Did some top end work and now won't start. Help Please.
 

So i have a 2000 Chevy Silverado 2500 4x4. It has a 5.7 350 in it and noticed that the head gaskets and intake gasket was leaking so i decided to take apart the top end and refresh it a little.

So the other day i got finished putting everything back together and now the truck won't start... It cranks but just won't fire. Every odd time while i'm cranking it trying to get er to start i get what sounds to be a popping noise. Not sure what it is.

I checked for spark to the distributor and one of the cylinders and seems like i'm getting spark. I'll check the rest of them soon. I also check for fuel and you can hear the fuel pump priming and i pulled the fuel lines off and they are pumping as you can smell gas as well.

I'm really not sure what to think so if anyone could help me that'd be great..

Thanks

Is your flux capacitor on correctly?

Just kidding with ya.

Did you leave anything in the headers or anything? Had that happen to me when I took my old '83 into the dealer. Are all connectors and hoses hook back into the proper place. Had that happen with a friends 2000 2500HD. He had to due some work while he was mud digging and hook something back up wrong. (no I do not mud dig, I only go mudding)

What work did you do to it exactly? Did you pull the heads for head gaskets? Did you set the valve lash correctly? You say it doesn't "seem" like you're getting spark. Is there spark? Get a spark tester and find out. Seems like you're sure you've got fuel, so it's an ignition issue. If it's not an ignition issue, then it's a compression issue, and you didn't set the valve lash right.

Happened to me once. The valve lash wasn't set right, and it would dump oil into the cylinders and wouldn't start. After I got it set right, she runs like new.

This might be a good post to read about valve lash: 350 valve lash SPECS - ChevyTalk --The Social Network for Chevy Fans

Timing. When you pulled the distributor did you put it in the same place it was before? Did you turn over the engine when it was apart to do anything? I would bet that you will find this is your issue.