Newb here: fresh 304 rebuild, first fire.

[CDriver]

I've got a 304 in a 79 CJ5 that someone else rebuilt and never fired up. Pretty much everything on the jeep is new as its a ground up rebuild that I took over. The engine is a stock rebuild but the previous owner added an Edelbrock manifold and carb. I got it fired up but couldn't get it to idle at anything below 1500 (guessing as I don't have tach on the jeep) without it sputtering out and dying. So with that high idle I still tried to get it timed. What I found was that anything in the 10-15 range would cause it to backfire when starting or run really rough. I had to advance the timing all the way to 20+(off the timing cover) to get it to run.
Does having the idle up high cause the timing to change that much even though the distributor vac signal is unplugged?

On a maybe related subject, the exhaust is brand new too. I had a shop fab up a Y-pipe, catalytic converter and muffler. The y-pipe was normal but the inlet and outlet of the cat was in the initial stage of glowing red. I don't have the smog pump hooked up to the cat yet but I wouldn't expect the cat to get hot enough to burn up the packing in the muffler.

Thanks in advance...

Chris

[BREK]

If I am not mistaken a "glowing cat" indicates a lean condition. As far as the timing advancing I believe mechanical advance can take over anywhere between 1500-2500 rpm. You need a tach to figure exactly what rpm's you are turning. Get idle rpm below lets say 1300 , set inital timing at zero, and see how it runs.

[CDriver]

Well it turns out it was the carb spacer. Edelbrock manifold/carb can't have a spacer installed. Edelbrock sells a square bore / spread bore adapter for this combo but I ended up just buying a square bore gasket. Once I figured that out, the idle immediately improved and I could lower my rpm to get the timing corrected as you mentioned. Thanks

[1980_Cj7]

If it's the first time the engine was run, did you prime the oil first and do the cam break in (assuming the cam was replaced in the rebuild)?

[CDriver]

Priming the engine? Sore subject. :) The person who built it forgot to put the oil galley plugs on the front of the engine. As I tried to prime the engine it never built pressure so I knew something was up. Luckily it was just the front two and I replaced those without much hassle.

I'm not sure about the cam being new but I assume so. The guy who started the restoration used new parts on everything so my guess is the cam is new too. I followed normal run-in procedures just in case.