Big-block Ford running strange-help?

First off here's the quick specs of the engine, 429 bored/stroked to 506ci, big solid cam, dual quads, new TCI 3-3500 rpm torque converter, old stock C6 auto. After it warms up, it has a tough time idling, the rpm kinda surges and sounds like the engine may cut out. If I idle it up, it seems to only bring up the idle in park. As soon as you drop it into drive, the rpms drop right back down low, running kinda poor. Today I got on it a few times and sometimes it seems to "pop" or skip a little if you hit the throttle just right. Otherwise it cruises along just fine and has plenty or power. I do know the carbs aren't that great though. They were set up as best as my engine builder could do but they still are tired. Any thoughts? Vacuum leak or ****py carbs? Any thoughts would be great, thanks
-Dean

 

Sounds like it's a vacuum leak. Withthe car running at as low an idle as possible, spray carb cleaner around the base of the carb and manifold. Also spray vacuum lines. When the idle picks up noticeably, you found the leak. Hopefully it's just a cracked line or bad carb gasket.

 

Also check the intake manifold-head junction for vacuum leaks. Re-check timing, make sure you've got the plug wires in the right order (don't laugh, it happens sometimes), make sure the dizzy isn't worn out, got a good coil? and make sure the carbs really working and tuned right. Double check for proper valve clearance (hot) as well.

 

Big cam,Lo engine vacuum causes problems with power valves,what carb are you running and how much vacuum does the motor have? how much base timing does it have and what dist is it curved? Big cams want lots of base timing.

 

Crossed wires is a common problem on 385 series Ford engines, and the symptoms can be just as described. Check this closely. But, it does sound like you've got a vac*** leak.

 

All the above.. AND check the power valves in the carbs ESPECIALLY if they're HOLLY ......... MY 514 Ford did the same thing a few times and every time it was the power valve ( single 4 bbl)

..... jersey Skip

 

Also make sure the power valves are correct. When your using multiple carbs you need to make sure the PV opening point is lower. Typical PV opening is 6.5"Hg (a #65 power valve), with dual carbs I'd start with a #35 PV in each carb and work from there.

-Bigchief.