Ls7 lifters on an lt1
 

As preventative maintenance after warranty is up and for small cam applications, would gm performance ls7 #12499225 lifters work on a stock lt1 without changing anything else out?

Maybe new push rods if the length is a little different. Initial research says they might be .5 shorter so might need slightly longer push rods.

Have a guy selling some gm performance lifters for cheap in the box new as he recently sold his z28. I've been under the impression that they would work just fine also but want to make sure. Part number 88958689.

Yes they will work but you need Head gaskets, head bolts, valve cover gaskets intake gaskets, exhaust gaskets valley plate gasket and lifter buckets for the install and about 16 hours of labor.

Your better off doing a complete cam package all at once for the amount of work to change out just the lifters.

Thanks for the advice.

They do not work on AFM lobe.

Even small lift aftermarket cams have faster lift ramps, so it is not only peak lift. I would assume ls7 lifters would work on a gm hot cam. Cam Motion is known for a mild ramp.

Fast ramps = power, I went with a .592 lift custom grind cam motion and Johnston lifters, I’ll change valve springs every 40k miles. I run Texas speed dual .660 springs because I believe boost, rpm and valve bounce actually failed my ls7 lifter on a steep lift cam. So my fix is a stiff spring, lower lift, and a strong lifter.

Good information...thanks.

I myself have not run the LS7 lifters, but have seen so many people with issues I decided to go with Johnson 2110s in my build.

As my tuner described it - “the LS7 lifter is just fine for the application it was designed for, sub-600” lift cams under 7000rpm. That is the application in which they were designed & warrantied at and are not designed to do anything beyond that”. The factory LS7 cam is only .590 lift just FYI

This is not the area to save money on a build - best case scenario if you loose a lifter it will need torn down to at least the cam, however more than likely you will pump a bunch of metal thru the bearings when the rollers fail (this is the thing that is common on the LS7 lifter, the roller seizes on the axle and it grinds the cam up).

The Johnson LinkBar Short Travel (2116LSR) is what GM uses on the COPO engine, you can get a 2110 which is their standard travel lifter but is still considered a low leak down lifter vs the GM lifters. They do make their own short travel version called a 2110R, or you can get into linked style to getaway from the trays all together with 2116L or the Race Versions of 2116LSR.

I see a lot of people spend a lot of money on super chargers, meth systems, strokers, etc.... and put in the $125 lifter and 5/16” pushrods. If you look on CorvetteForum there are a lot of failures, the Johnson lifters are the ones they end up going to on the next build

The other stuff isn't really applicable towards my inquiry since I wouldn't be boosting, spinning above 7k, or getting a high lift cam above .600.... but is it confirmed that they wouldn't work with the stock cam with afm lobes?

Ive always consindered the johnson lifters if i was to do a heads cam car, i was considering the ls7 lifters for something small like you mentioned. A baby cam spinning at 7k or less.

Now I do wonder how the gm performance 88958689 lifters compare as supposedly they are rated for high rpm applications.

Thanks for the insight btw.

I could NOT get them to work and I personally tried, The AFM lobe has a special ramp profile that prevents the LS7 lifter from leaking down. So there is a issue with the valves closing due to lifter overfill. This is my thinking after trying. I have access to all different lengths of pushrods. Others may know more; I raced a Challenger before this so no beforehand knowledge on AFM.

Once again it is lift, ramp speed, and RPM that cause most failures. My specific failure added in boost and stiff springs leading to what I think was valve bounce. Ramp speed is The number 1 issue that fails the ls7 lifter for most failure IMO, hence I’d spec it only for the GM hot cam. I’d talk to Cam Motion to see if they rec the LS7 on their small sub .600 lift cam.

GM ramp speed is low so it is not an RPM issue in regards to failure, I’d assume it s more of bleed down valving.

Since it is ramp speed as the biggest problem, I’d thinK GM hot or Cam Motion would be ok to 100k. Both have under .595 lift and Cam motion will bring any lift you want. Their off the shelf stuff gets pretty high after the first tw grinds

Yeah and as u likely know but I’ll lay it out here, it’s not only a function of lift in a given duration. How it gets to the lift makes a huge difference as well.

