Hi,
I’m not happy with my original Autolite 4V carburator (service kit installed) on my 69 Cougar. When I put pedal to the metal, it “thinks” a little while before car starts going. Also I can’t make a decent burn out 
Have any of you replaced the original 4V mechanical carburator with e.g. 600cfm vacuum carburator and what is the experiences.
br, Markku
PS. Of course I will save the original carburator with the car
A 600 CFM vacume secondary Holley works real well. You may also want to look at a carb Sumitt is having made for them. It looks a lot like the old square Autolite from the early 60’s the float bowls are integrated into the carb no leaks and you can change the jets easily with no mess. I know a few guys who have used this carb and are real satisfied with the results. Either should fit under the stock air cleaner and they both look like they could have came from the factory.
I replaced my Autolite with an Edelbrock this past spring and it was the best thing I could have done for the car. No hesitation, power when needed for those ‘passing situations’ on the road.
I replaced my 2V with an Edelbrock intake and Performer 4V and couldn’t be happier with it.
Edelbrock and Holley are both excellent carburetors, Edelbrock is smooth and may get marginally better gas mileage than the Holley but the Edelbrock does not come with a kickdown lever for the auto transmission, there is a kickdown lever available for the Edelbrock optional… The Holley is more tunable and most universal Holley’s come with the Ford kickdown lever.
Also another slightly annoying characteristic of the Edelbrock is the fuel inlet is located in the right rear of the carburetor.
Recommend the Holley #80457
Edelbrock #1405 (500cfm) for a stock 302-351
Edelbrock #1406 (600cfm) for slightly modified engines.
If you want to stay stock with the Autolite 4300, I recommend sending it to KP Carbs in Minoa, NY for a rebuild. Kurt rebuilds the 4300 with modifications to remove all the flat spots and hesitations inherent to the 4300. I ran a factory spec 4300 with the same problems as yours, and then switched to a 4300 Kurt had rebuilt. Total difference.
Another option to stay in the Ford family is to get a 4100 and use it instead. You have to re-route the fuel line from the driver’s side to the passenger side, but under the air cleaner you won’t notice it. 4100’s work much better in stock configuration.
Of course, if originality isn’t your thing, I would go with the Holley. Given your location, that may be a cheaper alternative given the customs implication.
Good to know that KP Carbs knows how to repair Autolite 4300 problems. According their web site the repair is $235 when you send the old core. Unfortunately shipping it back and forth from Scandinavia puts adds in an extra $100. I’m wondering that original manufacturer has released 4300 into production with such annoying features back in the 60’s. Does anyone know the history of this? Has the problem been there from the new or will it just get worse during years?
My local speed shop recommends this 600 cfm Holley, since it has Ford A/T kickdown lever in it:
https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-80458SA
Have have anyone any experience of the installation? Do I have to re-route fuel line? Does the electric choke work well? Will it sit under the original air filter housing without any spacers?
br, Markku
PS. Of course I will save the original Autolite4300 with the car.
My experience with the 4300 is when they were new, good smooth responsive carburetors… But after a few years the carb tops and main body warped and leaked gasoline. Potential for an engine fire.
The carburetor you linked to would work fine but you would need the dual line kit and modify the fuel line. I suggest this carburetor which has the Ford kickdown and the electric choke, needs no extra fuel line. (may be a few $$ less expensive). Holley 0-80457S Holley Street Warrior Carburetors | Summit Racing
It has been my experience that the rebuild kits for the 4300 don’t include the small discs that belong in the vent hole in the top plate of the carb. This is where the fuel leaks come from and I believe is at the heart of tuning problems with the 4300. I couldn’t find replacement discs so I made my own from a thin rubber sheet and a thin piece of plastic. You will need to use material that is not affected by gasoline. My original 4300 has operated great since the rebuild 8 years ago.
This is very helpful. I’d like to ask two questions:
Here’s my situation – I have a 1969 Cougar XR7, 351w, auto transmission. 4 months ago my son and I took it off the road and pulled the engine to have it rebuilt. The carb was working then. Just today we finally got to the point where we tried to start it. No joy. Fuel is flowing; spark to the distributor; good cranking. So I am thinking I just need to rebuild the carb while I’m at it. But I don’t know whether to buy a rebuild for autolite 4300 if that’s not an original carb. We did put an Edelbrock Performer Intake Manifold on it.
