351C 4V Carburetor

[red351]

4300 was not a performance carb I stick with the holley. My 4300 just hangs on the garage wall for years because it a emission carb only. Holley can be fine tuned, the 4300 not so much.

 

[clevelandcoupe]

Yes, the Holley would be a good choice or a quick fuel like previously stated. If you do not have access to a 24 hr 4300 tuner / mechanic and a reliable road service stay away from the 4300's. Better yet, buy the best one you can afford, open the box, check out it's beauty and put it on a shelf in the garage, not on the car !!!

Thanks, Jay

 

[ITMike5.0]

If I can get a beautifully restored 4300D carburetor for my car...should I?? I haven't even gotten to the engine part of my build and that's probably still a ways off. Currently there is some old 4300D replacement Holley carb on my 351C 4v. Someone once said buy the nicest 4300D you can afford and put it in a box on your shelf... LOL

So if I really want to spend $600-$800 on a carb which should I be considering? As I've said in the past I kind of want my engine to have a stock appearance but I would definitely love to have more than 266hp.

 

[ITMike5.0]

Or should I be going with something like this?  

Holly Carb

 

[Hemikiller]

Assuming your 72 has the stock spread bore intake, it's either the 4300D or nothing. The ford carb had a unique pattern that no one made an aftermarket carb for.

Your best option is to swap the intake to either an early M-code (70-71) iron intake, or one of the aftermarket aluminum options. This will allow you to run pretty much any square bore 4V carb out there. The iron intake with a thick gasket will fit a 750 cfm Holley vacuum secondary with no issues. It works pretty well to be honest.

FWIW, and this is just my opinion, the carb you linked is not a good value. A standard 750VS is perfectly fine for street use, the one below is the shiny silver with an electric choke for $200 less.

https://www.summitracing.com/parts/hly-0-80508sa/overview/

Couple it with the iron 4V or this intake

https://www.summitracing.com/parts/edl-2665

 

[ITMike5.0]

Assuming your 72 has the stock spread bore intake, it's either the 4300D or nothing. The ford carb had a unique pattern that no one made an aftermarket carb for.

Your best option is to swap the intake to either an early M-code (70-71) iron intake, or one of the aftermarket aluminum options. This will allow you to run pretty much any square bore 4V carb out there. The iron intake with a thick gasket will fit a 750 cfm Holley vacuum secondary with no issues. It works pretty well to be honest.

FWIW, and this is just my opinion, the carb you linked is not a good value. A standard 750VS is perfectly fine for street use, the one below is the shiny silver with an electric choke for $200 less.

https://www.summitracing.com/parts/hly-0-80508sa/overview/

Couple it with the iron 4V or this intake

https://www.summitracing.com/parts/edl-2665

So probably best to go that route rather than spending over $600 just for a rebuilt original 4300d right?  I haven't heard many good things about running the 4300D's.

 

[Stanglover]

While I don't have too much experience with 72 Q's, the one I had (and should never have sold) in 1980, had a Rochester  spread bore carb on it. No idea what it was exactly, but it drank fuel like it was going out of style and smoked the back wheels! To make it worse, I only found out a couple of years ago that it actually had a BOSS block in it......... why did I sell it!!

I tend to agree with Hemikiller, change the manifold for a square bore and drop a Holley 86670 or a Quick Fuel 750 on it. I run the 670 Street Avenger (86670), but with a modification to the primary plates, drilled with a 3/32" hole in each, needed because MY engine needed more air to balance the idle mixture. Doing it again, I'd go for the QF 750. I think the 770 Holley would be a tad too big and thirsty.

BTW, my original 4300 off my 71 M code sits in a box on the shelf and that's where it will stay, best place for it, but I do still have it.

 

[JD79]

I am following this tread with a lot of interest because I am considering a different carburetor for my 1973 351c 4V as well.

I noticed this carb spacer: https://www.summitracing.com/oh/parts/trd-2199

If you want to keep the stock manifold it looks like this could be an option. Any thoughts or advise?

 

[Stanglover]

I am following this tread with a lot of interest because I am considering a different carburetor for my 1973 351c 4V as well.

I noticed this carb spacer:  https://www.summitracing.com/oh/parts/trd-2199

If you want to keep the stock manifold it looks like this could be an option. Any thoughts or advise?

 I could be wrong, but I thought I did see a square bore to spread bore conversion adaptor plate. Can't remember where though. It would be interesting to find out where, maybe a custom speed shop?

 

[Stanglover]

One more thought to consider on factory manifolds and aftermarket carbs. On the 71 M code, not sure about the 72 Q code, there are heat riser passages from the exhaust ports up to the carb base. These were for the 4300 carbs, but NOT for the aftermarket ones. They need to be blocked off, either by inserting a 5/16" plug (set screw) in the passages under the carb ( see pic., circled in red) or doing  what I did a block off the passages inside the manifolds (see pic). Without doing this, you will burn the bottom of the new carb. I would also suggest using a thick insulator as well as a base gasket with the thin metal plate in it. Sorry, I don't have the FelPro number for that gasket.

What I did was to fabricate a 1" thick fiber spacer, bottom pic., but you can buy phenolic ones. The problem I found was that without these mods, too much heat under the carb caused fuel evaporation and hard starting when hot or after sitting for an extended period. The result, no more heat and starting problems.

I guess the bottom line from my experience is there is much more to swapping carbs than meets the eye. Lots of considerations before buying the new carb.

 

[goodnigh]

Or should I be going with something like this?  

Holly Carb

I believe that is the exact same Holley I have.

Works great, very happy.

mike

 

[ITMike5.0]

Or should I be going with something like this?  

Holly Carb

I believe that is the exact same Holley I have.

Works great, very happy.

mike

What engine do you have?  Did you have to add an adapter or did you change the intake mani as well?

 

[goodnigh]

Or should I be going with something like this?  

Holly Carb

I believe that is the exact same Holley I have.

Works great, very happy.

mike

What engine do you have?  Did you have to add an adapter or did you change the intake mani as well?

Pure stock early (D0AE) Cleveland.  Only thing we added was a spacer and I am not

sure it needs one.

mike

 

[Stanglover]

Also posted in thread " Carb Selection" here is a response from Summit Racing's Tech dept. regards to choices between Quick Fuel carbs on a 351C 4V.

Geoff.

 

[Kammertime]

I was reading this thread with great interest. I have a 73 Q code conv. The PO changed the intake and carb to eliminate the EGR.

The intake is D1ZE-BB and the carb is D2ZF-BB. Does that combo cause any problems when used with the 73 4V open chamber heads ?

The reason I ask is that it seems to be getting to much fuel, much more noticeable on the passenger side. The exhaust is very black and wet.

I have had the carb cleaned up once and then completely rebuilt including a new float. It seems to start OK when cold but after it warms up it sounds like it has a very lopey cam in it and the tach pulses between 500-1000 RPM. We have been assuming it is a carb problem but I'm beginning to think something may be mis-matched.

Any suggestions would be appreciated.

John

 

[midlife]

Surging of revolutions during idle indicates more of a vacuum leak issue.

 

[rackerm]

+1 on midlife's post. make sure you don't have any disconnected vacuum lines or open ports on the manifold or carb. Second check that your carb base plate bolts are torqued to spec. I think it's about 15 ilbs but don't quote me. Finally check to make sure all cylinders are firing, sometimes poor contact between sparkplug wire and plug or cap can idle fluctuations and excessive unburnt gas at the tail pipe. With all that checked or fixed make sure your choke and idle mixture screws are adjusted properly.