Hey guys, new here and glad I found this place, as I have several projects with these trucks that I'll be working on. Some currently in progress and others down the road. I come from the world of diesel performance, so I consider myself to be at least mechanically inclined and fairly well equipped, but... Not familiar with the ins and outs of these trucks and in particular the engines.
The truck I am currently working with is for my friend's son. It's a 77 GMC (heavy duty half). Single cab short bed 4wd drive, with a small block 400 and th400 trans. The truck was losing lots of water and obviously getting it into the combustion chamber with how much was coming out of the exhaust. Seems like the likely culprits would be bad head gasket(s), cracked head(s), or intake manifold gaskets. Since the truck wasn't running poorly, like it was losing compression anywhere we decided the safest bet was to go with the intake manifold gaskets.
Replaced the gaskets, which were pretty hammered, put everything back together and it won't start. Definitely getting fuel, and air, so I would say no spark. I've tried just about everything I can think of to make sure that the distributor is set correctly and still nothing. It sputters and pops but won't fire. I tried turning everything over 180* to see if I was on the wrong stroke, and got some really nasty backfires. Which in assuming is because the spark was occurring when the valves were open. So I went back to the other way but still wouldn't fire.
To set the timing, I'm lining the mark on the balancer up with the timing indicator on the front cover. Then installing the distributor, then lining the cap up with the rotor pointed at the number 1 spark plug wire. Once it's set I've even tried twisting it to see if I can find a sweet spot where it wants to run, but nothing.
Are there any steps I'm missing things that I am doing wrong? I hate to go throwing parts like a new distributor at it if it's user error. And the fact that it ran prior to this makes me think that it should just fire right up.
Thanks for any help and insight.
Sean
1
