Unreal

He probably has the base 454. 8 bolt flywheel, not that great rods, not great pistons. Heavy, cam is not great for a high performance application. Decent motor if you have an old camaro and want to swap a motor in, but a mildly built LS7 will run circles around a crate 454.

Now if you pull the heads and get them worked, swap cams, etc etc you can do ok, but still can't do anything about the added 150+lbs, and cooling an iron block.

1fast97gsx

Mine is not the r version, mine is the one in the link I posted above. I have a FAST 102 intake manifold and Nick Williams throttle body on it. The car runs great overall and the power / torque feels awesome, I just want to clear up any worries I have by fixing all the minor issues. I pulled the valve covers last night to recheck rockers / valvesprings and everything seems to be ok. It almost sounds like a lifter type noise but it doesn't seem like it's bank specific. I'm going to try different oil and bleeding the lifters. Maybe I'm over thinking it / paranoid.

1fast97gsx

Who do you recommend to do the head work? I changed to a thicker oil and it didn't help at all. I'm thinking it might be a lifter at this point ... do heads need to be pulled to get lifters out?

Unreal

Maybe not, especially if you didn't touch it since the LSX has lifter windows. Can pop them out through the valley cover.

WCCH or AI is who I would use for head work. Find out if they have a program for those LSX as cast heads. Swap a new cam, MSD intake, etc. Still don't like the stroke, weight, etc but not much of a choice at this point.

Michael_D

Your initial post indicated it was the R version, and the link just goes to the Chevy website. That's why I asked.

I always get suspicious when I hear things like "They said they upgraded the springs"... The ticking you are hearing is mostly due to insufficient lifter pre load. Lifters don't bleed. If there's air entrained, it'll just have to work itself out over time. I'm kinda with Unreal on this... Not a big fan of your engine. But it's what you got, so might as well make the best of it.

1fast97gsx

Oh ok, I didn't realize the link wasn't good, I did it with my phone. Sorry, what are the chances a lifter spun in the bore or just jammed? Sorry not used to pushrod engines just yet. Just wondering if that's what caused the spring to break in the first place.

JoesC5

I believe the LSX454 with a stock LS7 intake produces 627BHp/586 lb-ft of torque. Not to shabby, but with a 6,500 RPM redline and stock exhaust manifolds.

It comes with 4340 forged steel crankshaft(stronger 8 bolt flange), 4340 forged steel rods, and forged aluminum 11.0:1 pistons. It does have a stronger cast iron block then the LS7. cam has .648I/.648E with 236*I/246*E. That's hotter than the stock LS7 cam. Heads are a stronger 6 bolt design vs the stock LS7 heads.

Yes, it weighs 123 pounds more than the aluminum LS7 block(230 pounds LSX CI bare block and 107 pounds LS7 Al bare block), but is more bullet proof than a otherwise stock LS7 with a hot cam that will produce 627 horsepower at the flywheel with a stock intake manifold and stock exhaust manifolds in place.

That extra weight is about the same as the additional weight on the front end of a ZR1 with it's supercharger, heat exchanger, etc, and the ZR1 is not handicapped by that extra weight on the front end. Actually, the Z06 with a LSX454 should weigh about 50 pounds less than a ZR1.

Michael_D

Very slim chance. These engines use a device to prevent lifter rotation. It's called a 'lifter tray', which doesn't sound like something that would do what it does.....

Springs breaking are usually the result of someone not installing them correctly, or using the wrong spring for lift. Modern valve springs just don't break without a something causing them to break.

If it were me, I'd plan to yank the heads and at minimum, visually inspect the cam lobes the best you can through the valley window. Then send those heads out to someone for additional port work. Don't get crazy with it. Just a wee bit o' love is all they need. DO NOT remove the intake port swirl damn (called a few different things).... Reeplace the lifters with some good Morel or Johnson, and install better springs and set them up correctly. PAC or PSI are my preferred springs.

The MSD intake manifold the newest thing right now. I'm not sold on it.

Didn't talk much about tuning. A bad tune can make an engine run hot.

Unreal

If a lifter spun the cam is trashed and it wouldn't run.

Any "advantages" like stronger block and 6 bolt heads are completely worthless on a Na <1000hp build.

1fast97gsx

Yea that was my whole reasoning for buying the car. About 100 hp more than a stock c6z with an engine that should be reliable / was made by GM. Apparently I should have just bought a zr1 lol

1fast97gsx

Thanks for the advice. Place that put the car together also tuned it but I will have it redone once issues are sorted out.

1fast97gsx

Update in case anyone was wondering ...

Pushrod was bent on the same cylinder that had the spring break. Also the rocker was coming apart / needle bearings were coming out. I'm not sure what was the original failure but cam looks ok so at this time I'm replacing the lifters, pushrods and springs.

The lifters DO come out without removing heads. The lifter trays are individual for each cylinder and there is enough room to get them out. Good piece of information for others!

C5 Hardtop

A bent push rod and broken spring. How could it fail in that way? Do you think the push rods are the correct length?

1fast97gsx

That was my thought too but they are the same for each cylinder and it's a crate engine so I don't know why they wouldn't be. Really weird and doesn't make 100% sense still. Lifter tray isn't broken ( they are plastic on 454 crate engines ) so I don't think the lifter somehow was popped up / jammed. Maybe just a failed spring and when the spring was broken the pushrod had play and maybe somehow jumped out of the lifter and jammed itself causing the bend and now the messed up rocker. Either way replacing lifter, push rod, rocker and spring has to fix it!

C5 Hardtop

That makes sense. Since you have it apart and it was a used car (anything could have been done to the engine), consider measuring the pushrods and compare that with what length they should be.

Michael_D

You have had a broke valve spring, and now you find a bent pushrod.....

This could be a chicken or the egg conundrum.

It's probably a ratio of about 9 out of 10 where broke valve springs are from coil bind. A bent pushrod is usually a result of piston to valve contact, or coil bind. The valve cannot be opened further in either situation, but the cam lobe is still forcing the rocker open. Something has to give.

If you have more than one broke spring and / or bent pushrods, then it's probably a set up problem. Spring installed did not have adequate distance to coil bind. When you see only one, then the cause becomes murky. I'd tend to think it was a single lifter. Something caused the lifter to pump up (or conversely, not drain down). I have seen a dislodged seal trapped between coils once, but nothing happened. I just found it like that during tear down.

In situations like this, I just resign myself to doing a complete tear down and go through the entire top end to make sure the single failure does not turn into subsequent failures. Start with the easy stuff first, like springs. Verify they are set up correctly. Find coil bind distance if not already known. Then I just start working my way down, into the engine. Sometimes I get lucky, and sometimes the engine comes out of the car.

cv67

There is nothing wrong with that engine, sure put a smaller one in!

A bent pushrod or spring esp with a higher lift cam can happen to any motor, comes with the territory.

Even though they are HR with rpm and lift comes higher risk/shorter life
They need to be checked once in awhile just like a SR would.

Noise could be the nature of the beast...or spring, retainer to guide, worn guide etc sometimes running one wiht the valvecover off it possible can narrow it down sound really travels around in an engine. Make sure everythings right best you can and run it most motors that make power have some type of noise.
If you heard mine youd think the valvetrain was coming apart.