4300D Carb Flooding - replacement?

[F16Dad]

HI Folks - Have seen lots of notes and have now experienced flooding issues with 73 Q code Autolite 4300D 4bbl carb. Has anyone successfully replaced with a comparable and satisfactory new carb with the spreadbore intake?  Or will a change definitely require a new intake to match up? any suggestions?  THANKS!!!!

 

[Boss1Ray]

I'll make this quick. The 4300d carbs are notorious for having troubles. There is a Blue Thunder intake that is good and allows you to run a Holley. Might be a better choice for now.

I wish I had better news. But be sure and save all of your original stuff!!!!!!

Ray

 

[F16Dad]

I'll make this quick. The 4300d carbs are notorious for having troubles.  There is a Blue Thunder intake that is good and allows you to run a Holley.  Might be a better choice for now.  

I wish I had better news.  But be sure and save all of your original stuff!!!!!!

Ray

Thanks Mr Ray !  

Tim

 

[Hawk3124]

Hi was in the same boat last year. My accelerator float was stuck open and actually started on fire. My 4300 was only a few years old too. I did the blue thunder, which actually lessened the weight in the front end, i combined it with a summit 750. Runs and starts like a champ now, no flooding issues and it starts with one pump of the accelerator. Also the car wants to accelerate now no bogging or dead spots in the peddle.

 

[jpaz]

Hey F16Dad Welcome to the site! Many if not most of us have changed carbs and intakes. I had the exact same thing happen, secondaries stuck open and sprayed fuel all over my engine. I was very lucky that I didn’t have a fire.

I changed my stuff right away. Long story short I went with the Blue Thunder intake and this year went from a cheap Holley to a Quick Fuel 735. Man, what a Great carb and is about what I spent for the Holley.

Just my experience, but it really is a big difference. Summit makes some nice carbs too, but either the Blue Thunder or the Air Gap intake is your 1st step to wake up your Q code.

Anyway good luck and have fun with your ride!

 

[JD79]

I am thinking about leaving my (damaged) 4300D on the shelf as well. Is it possible to keep the stock look with a blue thunder manifold and different carb or is the height increased significantly?

 

[F16Dad]

Thanks to all so much for the advice and options!! I about went nuts looking, but FINALLY found an adapter for that one-off 73 spreadbore that would allow me to keep the factory manifold and bolt on a squarebore carb. Trans-Dapt 2199 adapter dropped right on the factory manifold and EGR plate, and bolted on an Edelbrock 1406. Fires right up and runs great. Not the powerboost I would probably have gotten from a Blue Thunder and a little bigger carb, but I really wanted to keep original as possible as long as possible.....

 

[jpaz]

Cool, glad you got it worked out!

 

[John J]

Thanks to all so much for the advice and options!!  I about went nuts looking, but FINALLY found an adapter for that one-off 73 spreadbore that would allow me to keep the factory manifold and bolt on a squarebore carb.  Trans-Dapt 2199 adapter dropped right on the factory manifold and EGR plate, and bolted on an Edelbrock 1406. Fires right up and runs great. Not the powerboost I would probably have gotten from a Blue Thunder and a little bigger carb, but I really wanted to keep original as possible as long as possible.....

I put a 1406 on my car 2 years ago and have no issues. Starts now when it cold out now and idles great. My motor craft 4300 D leaked fuel everywhere also. Its now sitting in a box on a shelf.

John J

 

[Andy 351C]

By using the adapter and new carb, did it change the overall height much? I have a 73 Q code as well, along with Ram Air. My 4300D is working pretty good now....but I had it apart way too many times, to bend the float bracket, so it wouldn’t hang up in the bowl. I’m always leery of it flooding again when I take it out and I don’t trust it.

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[F16Dad]

By using the adapter and new carb, did it change the overall height much? I have a 73 Q code as well, along with Ram Air. My 4300D is working pretty good now....but I had it apart way too many times, to bend the float bracket, so it wouldn’t hang up in the bowl. I’m always leery of it flooding again when I take it out and I don’t trust it.

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Hi Andy - the adapter is 0.85" tall - so it does increase the height..... we were a little worried, but i don't have the ram air and it fit fine. I would expect it would push the envelope with that add-on since it  the ram air foam seal has to fit well around the air cleaner. 

 

[Andy 351C]

Thanks for the info Tim. I wonder if I could eliminate the EGR plate to gain the thickness of the adapter plate? I’m not sure if that’s even feasible.

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[F16Dad]

Thanks for the info Tim. I wonder if I could eliminate the EGR plate to gain the thickness of the adapter plate? I’m not sure if that’s even feasible.

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From what I've learned from all the wisdom on these pages, is that the stock manifold has a small "v groove" cut into it that aligns and locks in the EGR plate, so if that plate is removed, there is the problem of dealing with that remaining groove in the manifold that several folks noted is problematic if not impossible to seal off when combined directly with a new carb with a smooth flat bottom plate (even with the gasket).

 

[Andy 351C]

Got it.... I believe down the road, I’ll replace the intake along with the carb like most do. For now it’s running pretty good, so I’ll stick with the 4300D. Thanks for your input, it was very helpful!

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[Raven]

Got it.... I believe down the road, I’ll replace the intake along with the carb like most do. For now it’s running pretty good, so I’ll stick with the 4300D. Thanks for your input, it was very helpful!

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 Not sure if this helps as this takes a bit of nerve and sounds a bit shade tree. I had to keep mine to the numbers and was tired of the leaks and had problems with aftermarket carbs. Hard to do to 1 of 398 HO carbs but its done now. Learned this from a old Ford mechanic. 

 Bowl cover distorts is the downfall of this carb. Took bowl gasket out. Fit cover by tapping flange GENTLY with wooden dowel on a flat steel plate until it was in .001 gap all the way around. Then put in the thicker .045 gasket. Ran just shy of 2k so far with just a little wetness at the gasket. You may want to just try the gasket.

 Test stand Dyno report had torque and Hp readings to 5800 better than the test Holley or the Edelbrock when I rebuilt the engine in 2017. I like the drivability better also. R code with quench heads along with cam selection may be be why it likes the air fuel ratio, who knows. I found the Idle stop solenoid a must to shut down properly with the higher compression. Dieseled terrible with the other carbs and starts best with the 4300D. Zero pumps as long it has not been sitting for a week or cold. Just saying that they can work well if set up right.

Gasket Link

https://quadrajetparts.com/ford-4300-4350-bowl-cover-gaskets-p-1984.html