I blew a head gasket and took the engine apart, cleaned everything, and had the heads machines by a local shop. I put in new valvle stem seals, head gaskets, timing chain (w/ gasket and sprockets), intake gasket, new plugs, and valve cover gaskets.

After getting everything back together, it runs horribly. I can barely to get it to start if I give it part throttle when cranking. It dies immediately on idle and seems to be missing. Almost like the timing is way off. My laptop shows the vacuum is really low (MAP around 80-90 kPa) and it seems to be running very rich. I've tried putting the dist. 180 degrees off just to see if i put it in backwards and it runs just as good/bad. If I move it forward or backward one tooth, it refuses to show even any hints of starting. I've tried slowly rotating the dist. while a friend held the throttle open just enough to keep it running and couldn't find a spot where it would run right.

I thought I had an intake leak so I took it off, got new gaskets and used high-tack gasket sealer to hold the gaskets in place during reassembly.

I'm fairly certain the timing chain was installed properly. I followed the GM manual for everything and lined up the dots on the sprockets so they touched before taking the old chain and sprocket off. The dots were still lined up with the new chain and sprcokets installed as well.

I could really use some tips because the engine has been apart for 4 weeks and my temp plates are about to expire. I need to get the car e-checked in order to get new plates.

It's a '92 Camaro RS w/ a LO3 305 TBI

Thanks in advance

 

The first, and simplest thing I could imaging is that you forgot to hook up a vacuum line, or somehow punctured one. Refer to a Haynes manual, or look up the vacuum routing for a TBI. I have a diagram for a TPI but that won't help you much.

Since it runs as bad as you say, and it's really rich, I would assume that there is a problem with a line going to your MAP sensor, which is what tells your computer how much fuel to use based on how much air is getting in. Supposing it is a vacuum line at the MAP sensor, your computer thinks there is no air, and therefore will add more fuel to adjust (this is your rich condition) and it is causing crappy operation.


Just a shot in the dark, but it is where I would start.

 

I would also look at going back through the valves again to make sure none are too tight. That will cause MAP to go nuts, bad running(to the point of firing back out the tbi) and most of the things you described. It's a long shot but I'd adjust each valve static with the other valve full open. A good way to find zero lash is to turn the pushrod slowly with one hand while you tighten the valve lash with the other. When it stops spinning the first time you've reached a zero lash point. Tighten it maybe a 1/4 turn to 1/2 turn from there and see if it helps. This won't work on late model heads that tighten to torque. Only adjustables. Hope it helps a bit and good luck.

 

This might be my problem........ I followed the instructions for a '90 Firebird with the same engine... It said to tighten until the pushrod wouldn't spin, and then turn the nut one full turn. It has been backfiring out the TBI too

Would a '92 be different? How do I know if I'm supposed to tighten to a torque setting? Hopefully i didn't bend the crap out of my pushrods.

I'm not sure what you mean when you say to tighten each valve static.

why must the valve covers be so hard to get on and off

 

If you tighten it until the pushrod won't spin, you usually end up completely collapsing the lifter, and then the additional turn opens the valve.

If you're going to use that method, you want to do it until you the pushrod gets just slightly more difficult to turn.

 

I didn't think about someone who hasn't done a bunch of this kind of stuff but you're right about that. When you first start to adjust the valves(static=not running) you want to tighten the rocker until you feel a tad of resistence on it and THEN go another 1/4 to 1/2 turn further. I think a full turn is more than the hydraulics in the lifter are able to adjust for and will make the valve too tight in may cases. I'd rather have it a little loose and have to adjust it running than too tight and have the problems you're having right now. Good luck with it, Bill

 

bygblok has this right. I turn down on the adjustment nut until I can feel a tad of resistance to free turning the pushrod, you are now at zero lash. Then I turn down on the nut 1/4 turn, done. Of course you got to do this in the corect order, same as the firing order, one cylinder at a time.

But besides that, I would check all connections and vacuum lines, static timing, etc. What about the timing? If this is not done correctly, the engine will run like crap.

 

I had never adjusted lash before so i just followed what the GM manual said. If I can get my valve covers off without too much of a battle, I will try to do it again but this time only using 1/4 turn. I'll use the manual again to figure out which ones to tighten and when. I'll have the say this is a confusing process if you've never done it before.

Heres what I'm gonna do:
1. Loosen all the rocker arms
2. get engine to #1 firing position
3. tighten the rocker arms GM has listed for TDC until some resistance is felt while spinning pushrod.
4. turn 1/4 turn
5. get engine at #6 firing position and do the same as 3. and 4.

EDIT: after the 1/4 turn, should the pushrod still spin?

At some point I had the timing set to 0 degrees with it running horribly at 1200 RPM, its nearly impossible to set it when it won't start or idle. I do have the timing connector on the passenger side disconnected.

 

I never use a manual for valve adjustment. I always rotate the motor through and will do for instance, #1 intake valve when #1 exhaust is fully open, etc, etc.

 

OK, I took the valve covers off and found that one of the pushrods wasn't on the lifter........

I had a "chevy guy" helping me and we did the valves just like the book said.

It fired right up and now I have other problems to deal with, I'll start a different thread for that.

 

ok....don't try to spin the pushrods....jiggle them up and down, and once there is no freeplay then put the 1/4-1/2 turn on them, when you are tightining them down, all your are trying to do is take the slack out, not compress the lifter, the only time you should compress the lifter is that last 1/4-1/4 turn, if anything ajust them allitle on the loose side and then re-ajust them W/ the engine running...it's allot easier