Please help It won't start!! I have replaced head gaskets, rotor, module, distributor cap, wires, plugs, coil, timing chain, carb. I got the timing right I'm sure on that. what else could it be that I haven't replaced? Computer gives code 12. It will spit and sputter sometimes but most of the time it just cranks over without any sign of starting. Please help!!!

Code 12 means the diagnostic system is functional. Nothing wrong with 12.

Are you certain you have the distributor stabbed correctly? Even if you are, pull it out, bring the engine to #1 TDC firing, and stab the distributor and set it up correctly.

yes, I am absolutly sure I've done It 3 times and It's still the same.

are your valves adjusted correctly? dot to dot on the timing chain isn't TDC compression.

They should be I did It the way the book said except I only did 1/2 turn preload. All the valves open and close and I have compression. Would one of the sensors be bad enough to not let it start? I'm thinking maybe the ignition spark control module the one that is on the firewall not the ignition module in the distributor. This is the one connected to the knock sensor maybe it's bad or the knock sensor itself. I tried to unplug it and the sensor but no changes so I don't know.

if you look at the adjuster nuts on the valves.. is the amount of thread exposed more or less the same.. if it's not, the valves aren't right. to take the ESC/ knock out of the loop, unplug the timing bypass connector. if your valves are good, the rotor is in the right spot and you've got fuel, it will start. I'd re-check the dizzy, have someone bump the starter while you put your thumb over the spark plug hole to find TDC compression, then look at the rotor. it should start even if you're +/- 10 deg.

Ok, I got it running I readjusted the valves I guess they weren't right but now it runs for about 5 seconds with me feathering the throttle it won't idle unless I have my foot on the gas then it starts to backfire why is it doing that? I haven't adjusted the timing because I can't get it to stay running.

sounds kinda like your valve lash is still a tad too tight..

I tightened it to zero then 3/4 turn is that too much? That was after I tightened it till I couldn't twist the pushrod with my fingers then a 3/4 turn.

How are you setting the valve lash? What order?

#1 tdc Firing exhaust valves 1,3,4, and 8 Intake 1,2,5, and 7. then I turn the crank 1 revolution to tdc then I adjust exhaust valves 2,5,6, and 7 and intake 3,4,6, and 8. Did I do it right?

Ok I readjusted them with the EOIC method with a half turn after zero. It's still backfireing and it won't stay running. Please help!!!!!

It sounds like they're still not adjusted right.

The problem is, one person's idea of "just barely able to turn" the push rods, can be VERY DIFFERENT from somebody else's.

Back them all off about 1 full turn. It should then at least run, although a few may clatter. Get somebody to sit in the car and keep it running, or turn the idle speed up, while you adjust them with the motor running, as described in this thread here.

hmm try the fuel filter...u never know might be somethin simple lol

When you are adjusting the valves, zero lash means zero clearance, no up and down movement. You will still be able to turn the pushrods. Tighten slowly while pulling the rods up and down until there is no clearance, that is zero lash, then turn the additional amount. Usually on a small block Chevy the nuts end up about 4 threads down from the top. It sounds like they are too tight.

Thank you I think that's what I'm doing wrong. What should I do after zero? A 1/2 or 3/4. It's a hydraulic flat tappet cam.

Yes.

Just make sure you find zero lash first. That's your issue; you're going WAY past zero lash, then adding the preload besides. You've got rockers that are WAY too tight.

The actual preload # itself makes very very very little difference. As long as it's consistent, and somewhere in that range of "reasonable". Pick a number, and stick with it, and get your car running.

Back them all off at least one full turn from wherever they are now, then start the motor, and adjust them with the engine running, like the instructions have been posted over and over again. Your problems will magically disappear. Just put up with the backfiring and the clattering for a minute or 2, and it will be all over with.

Ok I adjusted the valves again this time I tightened them till I couldn't move the pushrod up and down with a 1/2 turn after that.There are about 4 threads from the top. So I should be right now right? I couldn't get it started I think because it was flooded. I took out a plug and it had gas all over it. I'll try again tommarrow. I hope it starts. If it don't Ill let you know.

Well I got it running but it still backfires. It runs ok once I start it but after like 5-10 seconds it starts to backfire and it stalls. Could no fuel cause backfiring or is it a timing issue? Because If it's fuel maybe the carb is screwed up. I do have to pump the heck out of the pedal to get it to start sometimes. If it's timing I don't really have it set because I can't keep It running long enough to set it. I tried to unhook the 4 wire hookup to the computer it ran a little better but it still backfired. Could the computer be retarding the timing making it backfire? Could my ignition spark control module be bad? I also unhooked the knock sensor too but still the same. What could it be I'm pulling my hair out here? Please help!!!

Ok I got something new how come when I unplug the computer from the battery the car runs better? There is a connector at the battery that was accidently unplugged and it ran like it was new. When I plugged it in it stalled. How can this work without a computer? What could cause it to do that is my computer shot?