2v heads vs. 4v heads?

[1QuikMach]

I own a 351C with 4v heads. I also own a 351M motor that came the the factory 2v heads. Are they interchangeable with my 351C's? And if possible, is it worth it?

[thunderbolt]

My understanding is that yes the heads would interchange but you would then have problems with manifolds since the 351M was wider and the 4v heads have much larger intake ports, the 351M mainifold would have terrible port miss-match. I guess my question is why? The 351M is not exactly regarded as a good foundation for a proformance engine, where the only limitations to 351C's are minor oiling probems and thin wall casting (all of which effect the 351M if I am not mistaken).

[mustangman65_79]

I might be wrong, but didn't they fix the oiling probs with the 351M?

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66' Mustang 2bbl 289 coupe, stock.
79' Mustang soon to be a 302-selling-
89' Bronco 351w
AIRMEN FIRST CLASS
KASPAR T. HOWE

[mustangman65_79]

The reason why I say that is cause the 351M and the 400 use the same block, and the 400 is a good motor.

Hey, look, we all Registered in Oct-he he

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66' Mustang 2bbl 289 coupe, stock.
79' Mustang soon to be a 302-selling-
89' Bronco 351w
AIRMEN FIRST CLASS
KASPAR T. HOWE

[Idhomustang]

Ok,

I can hopefully enlighten all who have responded, maybe.
The 351C and the 351M and the 400M all share a common deck height. The differences is in the crankshaft ford made the mains smaller 351C size on the clevelands and the 351M is larger 3.0. The bore spacing is the same,so heads will interchange, Now there is a problem when going from 351 4V heads to 2V head you will need a new intake. Just as one of the others responded.
Performance, wise the 351c 2v heads for a street machine are a good way to go. Why you might ask would I say that, for a street machine you want a the smallest possible runner size with the highest volume of flow, why, this generates tremendous torque a street racers friend. They also will generate this power in a good operating range of under 6500 RPM.
Now on the other hand if you want to blow some doors off a Bowtie at the track, run the 351C 4V heads and spend the bucks for a good steel forged crank and light weight rods and spin it up to 9500 rpm, because that is were you will need to go to get the power and performance you are seeking.
For the money a good modified 351M or 351c 2V or 400M will produce upwards of 380-400 horses and the same or more in torque with off the shelf componets found at your local edelbrock dealer shelf, a good cam of 228-240 tops with a lift of 500-530 will make good power in a truck or car, and scare the bowties off.

Mac


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393,9.5" 351W,830 Holley,Victor Jr,Home made Cool Air Pan,
Pro Billet MSD,
MSD 6AL,
XE 284H Xtr-Com cam,
240-246 @.050,

[agawam]

I have a 302 with 351 cleveland 2v heads and a boss302 intake it runs ok but whoever built it didn't match the ports so as it sits it won't be competitive, so I plan to grind the ports to match, not a port job just a little funneling to make the flow smoother, so before I ruin a good set of heads, my question is can this be done ?

[Idhomustang]

Wow,

I didn't know those two manifolds would bolt together, a boss 302 manifold bolted to a set of 2V Cleveland heads ouch. I'm not sure that porting the 2v heads would do you any good. This miss match might actually work.

If it were me, I would lay or otherwise transfer the port shape of the 302 heads onto the 351 2v heads and make a real steep angle change to the 351 2v heads. Some what looking like a funnel for each port, so you are getting a good match port wise. I would not make the ports any bigger then what would be required to match the obvious mismatch.

They do this with windsor heads all the time to match the intake to the heads,this would allow a smoother transition which might just work.

Has anyone else done this, first I've heard of this, unfortunately they didn't make a 2v manifold for the Boss 302. let me know how this works or if you decided to do this, you have my interest peaked..

Mac.

[agawam]

That is basically what I intended, the intake ports sit to the rear of the head ports so I'm leaving the gasket on when I do it. I e mailed a guy in new zealand he says that ford/austrailia made a 302 cleveland till the mid 80s and 4v intakes are quite common and bolt on to american cleveland heads, the aussie heads are the same as 351c 2v. I might try to get him to send me one