Intake manifold choices
I read your initial post again. I doubt an AG intake will fix your problem, nor will a bypass fuel system. [1] What type of pump do you have now?
[2] Do you know how much HP the engine makes? An estimate if unknown. This needs to be considered if changing f/pumps.
I am surprised that most think an air-gap isn't the 'fixer' I thought it would be. That big free-flow airspace between the runners and the valley I figured would be The Way to resolve the problem. I wanted and air-gap when I bought the parts for this engine...it wasn't available at that time, IIRC.
Reading that a fuel-bypass setup might be in the 'no' column too...well, now I'm all sad and morose about it all!
I am using a Holley Red electric, mounted at the tank.
I have not taken this setup to the track and there are no chassis dyno choices within a couple hundred miles. This engine is a bit less than what I ran a high 11 with...once.
HP isn't much. It's a 10:1 iron head motor with an HE-3844 cam:
INT .535" 237º@.050" .286"@.008" 108ºLSA 13.5ºBTC 43.5ºABC
EXH .540" 243º@.050" .290"@.008" 52.5ºBBC 10.5ºATC
It might make a hp/cid. Seems owners generally think they have a good bit more ponies under the hood than they actually do. I am not of that persuasion.
I don't think the intake swap alone will solve it, after reading. you say the float bowls are not hot to the touch. You may be experiencing fuel percolation in the lines, instead of the carburetor itself. Pay close attention to where the fuel lines run. Are they near any heat sources? Getting the fuel lines away from heat sources will certainly help. Also, a systematic approach will be best, imo.
More nix to the air-gap...although you DO say, not 'alone'. No argument from me...I just thought the idea had more merit than it probably does.
The fuel lines are well away from the exhaust and insulated. Yes, a systematic approach is the best I'm sure. As said, I have replaced iffy needles already (no test since) and have a throttle bracket due in Friday that will make the addition of my 1/2" phenolic spacer easy to get done.
A return regulator is probably next. I don't expect the problem to completely disappear, but it getting considerably better can't be off the table.
Thanks, summore, for good points made.