I built a 77 olds 350 with the iron intake and a Q-jet. Pretty much a stock build. I'm having trouble getting it to run consistantly. I'm thinking its an intake leak. The engine runs decent when cold but not perfect, when it warms up, it barely idles and I have to two foot it most of the time. It runs pretty decent on the gas but it could be better. I swapped the carb to make sure it wasnt that. Next I was gonna take the intake off and redo the gasket(since I have a coolant leak anyway) but I was wondering if anyone has used regular intake gaskets(like on an sbc) instead of the valley pan? I dont know if I should use fiber ones with the stock iron intake but there is an edel intake on craigs right now. I wanted to check with ya'll to see what ya'll would do. Thanks, Sam

 

Where did you set the initial timing? It should be 20° @ 1100 RPM. Make sure to unplug the vacuum advance and plug the source before you set it.
That said get a can of carb cleaner, start the car and spray the intake at all of the runners, base of the carb and then all of your vacuum lines. If the idle picks up you have found your leak.

 

I should have mentioned that this is on a 90 cadillac brougham and its a computer controlled carb setup. I found a battery connection that was loose and the problem has not returned as bad. I have a feeling it will be back because the battery connection was good before. I will try the timing again but my gut says the intake may have a leak somewhere.

 

So you replaced the 307 with a 350. Rock on more is better .
The computer system can handle it so long as the build was basically stock. Like I said just go around with a can of carb cleaner and spray any potential vacuum leak. If the idle picks up you have found your issue.