Time for New vs. Rebuilding Carburetor for '71 road runner 383 4 Speed - Is My Carter AVS 4966S The Best Choice?

[road robert]

Hello Gang, my '71 road runner caught the bird flu and I don't know if it's fuel or ignition. I have a Carter AVS 4966S that was remanufactured then rebuilt recently (March 2023) by Dave Woodruff (Woodruff Carburetor Specialties advertised here at FBBO). At that time when I got it back I popped it in along with the distributor I sent him (he also put a curve in my distributor) and it ran great. But now after 2+ years my distributor is getting worn (shaft bushing) so I replaced it from halifaxhops (Ray Brenner also from FBBO).

My bird is stock except for a purple camshaft that I have no specs on - I just want it to start up cold and hot, run good from idle to wide open and overall for street cruising, NOT racing! So my questions are:

1. Which brand and model is the BEST carburetor for my '71 road runner 383 4 speed car?
2. Can I buy a brand new carb or is used (rebuilt/refurbished) better?

Thanks everyone!

Purple cam:

 

[T2R9]

The 4966 is a low performance carb used on C-bodies. A new 650 CFM AVS2 would be a nice upgrade if the issue you have is carb related. What is your ignition system? Points, electronic? Whats the timing set at?

 

[road robert]

I just swapped complete distributor from halifaxhops (Ray Brenner from FBBO with new points, condenser, rotor, cap) & recent new Champion plugs. Repositioned and verified distributor rotor at #1 position at TDC compression stroke (plug wires were shifted by 1 position from before pics I had), plug wire firing order correct and timing @ 10 degrees before TDC and confirmed/set point gap for 30 degree dwell angle. Car starts right up, idles and runs OK at cruise speed (higher RPMs) but shudders, spudders and shakes at lower RPMs or startging off from dead stop. When I'm going through the gears easy I can hear valves rattling and when I floor it 4 bbl kicks in and goes but I can hear slight pinging. Mechanical advance works I can see timing mark moves with RPMs, seems to run better with NO vacuum advance connected to distributor (I found out it was plugged for 5+ years ago from previous owner - "hidden" screw inside tubing) from ported carb vacuum to distributor lol.

 

[Bee1971]

Reading your initial post #1 and now post #3

Then why are you concerned about the carburetor ?

Give halifaxhops a shout or a phone call and maybe you could verify the distributor is in good working order , could be something simple as a defective set of points or condenser, or maybe he might want it back to verify or test on his distributor machine . Your 100% positive your firing order is correct and the plug wire orientation is correct ?

Ray is a great guy , he probably is at the Mopar Nats ? Did you try and reach out to him ?

 

[road robert]

Thanks T2R9 for the carb info.

Thanks Bee1971 - I'm 100% sure about firing order is correct and the plug wire orientation is correct AND distributor rotor pointing to #1 TDC (I numbered the cap and wires to be certain).

Since swapping the distributor I spoke with Ray then had some troubleshooting to do first before sending it back. I bought a spare set of points and a condenser from him as well to try and also wanted to put my original distributor back in to see what happened (all that was inconclusive). However I may have just found the smoking gun:

*I just removed all the plugs and connected each wire directly to the coil with the corresponding plug connected and rested on the exhaust manifold then jumped the starter relay to see spark - this way I verify all wires & plugs!

**Plug #8 was fouled (wet) and it appears that the wire is bad (this one has the 45 degree angle on it and the boot pushes very deep onto plug to connect) and confirmed bad with a known good spark plug. I might not have had it snapped all the way on (replaced plugs before the Carlisle road trip - it starting acting up there and was intermittent with the original worn distributor since) causing it to arc and burn?. I will replace my wire set and get a new plug hopefully that will resolve my issue...