Engine 1973 Mustang 351 2v Cleveland Carb Question

[Walter Sparks]

I recently purchased my first Mustang for my 15 year Old son. I have a 1967 GTO that I have had since I was a teenager, so he has always wanted a American Muscle Car. Anyway, I am not much of a Ford man, at least with cars, never had anything but Ford trucks. Any way I just do not know a whole lot about the late 60s early 70s cars/motors. I purchased the car and it has headers and a high rise intake with a 4 barrel carb. the rear intake gasket had blown out so I got a new gasket set for a 4 barrel motor, then I realized something was up, I then did some research and found out that I have a 2V motor. My Question is.. Am I gaining much with the four barrel and high rise or should I put a 2 barrel back on it??? I noticed the huge difference in the head ports which makes me think I may be just dumping fuel into a hole with not enough air flow. Any hints or advice about anything to do with the car would be appreciated.

 

[clement]

itll be fine. if its too rich jet it down, its no big deal. a lot of guys prefer the 2v heads for their low to midrange power. the 4v heads are VERY LARGE and a lot of guys can get them to run right. even a 2v Cleveland will run better with a 4 barrel carb and decent intake.

 

[Hack]

Clement is right that the right 4 barrel carb and intake can help wake up the 2V Cleveland. Some are better choices than others.

If you post what the intake is someone can probably tell you whether that particular intake is a good choice on a 2V motor. Based on your description the motor could have a non-factory cam or other internal modifications, which could affect the intake/carb choice, to some degree. Those 2V ports are larger than the ports on any Ford 351W head.

 

[rbohm]

i agree with the others, the cleveland engine is one that needs a lot of airflow capability to run hard. and unless the aftermarket intake was designed for the 4V heads, just get a set of 2V intake gaskets. as you noted you can tell the difference.

 

[clement]

we have been messing with a set of '71 4v heads for 2 seasons now. if the exhaust ports on the 2v are like the 4v they will also like a large header. at 10:1 compression with stock stroke we got the 4v motor to run high 10s on motor in a 3000lb car. this year we built a 408 with 13:1 comp and it has already gone 9s on the motor in the same car. and it wants more header.

 

[Walter Sparks]

wow you hitting in the 10s..thats moving out. I am not looking for a dragster, just a nice streetable car. MPG will be a concern but not a huge one. I have a highway gear , I am not sure what gear but I assume it is a highway gear. The rear may be posi, I can spin both tires in the dirt, but I am not sure. I may be interested if anyone has a set of 4v heads and a good intake for a decent deal. I am not sure what CAM I got, it is either stock or mild. I will post the brand/model of the intake and carb tomorrow.
Thanks

 

[clement]

that was with 4 barrel Cleveland heads, a restrictor intake and 750 carb at 358". we went with a larger intake and 1000 carb with the 408 using the same heads. the cam was also well over 250* at .050 lift. if your 2v motor is cammed right itll work great with the hwy gear and get decent mpg. the 4 barrel carb/intake on the 2 barrel heads will only effect it at wide open throttle. and expect it to run quite a bit better at WOT with the 4 barrel carb over the 2 barrel.

 

[Walter Sparks]

Thanks a lot. I guess there is no way to know what cam I got without removing it, but the car runs out pretty good so I am not really complaining. I have another parts car, it is a 73 Mach 1 fast back with complete drive train the vin says it was a 4v car but it has a 2v cleveland with a stock 2 barrel set up. I am getting the AC parts and dash and a few other parts off of it. I thought about trying to use the body off of it but it has some rust and needs quite a bit of body work. I was wondering if the 2 barrel set up would preform almost as good and get better MPG..but I will just stick with what I got and sell the extra 2 barrel motor. The pic in my avatar is actually my parts car.

 

[clement]

since on the 4 barrel, each venturi is smaller than the venturi size of the two barrel, and the fact that the 4 barrels run on the primaries at light throttle, its actually like running a smaller 2 barrel. even with a mechanical secondary and certainly with a vacuum secondary. so you should get better mpg with the 4 barrel when you stay out of it. but it will run better than the 2 barrel when you go wide open. at least that was the case when I swapped out the 500 cfm 2 barrel for a holley 600 on my 65 289 coupe twenty years ago when I was a teenager.

 

[Walter Sparks]

thanks..that makes sense.

 

[Hack]

You can find 4V heads for a good price all the time. You're going to want to find a pair locally though, because shipping is a killer. 351C heads are heavy. If you get that far into a Cleveland some things to know are that the stock valves are notorious for dropping the heads off them. You don't want to run stock valves.

The other thing is that closed chamber 4V heads are generally preferred over the open chambers. They can both work similarly, but the CC heads can be set up for better quench to run ~10.5 to 1 cr with 93 pump gas (obviously you need the right cam if you are pushing compression up to the limits of pump gas).

I remember as a kid reading that the fastest early Mustang through the quarter was the Boss 351. For being a bigger and heavier car with a smaller engine, that says a lot about the 351C 4V engine.

 

[Walter Sparks]

the boss 351 was for sure a fast car.. but I have mostly went with big blocks. I am sure a hopped up 429 would move this thing down the road. I just happen to know where an all original 1969 mercury marquis is that has a 429, the car supposedly has 29400 original miles on it and is drives out good. I could get the car reasonable but it may be a sin to part out an all original car like that. but that 429 would be bad news in my mustang.

 

[Walter Sparks]

Ok I got a
Weiand X-CELerator Intake Manifolds 7516

and a Summit 4 barrel vaccum secondary double pumper carb. I cannot find any numbers to tell if its a 750 or a 600.

 

[clement]

that should work pretty well.