AND the reason for the question about the spacer is because we had to replace broken motor mounts but since they no longer make them for convertibles, I had to get mounts for the hard top and that required new pedestals - which raised the engine about 1/4". Now I am not sure the hood will close when I put it back on. I am trying to figure out how to solve that problem if it happens. I’d like a small chrome air cleaner, but then wondered if I just took out the 1" spacer if that might solve my problem - but may cause others.
You guys seem to know a lot about this stuff so I’m open to learning! Any advice?
Thank you.
kevin
Kevin:
If you delete the spacer, you’ll need to find somewhere else to connect the PCV valve.
Personally, I like to use the thin bakelite spacers Ford used, with slight variations, on a number of engines in the 60s and 70s. They allow the PCV to be plugged in to the stock location, and help insulate the carb from engine heat.
They used to be plentiful in salvage yards, but aren’t so common anymore. The Boss 302 and 428 CJ versions are available as reproductions, others may be as well.
Anyhow, if it was fine before, it seems doubtful that the carb would go bad just sitting on the shelf for a few months. Personally, I’d look elsewhere for solutions to the no start problem before tearing into the carb.
On the baseplate of the 4300 they’ll be some characters stamped into the casting. You can use these to determine if the carb is the correct for the car.
Thank you very much CJ and Art. Very helpful.
I did discover that it is in fact the carb is the autolite. Thank you.
In trying to start it, I notice that fuel is seeping around the upper gastket on the front side of the carb, but that may just be because it was not starting and the fuel was accumulating.
As for the spacer, thanks also. That tells me I would not ruin something else if I try to find a thinner spacer with a PCV outlet on it. Even a repro is fine with me. I just don’t want to cut a hole in my hood. Any suggestions on a lower profile air cleaner?
I will definitely take your advice about holding off on a carb rebuild… I know it’s getting spark, fuel, and air. So the only thing I don’t know is if the timing is proper. I guess that’s the next thing I should double check. I will try to keep you posted.
This is hugely helpful to bounce stuff off you!
kevin
Okay, and I forgot to ask the really embarrassing question…how do you check timing when you can’t start the car? There must be a simple way but I don’t know what it is.
kevin
Thought I would close out this issue… Decided to break down and buy another carb. Because there were so many issues that seemed to be best. The new edelbrock performer manifold raised the old autolite too high. It didn’t fit on the manifold properly so there were vacuum issues around the base of the carb, and the carb itself was a bit leaky around the gasket. So I got an Edelbrock 1406. Solved everything - low enough to close the hood, solved vacuum issues and runs great. I did have to solve the fuel line and throttle linkage compatibility. Bought a banjo adapter to bring the fuel line from the back left to the front left bottom and then jus ran fuel hose to it. Had to add 2" to the throttle cable plate so that the cable would line up with the linkage. Once I added the kick down adapter the cable connector for the throttle was 2" too far to the left. Cut the throttle plate and added a small piece and that fix it nicely. Looks great too. So all is well - fuel line modifications, trans kick down linkage adapter added, throttle cable plate modified and it looks like a pro did it. Most of all the new carb makes the engine simply purr. Thanks for your help.
Forgot to say that the 1406 has a PCV nipple on the back so I could eliminate the spacer and still attach the PCV hose from the carb to the left valve cover.
Figured I should finish the story… Wound up putting a new Edelbrock carb on in order to match the intake manifold. My problem was vacuum leaks where the autolite connected to the edelbrock manifold. Works now although after driving and shutting it off I usually have to work hard to restart it. Don’t really know why but it acts like its flooded. It’s frustrating and if any one has a solution I’m all ears.
After you stop the motor remove the air cleaner and look down the venturi’s. If you see gas dripping you are probably boiling the gas (percolation, vapor lock) in the carburetor. Should have two solid jets of fuel when you pump the throttle.
This is why I block the exhaust crossover on engines that won’t see much cold weather use.
Should have 5-6.5 psi fuel pressure.
Thank you Art. At first when this occurred it smelled of gas after I shut it off. I did check and noted gas dripping. I assumed the new fuel pump I put on was too strong. Rather than replace the fuel pump - which is more difficult after the P/S pump and A/C compressor are on - I bought a fuel regulator and have tried adjusting it from 5psi to 3psi. It helps, but does not eliminate the problem. I am not sure what is left. I have adjusted the mixture according to the directions for the new Edelbrock carb but nothing seems to correct it completely. It’s fine when I re start the engine after only a couple of minutes. But after 10-20 minutes I have to treat it like it’s flooded and depress the throttle fully and hold it til it fires up.
Sounds like vapor Lock from the gas boiling due to heat rising in the carb, i had the same issues on my car, so i put on a spacer between the intake and the carb, and that cured my problem