Replacement Carb Reccomendation

[pflug]

I always try to avoid diagnosis over the internet LOL- but, as mentioned previously, the first thing to check on a Holley that's always super rich is the power valve- one backfire can rupture them and in simple terms your whole carb goes to full load enrichment.

The power valve basically works as a restriction to extra fuel for the main jets and senses vacuum- when vacuum drops to the the value the valve is designed for (indicated by the number stamped in it) it's at full enrichment- this will also happen if the diaphragm is ruptured by a backfire- they can be sensitive and its a common issue.

This can be checked and repaired without even removing the carb- when removing the bowls put a rag and small cup or even spray can lid (if it doesn't have a hole) under one of the lower screws- loosen the screw and let it drain and you won't be dumping gas all over the engine.  With the bowl off you can also check the float and needle and seat condition as well as the jets. 

We always had a huge Holley List number book which listed every carb both OE and aftermarket and listed what specific parts were originally used (jet sizes, power valve, springs, etc) which could be used as a starting point to get back to original specs.

  If you want to be able to adjust your overall carb fuel level externally the standard side hung aftermarket style bowls will fit- since there's already a chunk of hose on the line you'd just use a banjo fitting and the line will attach in the same spot

[Wayne]

Not sure of your budget but I went with a quick fuel and that's what I always suggest. 

I don't think you specified but does it run rich at idle or part throttle or WOT? 

To be able to really dial in your AFR's at idle a carb with four corner idle mixture screws is ideal.  Those carbs cost more money but they are very adjustable. 

[Aloha Randy]

As far as the Holley equipped 383, I have been lucky to have a 1970 Cuda and now the 70 Challenger that both had the Holley 4160. My 68 Road Runner had an AFB and the 69 Charger had and AFB also except a later model.

[Aloha Randy]

Thanks for your input. Since we moved to Hawaii I do use the internet sometimes to get my mind back in the game as there is little local help here. It also thru me as 2 shops on the mainland looked at the car and did nothing it seems. Thanks for the leads and I appreciate it much. Ordered a Holley kit to go thru the carb and will use that as my starting point noting the jet, power valve etc sizes.

[Aloha Randy]

Idle and off idle are where I feel and hear the problem, 50 - 60 mph it runs fine. Black soot on rear bumper after 200 mile drive the other day. Breaking in new motor so I need to get this fixed so not to damage rings seating etc.

[dodj]

I would get this QF 650 rather than the Holley IMO.
https://www.holley.com/products/fuel_systems/carburetors/street/parts/HR-650
They are far more adjustable.

Depending on your engine, I may be tempted to look at a 750cfm? I had a 600 on my 318 so pretty sure a 383 would have no issues with a 750.

[EV2RTSE]

I was hoping MrLee would chime in here, he had a similar issue with his original Holley 4368 for his 1970 383 R/T. We had found an original core and sent it to Harms for a rebuild, and it came back looking like a work of art. Went to run it on his newly rebuilt engine and found it running massively rich. He fiddled around with it for a while with no improvement. Changed power valves, jets, on and on. There are posts here about it. Then switched to a rebuilt Carter AVS that I have and the car ran great. Called Scott at Harms and was basically told that he does not warranty these original 4160s because they were a crappy design and oftentimes basically trash right from the factory. Would have been nice to know that up front but lesson learned I guess. I presume a warped or bad casting or something at this point. So for 6 or $700 all-in he now has a nice piece of garage art. Ended up running my AVS for a while and is now on AVS2, I think 800cfm, after talking with Mike Bonsanti at HP Motors. Agree you should be just fine with a 750cfm whatever you end up going with.

[HP_Cuda]

Let's do the math here fellas.

Holley rebuild kit - 30-50 bucks depending on what you want and carb type
Time investment in Holley rebuild - priceless

It's really not that hard to rebuild a Holley carb. For Scott's feedback, I don't really buy it unless you dropped the carb on the ground over and over again and had sealing or warping issues. Here is a good starting point: https://www.motortrend.com/how-to/tuning-holley-carb-made-easy/

If you want originality then the carb you have is closer to what it was. If you want a more performant and adjustable carb then the ones mentioned before like a Proform could be up your alley.


B

[Aloha Randy]

Doing the carb rebuild Thursday. Time is what I am working against. The carb suggestion is a backup if the rebuild does not give the results I am looking for. Getting a part shipped to Hawaii is slow and expensive, in many cases more than the part itself. Ordered a dash pad and it was $518 to ship it!

[pflug]

Rule of thumb for carb size is usually CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456- figure 80% VE, if its the stock HP cam its probably good to 5500 RPM max- so in stock form 600 CFM is flowing enough air but you may want a bigger carb if you do any hot rodding

[Aloha Randy]

Yes its stock but I was leaning to no more than a 750 but a 650 would work also for me. Thanks for your thoughts and info! Aloha!

[Chryco Psycho]

AS I  have proven over & over 2x the ci is a far better guide for carb size than the "math", 383s work great with a 750 .

[Mr Lee]

@Aloha Randy Wondering how this turned out?
As my brother EV2RTSE stated, yes I had the same carb on my car that was restored by Scott Smith of Harms.  It always ran rich and I could never figure out why.  I went through the carb several times.  At first I knew nothing about carburetors but educated myself by reading as much material as I could on how carbs work and how to tune them and still couldn't figure out what was wrong.  I adjusted floats, mixture screws, I tried different jets, power valves, vacuum secondary springs, etc etc etc. And my plugs were still black. 
Smith told me that that is the only carb he doesn't warranty because they're so problematic.  Just saying, that's what I was told by the expert.  I eventually gave up on it. 
I threw an old Carter AVS on there and it immediately ran better, stronger, way more responsive and my plugs no longer fouled so it was definitely the carb.  It now sits in a box.   

[Aloha Randy]

Actually I am working on it this morning to get it running! Yes, after rebuild, I too gave up on that carb and went to a new Holley 4160 #80459SA, 750 cfm. I had that same old carb on my 1970 Cuda back in 1973 and I always had it apart. Shortly after I got the new carb on, the existing electronic ignition went out and I have since replaced all that was there to a stock setup with Pertronix Ignitor 2 ignition. Also, due to the fuel drop on the old carb, an ignition backfire blew out a seem on the right rear muffler. Some days are better than others.
So day, muffler goes on and car hits the ground again and hope that all the progress shows results! I will let you know.

[Blowout]

@Aloha Randy any update on this?  Did the new Holley perform well on that 383?