2v to 4v

[73 XR-7]

i have a 1971 351 Cleavland that i am putting in my 1973 mercury cougar and i want to swap the old 2v manifold and carb for a 4v manifold and carb i already have the carb and manifold but i am wondering if i have to put in a higher lift cam or anything like that

[MrPbody]

73,

Changing to the 4 bbl. carb is a moot point without changing cams. I would use at least a "mild" performance cam to make the swap worthwhile.

Important question: Is the 4-bbl. intake you have a Ford factory intake, or an aftermarket designed for use on the 2-bbl. heads? The latter is the correct approach. The former is not. The port opennings on the 4-bbl. (factory) stuff is WAY too big for the 2-bbl. heads.

Jim

[73 XR-7]

the manifold is a edelbrock it not the original 4v off of a 351 Cleveland

[73 XR-7]

i also heard that the 1971 cleveland has a higher lift cam stock is this true because i am on a tight budget i put all my money in buying the car and cant really afford to be putting out much more money then i already have

[MrPbody]

Okay, again, is it an intake to convert the 2-bbl. heads or is it a "4-bbl. head" intake?

If it's "Performer", it SHOULD be the correct one. Match the intake gasket for the 2-bbl. head up to the flange and be sure the ports are about that size.

Jim

[73 XR-7]

it is to convert the 2bbl heads to a 4bbl and everything matches up but how much power would i lose by leaving the stock cam in

[MrPbody]

Using the 2-bbl. cam simply doesn't allow the 4-bbl. carb to "do its job" properly. 4-bbl. "C" engines DID have a "larger" cam than 2-bbl. engines.

Jim

[73 XR-7]

alright then i have the engine apart right now and my uncle and i are going to be putting a mild lift cam not sure how much more lift but he knows a lot about engines so i dont think i will have any problems thanks for all your help by the way do you know the number for the gasket for the edelbrock intake switching from2v to 4v on the 2v heads

[MrPbody]

Yup. Felpro Performance part no. 1240. Anytime the word "Performance" is behind "Felpro", one must insist to the parts person, NOT in the "regular" Felpro catelog. "Performance" catelog ONLY.

Highly recommend Comp Xtreme Energy cams. For a modern engine build, WAY past the old grinds, and yes, better than Ford Motorsports grinds. For the Cleveland, some grinds must be "custom" ground. Not a big deal, just a little waiting (about 4-5 days).

Jim

[73 XR-7]

ok thanks for everything i will let you know how it runs when it is all finished and if i have any more questions ill just ask you have been a big help thank you

Nigel

[MrPbody]

Nigel,

Glad to help! That's why I'm here...

Best of luck, and above all, HAVE FUN! This IS a "hobby", so always keep that in your mind and none of the obstacles you encounter will be serious.

You can e-mail me directly if you wish.

[email protected]

Jim

[73 XR-7]

thanks Jim all of this really helps im only 17 and i love to do all of this stuff the worst thing for me is the money but like you say it is a hobby i plan to have the car done in April oh and thanks for you email if i have any questions i will certainly ask