TUFF LT1

The car will not fire with the rockers set to 1/8 1/4 past 0 lash and it seems to crank kind of hard. I just adjusted them again to 1/2 past 0 lash and it seemed to almost want to fire and it sounded much more normal cranking over. I'm thinking about trying 3/4 past 0 lash next. Does this sound like a reasonable idea? Also will 3/4 damage anything? By the way this is with comp 987 double springs, comp r lifters and comp pro mag 1.6 rr. Thanks for your help!

TUFF LT1

that is at 1/8 or 1/4...sorry

LilJayV10

Are you letting the engine warm up before you try to adjust them? I normally go 1/2 turn, anymore than that and I feel its to much preload. GM calls for 3/4-1 turn, thats ridiculous if you ask me. I adjust alot of rockers and for me atleast, 1/2 turn is the best. If you get them to tight, it will start popping out of the exhaust and throttle body.

jonaddis84

Reason it probably sounds easier cranking is your losing compression from hanging valves. If you dont even adjust them, just set to 0 lash, the car will run, just not safely.

You have other problems.

TUFF LT1

At 1/8 and 1/4 turn the car almost wanted to backfire when it was cranking. at 1/2 the car cranked almost like normal though.

TUFF LT1

I tried seting them to 0 lash and starting it but it wouldn't fire at 0 lash either??? It started the very first time that I adjusted them but I turned the engine off because I thought that the rockers were way to loose. Maybe I was wrong about that now that I look back. I have good fuel and spark?

LilJayV10

Another thing is once you adjust them, you should drive it or let it run for a while and let the lifters "calm" down some. Some people might think this is funny but its true. After the lifters get adjusted, then pump up, and some times over pump(when the oil pressure won't bleed off) they act strange. Driving it lets the valvetrain "settle" and after it does i'd recheck them. You ever notice how you adjust the rockers and a day or so later one bastard rocker arm starts ticking? It's because everything has settled and there's just a little more clearence. Yes it can also be from a rocker nut lossing too, but if thats the case, the rocker will get louder and louder.

jonaddis84

Is this right after a cam install? If so make sure you pull the pcm fuse for a few seconds, and you will need to "keep" the engine running for a minute with the throttle so the pcm can "learn". Put the rockers at 1/4 (IMO) and try that, the rocker adjustment, as long as it isnt too FAR, isnt going to keep the car from running.

TUFF LT1

The first time that I tried to start the engine after the rocker install it started like I said but I only let it run for about 10 sec or so.

jonaddis84

Im lost...try this...like i said set them to 1/4 turn..OK?

Reset the PCM...

Start the car...

Dont worry about ticking theyll do that, rockers are loud...

keep the car running with the throttle if it wants to die

TUFF LT1

Yes it is after a cam install. So pull the pcm fuse? Why did the car start up the very first time that I tried to start It?? That's something I will have to try though...I'm at my whits end here.

TUFF LT1

Ok sounds good I think that the car start if I give it some gas. but it will run really choppy? Will that hurt anything?

jonaddis84

for example..
just did an xe224/230 install with rockers, lifters, etc on a buddies car

started it like 5 times and it died

pulled the pcm, started it, still died

started it and kept it running via throttle, ran it for a few minutes, and then it idled fine.

FI pcms need a little time to get used to the new parts

jonaddis84

nope...assuming everything has been installed correctly

TUFF LT1

Thanks for all of your help jonaddis84! I'll go try that. But will I hurt anything by keeping it running with the throttle if it sounds like it really wants to die?