Boss 351 carburetor

[RobBrad]

I believe that was a 4300D Spreadbore 715 CFM, someone correct me if I am wrong, but I believe it was used on the Boss 351, 351HO (72 R-Code) and maybe the 71 M Code.

71 had the autolite while 72 had the motorcraft 4300d

 

[Hemikiller]

Would a person be able to even get a complete rebuild kit for an autolite 4300d being they were only on the 71 Boss?

The Autolite / Motorcraft 4300D was used on all 71-74 351CJ "Q" code engines, as well as the '72 351HO, not just the 71 Boss 351.

Rebuild kits are readily available, Walker 15508A is one.

 

[Stevieray]

I used a Walker kit to overhaul my original 4300D several years ago following engine overhaul for the first time. My carb had a plated restoration by Pony Carbs years ago when Jon was still with us. I found his modifications he had made to improve performance. I still run my 4300D but it leaves a lot of questions as far as performance. I’ve been thinking of installing an aftermarket to play with. Just got to get off my butt!!

 

[t.kohlmeyer]

Yes, you can find them. I bought a kit for a 4300D about 5 years ago at a local parts store. They even had one in stock!

 

[Billw69]

Other than the obvious Motorcraft/Autolite difference, how is a ‘72 CJ 4300 carb different than the ‘71 4300D?

 

[Hemikiller]

You'd have to do a line by line breakdown of the service parts to get into the real nitty gritty. The most basic answer is the calibration.

 

[Billw69]

Thanks, I have a ‘72 carb from a 4 speed CJ and even though I’m using a Holley on my car I wanted the original manifold to have a dedicated carb, of correct vintage. I can’t see spending $7k on a carb and was curious to identify the diffs.

Thanks for the input

 

[t.kohlmeyer]

4300D's are just rare and hard to find. They're finicky buggers and I fought one for many years. When they're right, they work great. I fought with float sticking issues and a sunken float over the years. I finally threw in the towel and replaced the iron CJ intake with a D1ZX-9425-DA Holley base aluminum intake and a Holley 750 vacuum secondary on it. Runs smooth and solved a lean miss at part throttle issue that simply would not go away. The original intake and carb are sealed in a plastic bag and box in my shop.