for the bearings obviously and the lifters🤷🏻♀️
I don’t know what to tell you, the proof is in the pudding🤷🏻♀️ I’m not making this stuff up hence why I sent photos of proof. It’s a brand new rebuilt stock 350 TPI with the original components except for the bearings obviously and the lifters🤷🏻♀️
Like I said something changed and that is why it is good to check this stuff. I have run the LS7 lifters in both LT1s and L31s that required stock pushrods when I checked the geometry. Are you sure your lifter was on the base circle of the cam when you checked? My 383 needed a longer than stock pushrod because it has 0.100" longer valves in it as well as both the block deck and heads were milled down. In my 383 I had to shim the distributor body and shaft as well. Not an uncommon problem, but I do not understand it given you have stock rocker arms.
I will also add I have that same checker and it does not preload the lifter. So you have to add the 0.080" preload to the pushrod length. When you preload the lifter the geometry changes.
I will also add that the GM production LS7s ran 0.130" lifter preload. I had a stock one apart and checked it as I was pulling it apart. I put tie bar, short travel lifters and adjustable rockers on that engine since the cam we put in it was expected to make peak HP at 7,200.
I have run LS7s preloaded between 0.060" and 0.130" with little difference in noise. The preload actually changes the cam specs a bit. Less preload makes the cam act smaller, more preload makes it act larger. Richard Holdener found the same results in his LS pushrod length dyno tests. Since the LS he tested does not use an adjustable valvetrain, his pushrod length changes directly altered lifter preload. For a performance engine you want more preload with a LS7 lifter. For something that just needs to run down the road, I would run right around 0.080", 1-1/4 turn is 0.083" with the 1.6 rocker in my engine. It idles a little smoother, has a bit more low-speed torque and is a bit quieter than running at 0.130".
10-10-2023, 11:26 AM
