Semi rebuilt motor started, then shut off, wont start.

[80Grand_LeMans]

Just recently finished my semi build of a 76 olds 350. Here is whats on it so everyone knows:

Stock block and rotating assembly (7x,*** miles)
New oil pump (Melling high volume, bolt on screen)
Edelbrock double timing set
Edelbrock performer cam/lifters/springs
Edelbrock performer rpm intake
Comp roller rockers/pushrods
Olds 330 heads
New water pump
Holley 750 Carb
Full length headers

Ok, so I ran into a problem with the mechanical fuel pump not fitting because of the timing chain being larger. I hooked up an electric fuel pump and regulator with return line. I set up the radiator and battery and such so I could break it in on the engine stand. I ended up getting it to actually stay running today. I was holding throttle at about 800rpm when we disengaged the starter, brought it up to about 1k, then climbed to 2k so I could get it at the break in point. A few seconds later it kind of hesitated, backfired a little bit then shut off. It won't start now. It ran a couple times after but once we stopped the starter it would just shut off.

Any ideas? Could it be the fuel pressure? I need to get a gauge and see what its set at. It wouldn't start at all the last couple times I tried, just turn over, sound like it wants to, but wont. I double checked timing over and over it should be running where its at. What would the proper fuel pressure be for this motor? thanks.

let me know if I left anything out.

 

[t5montecarlo]

You said it runs in the start position, but not in the run position, so it sounds like an electrical issue.

 

[80Grand_LeMans]

I ended up getting it to run, somehow the timing was off, even though I double checked it. Might have something to do with the vac advance not hooked up by accident when I got it to run that first time.

 

[t5montecarlo]

so you got it to run well enough to break it in properly?

 

[80Grand_LeMans]

Yeah, it fired right up and ran great. It started overheating though about 15 mins in so I had to shut it off. I replaced the water with actual coolant thinking it might help but I just didnt have enough air being pushed through the radiator I guess because i started getting too hot again the second time I started it. That was another 15 mins though so I hope that was good enough. Once I get it in the car I'm going to cruise on the highway at 2k.