383 Fuel Problem

Tech Question

Jackson Boyd, Toronto, ON, Canada, 1967 Dodge Charger 383

Hi Richard,
Big Mopar Action fan here in Toronto ( I am notbig, I mean I like it a lot) Cant get enough of your tech, thanks.

I did a 4bbl intake and carb swap on my friend’s stock ’67 383 2-bblCharger. I used a ’68 383 4-bbl factory intake and AVS carb for a 383 auto.
My problem is I cant get rid of the off idle stumble. After you get going it goes great. I took it back to the carb shop where the carb was rebuilt, the shop saidthey thought the engine had an aftermarket cam and that the carb was finethen put in the richest needles available, it helped a little. But now myfriend says it’s still no good ( he’s a bit pissed at me) What usually takes me 4 hours has taken days of screwing around. I pulled the whole intake assembly off and replaced the gaskets thinkingthere was a leak. I used the 2 paper gaskets over the tin pan.

No change.
When I install the vacum gage to manifold I don’t get a steady needle,thats what made me think vacuum leak and what made the carb guys say it hada cam. Others say that the AVS is shit and I should bolt on a Holly. I say I have done this swap before a few times and that the AVS and otherCarter four barrels are a good street carb. I also threw on an Edelbrock afb 750, that cleared up the stumble completely but was running way to rich.(smokyrich)

Could You please give me some wisdom to use on this.
Thanks Jackson in Toronto

Jackson-

There’s lots of possibilities as you note.

First – be SURE that, for the SLIGHTEST movement of the throttle lever,there’s a “solid” squirt from the pump nozzles. No lost motion, no “fizz”.if not, take the air horn (top 1/2) off the AVS and put a kit in it, beingsure to replace all accel pump parts. The fluctuating vac gauge belies this,but, still, experience….(I’m assuming it ran fine with the 2-Bbl….)

Then, if still NG (or tests OK), try this messy test: fill a squirt can withSAE 30 oil. With engine at idle, oil down the intake/head junnction, oneside at a time. If the idle changes – there’s a vacuum leak at the manifoldgasket. Disassemble and use only the steel gasket with a nice, thin, evenbead of RTV. While off, inspect the manifold CAREFULLY for hairline cracks.

Rick