Timing?

[Rip]

The motors a 350 4 bolt with a four barrel carb and HEI coil in cap. Its in a 1980 stepside. There was an intake manifold leak so i replaced it. I cleaned out the egr passage cuz it was blocked and failing smog. I drove it one day and the rocker cover gasket started leaking. I figured do the head gaskets too. After i reassembled it i can barely get it started. It still runs super rough and seems like the timing is way off or something. One cylinder is still 30 psi low at 120, making me think its rings. I have spark at all cylinders. Its a new carb, cap, rotor, plugs and wires. It seems the low compression would affect drivability but not actually starting as much. It backfires and shakes harder than normal when trying to start it. If the timing is supposed to be 8 degrees btdc. Is the timing mark supposed to be set there at the scale, with cylinder #1 on tdc compression, when i seat the distributor with the rotor pointing at terminal #1, or is it supposed to still be at 0 when i seat it? Any help would be appreciated.

[Captkaos]

First if it isn't starting make sure you aren't 180 degrees out.  So verify you are on top dead center not bottom.  8 degrees initial is a good start.
Once at TDC point the rotor at the #1 plug position and make sure you have room for advance/retard to get it right..  Also make sure that the outer ring of the balancer hasn't slipped.

[Rip]

I lined it all up again and the timing mark at 8 degrees btdc. It starts, albeit hard, but runs rough and dies as soon as i put it in gear. Ive tried moving the distributor but cant get it any better. Would the low compressuin on one cylinder cause it to be this bad?

[Rip]

Does it make a difference where to set the initial timing if it has vacuum advance?

[thefarmboy21]

First let me make sure I've got it right....you replaced the intake gaskets, or intake manifold itself? Then you had valve cover leaks and decided to pull the heads and change the head gaskets?

Well IF you did pull the head and change head gaskets and you put the distributor back like it was (not 180 out) and you did NOT bother the camshaft or timing chain then here are my thoughts of possibilities:

1. More than likely you don't have the valves adjusted correctly and at least one cylinder is too tight causing low compression.
2. You got a bad gasket and isn't sealing one cylinder OR you pulled a head bolt thread or improperly torqued it = low compression.
3. You got some "debris" in that cylinder and ruined the rings, piston, valves or combination of the three.

AFTER you check you valve lash....A way you can try to check that cylinder is take an old spark plug, spark plug non fouler, or compression gauge tube and rig an air fitting inside....put air pressure into that cylinder. Make sure both Valves are in closed position....air coming out tailpipe is exhaust valve issue, air out carb is intake valve issue, air in radiator is bad gasket and air coming up from the inside of the oil area (inside motor) is ring/piston issue.

[Rip]

When the valve covers started leaking i did a compression check and it was low on bkth sides a couple cylinders so since i know the truck sat for a few years before i got it i figured do the head gaskets now too. Tne other cylinders are good now so i know the gaskets were the problem.on them. The intake gaskets were replaced, not the intake. The cam and timing was left alone. Prior to starting anything it ran pretty good for having an intake leak and all.

[BADAZ chevy guy]

Back to basics. Make sure you have all the wires in the right order. 1,8,4,3,6,5,7,2

[Rip]

I got it figured out and running smooth and steady.  Now to replace a pinholed radiator...

[Captkaos]

What was the issue?

[BADAZ chevy guy]

Yes... What WAS the issue? I curious as well.

[Rip]

I ended up replacing the coil. I spark tested the old one and the sparks were light yellow and weak looking. The new coil gives bright blue sparks that audibly snap. Timing and carb adjustment have it smooth and steady, even on cold mornings. It still failed smog though. The nox is too high. Further idle nd timing adjustments made it better, but worsened some other gases. Would a less than perfect cooling system cause temps to go up enough to fail on nox? Its true duels, with a new cap and rotor, coil, plugs, wires, egr valve, carb, fuel pump and filter, cats, mufflers, and pipes. It tested slightly rich so i turned down the mix, but everything ive read says to turn up the mix to combat nox...