Carb Tuning / Vacuum Problems?

[Moparhead64]

To check for a vacume leak get some starting fluid and CAREFULLY spray on one side of the carb until you ve gone all the way around then the intake gaskets at the head if the RPM picks up you have found the leak. I like to use the black permaseal gaskets on the exhaust for both manifold and headers they cost about $20.

 

[DMaloney]

Is the big vacuum port on the rear of the carb plugged. It is in the center facing back under the bowl. Looking at the pick I didn't see a hose coming from it and usually it goes to the pcv valve. That could be your hissing sound and cause it to drop the rear cylinders. alot of guys forget to plug this port.

Excellent work, that port has been sitting wide open the whole time. DOH!

I'm kind of glad you didn't point that out for a while, though, or I might not have ever realized my coil was wired backwards.

Nice to see you got it figured out BUT the same suggestion was made in post #4 and 5 of this thread.

Are all the vacuum ports attached or plugged?

Firing order, double/triple check it.

Plug off ALL the vacuum ports at the carb. Eliminates any secondary leaks

Check float level and baseline the idle mix screws at 1.5 turns out.

Set the timing at about 16-18* initial.

If it idles above 1000 rpm, it may be bleeding mechanical timing in and that gets pulled out when you drop it in gear. You time it for 12* at you 1300 rpm and it drops to 7-8 when in gear at 800 rpm. Your engine should idle EASILY at 850 rpm, imho.