I’d like to know how much heavier these lt1 valves are over ls1 and ls6 valves

yep:thumbup:

Looks like the LS6 intake is hollow cause it is heck of light:

https://ls1tech.com/forums/generatio...e-results.html


Let me do a memory dump on valve springs I would assume the LT1 spring similar to yellow or blue gm springs ( 90 seat, 295 open at .550). Cam Motion has a upto to .625 lift 1.8 install has a pretty mild beehive that should work. PAC spring would be good, lastly BTR has several kits out now including a conical kit:

https://www.briantooleyracing.com/va...4-engines.html
also BTR beehive:
https://www.briantooleyracing.com/bt...pring-kit.html
If it were me and an AFM cam, I'd probably go with the above and shim to 1.850 install so about 117 lbs seat and dunno too lazy to get a calculator but say 330 lbs open on the AFM cam's .576 lift (Lingenfelter GT30). For the smallest cam motion .596" (DOD delete) I'd probably do the recommended install height.
The only caution I can think of is it looks like the kits come with a .070 seat, You may have to keep the factory thin seat and shim (or not) from there.

I went with a TSP .660 dual spring that has a special seat / valve seal, as it was the spec for my original cam. I'm completely sold on the conical, but it was just coming out when I did my first cam years ago now. Even though my cam is way smaller in lift now with a gentle ramp, the Manley valve is soild (slight undercut head for flow). So that is a lot heavier valve to close. I almost went with LT4 titanium intake... cool and light and solid.

Cam Motion beehive:
http://www.cammotion.com/valve-train...ve-spring-set/

Sorry, I have forgotten the LT1 stock install height vs the Texas Speed with their spring seat, you all have to do your own search.

The tricky part to my mind is that even dual springs have oscillation that there is near zero spring pressure and you want to run the least spring that will not allow valve float / bounce, and least can mean upto 40K miles when you change them out. Hence personally am sold on conical, I just don't know the seat and spring rate on the BTR conical.

Superchevy did their install with a much stiffer (assumed) concial vs the BTR on a AFM cam:
http://www.superchevy.com/how-to/eng...-lt1-cam-swap/
I don't know the longevity on this even with really mild ramps. The dyno is gone but I believe the cam pulled to 7200 RPM.Here I found the quote " The springs we’ll be using (PN 7228-16) have a spring rate of 438 lb/inch, a seat load of 136 pounds at 1.800 inches, and an open load of 412 at 1.170 inches. Comp’s own testing of these springs has shown better valve control for more power over the traditional beehive and cylindrical springs."

Hence my thinking of say 117 seat and 295 open for a mild cam. As a complete and total guess (already noted at the begging), I'd say the stock spring is 98 seat and at .551 dunno 300 lbs open. But I don't know, and it could be the AFM requires an even weaker open spring and that is why the LT4 intake is titanium (weight) and LT1 intake is hollow (weight). I would not be surprised at a sub 300 open spec at a low .551 lift.

Put it in perspective superchevy did a 136 seat puls .572 (comp cam) x 438 = 386 lbs open on the conical. Yes I know that these stiff springs will have much less open pressure due to the relatively low lift. I just wonder on the ability of the AFM lifter to open this.

Just to finish this up Comp Cams Card calls for their 26918 beehive whith 125 seat and 372 ft-in would yield 329 pounds open at .572. Humm not too bad, so it would lend some credence to some people saying that the comp cams, especially the smaller AFM can run factory stock springs, slightly more lift would bring slightly more open pressure with the factory spring. I don't have a spring scale handy or I'd give you all the specs. The beehive are cheap, I'd run a better Pac spring, I'm just giving you all what the mfgs are saying. PAC weakest spring may actually work (need to wait for infor on the stock LT1 spring)

As a last reference point the LS7 lifter is designed to work with a 101 seat spring 310 lbs open, just remember the OEM cams have a very gradual acceleration and deceleration ramp and in this case it would be the gradual deceleration ramp that allows a relatively weak spring. 310 folks!!!!

Anybody know what spring is on the hotcam (DOD delete). I found this:
https://sdparts.com/i-24080674-chevr...1-hot-cam.html so it says the stock 12678635 springs works with .570 lift cams this again lends credence to Comp Cam smaller AFM cams and lower RPM redlines can use the stock spring. I think the hot cam rec speed is 6800 RPM. I have to think yep, but the DOD delete Hotcam has really gentle ramps so they can get away with it. Note GM even says don't change the pushrod or the spring ain't gonna work (assume due to additional weight) so that is how close they are cutting it. i.e. stock spring is good at .570 lift and 6800 RPM with NO additional weight... Maybe just musing, the future holds lightweight 5/16 .075 thinwall molly pushrods and tool steel valve spring retainers, titanium intake valves and stock springs as the way to run AFM cams. i.e. can't increase spring pressure so one needs to cut down on weight.


I'm sorry probably should have broken this down to low lift AFM cams vs low lift DOD delete cams... my bad

What's the difference between LS7 lifters and the non-AFM GEN5 LT1 lifters?

I still am annoyed GM couldn't name the GEN5's something other than LT. It gets confusing, and you have to often distinguished between the motors.