Carb Replacement

7173Mustangs.com

Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

73CobraJet

Well-known member
Joined
Jun 28, 2020
Messages
147
Reaction score
68
Can any one recommend a different carb to replace my 4300d on the stock 351C Q code spread bore intake? At my patience end with this carb and my rebuilder. Don't want to swap intakes or deal with adapters. worried about hood clearance and vacuum leaks. About to use that 4300 for target practice. Thanks
 
The 4300d uses a unique asymetrical spreadbore pattern. There is no direct fit aftermarket option that I am aware of. If you are unwilling to swap the intake or use an adapter your only options are to rebuild what you have or buy a refurbished one.
 
I used a Brawler BR-67-270 on my 351C Q code with a Redline adapter. The Brawler comes with the Ford kick-down option. Started straight up and I didn't have to adjust idle speed, float, levels, choke, etc. Performs very well.

20220612_094215.jpg
 
Changed my intake with an original square bore 1970 M-code intake and used a street demon 625cfm, perfect combo for my 72 351Q
 
Last edited:
Can any one recommend a different carb to replace my 4300d on the stock 351C Q code spread bore intake? At my patience end with this carb and my rebuilder. Don't want to swap intakes or deal with adapters. worried about hood clearance and vacuum leaks. About to use that 4300 for target practice. Thanks
I machined an adapter once to use a late 70s Olds Quadra-jet. Not a direct fit but it worked very, very well. How much do you want for your current 4300D?
 
I used a Brawler BR-67-270 on my 351C Q code with a Redline adapter. The Brawler comes with the Ford kick-down option. Started straight up and I didn't have to adjust idle speed, float, levels, choke, etc. Performs very well.

View attachment 64470
Never saw that carb any where but saw it mentioned here. Where did you get it? Price for all? Thanks
 
I contacted Holley about rebuilding my 4300D carb. They recommended Allstate Carburetor and Fuel Injection allcarbs.com. They quoted me $365 for a standard rebuild with a four day average rebuild time. They also have a rebuild package where they dye the parts the original factory colors.
 
I was also going to recommend Allstate Carburetor. https://allcarbs.com/

Are you running the proper carb to EGR spacer gasket? The factory gasket was about 1/4" thick. If it's currently a thin paper gasket, that will contribute to the usual 4300D issues. I'd actually recommend running two gaskets stacked to further insulate the carb from intake heat.

https://www.rockauto.com/en/moreinfo.php?pk=11480001&cc=1107469&pt=10024&jsn=1897
Honestly, the "best" replacement option is the 70-71 M-code intake with a square bore pattern. You can then run any square bore carb you please.
 
I was also going to recommend Allstate Carburetor. https://allcarbs.com/

Are you running the proper carb to EGR spacer gasket? The factory gasket was about 1/4" thick. If it's currently a thin paper gasket, that will contribute to the usual 4300D issues. I'd actually recommend running two gaskets stacked to further insulate the carb from intake heat.

https://www.rockauto.com/en/moreinfo.php?pk=11480001&cc=1107469&pt=10024&jsn=1897
Honestly, the "best" replacement option is the 70-71 M-code intake with a square bore pattern. You can then run any square bore carb you please.
Every thing 100 percent all stock for now!
 
Thinking about options for replacing my POS 4300d on my Q code 73. I;m thinking either going with the Brawler and adapter or a 1900 series Demon carb. Demons says it will fit a square bore or a spread bore. Any one run a Demon? Thoughts on either option? Show season coming soon. Just wanna drive my car!!
 
Thinking about options for replacing my POS 4300d on my Q code 73. I;m thinking either going with the Brawler and adapter or a 1900 series Demon carb. Demons says it will fit a square bore or a spread bore. Any one run a Demon? Thoughts on either option? Show season coming soon. Just wanna drive my car!!
Just a note - the spread bore they reference is not the 73 spread bore on your 73 intake.

Replace the intake and you can run a much wider array of carbs.
 
Thinking about options for replacing my POS 4300d on my Q code 73. I;m thinking either going with the Brawler and adapter or a 1900 series Demon carb. Demons says it will fit a square bore or a spread bore. Any one run a Demon? Thoughts on either option? Show season coming soon. Just wanna drive my car!!
The Demon is not a direct fit. You will need a spacer or modify the egr plate as they need more room for the throttle blades under the carb. I have also had poor quality with my demon, missing c clip on the accelerator pump, screws not all the way in. Last is performance, I have fought a hesitation when I give it gas.
These are my personal experiences with the spread boar demon. I have a 73 Q code with manual.
 
Thanks guys! I was afraid of the fitment issue, and I do not want to replace the intake. Afraid of the mess with the egr plate and hoses.
 
The Demon is not a direct fit. You will need a spacer or modify the egr plate as they need more room for the throttle blades under the carb. I have also had poor quality with my demon, missing c clip on the accelerator pump, screws not all the way in. Last is performance, I have fought a hesitation when I give it gas.
These are my personal experiences with the spread boar demon. I have a 73 Q code with manual.
I tried a 670 cfm Proform carb. Had to modify the egr plate but the carb performs wonderful. Eats more gas but gives more power.
 
I am not a mechanic so I had someone else do the install. From what I was told, the butterflies would not open fully so he had to cut the egr plate to make the opening larger. That is my understanding of what happened. The results are amazing so far and the only problem I am having now is the car is hard to start when it sits for a week or two. I live in Toronto (cold winters) so the car is in storage right now but I anticipate a hard time in April when I try to start it.54. 9-13-12 (7)_InPixio 1.jpg
 
Last edited:
When I installed the ram air the the air cleaner was to high so I had a billet plate made to replace my egr plate for my 4300D.
This has worked well for years and although the 4300D was difficult to tune, once dialed in it has worked well for me.

Maybe a plate could be made to accommodate a square bore carb.
 
Well I was struck by lightning (twice) right after I was hit by an asteroid but I’ll be dipped my fuel make it happener is back from my rebuilder. They gave me a laundry list of stuff that was not right or missing on it. Help me understand! A guy will put it in when the weather warms up. I really appreciate the advice and feedback from everyone here. Guys gone keep the info handy just in case!
 
Back
Top