DocSnickers

Looking to build up my 351 Cleveland. Right now its a 2v 2 bolt main. I want to put some 4v heads onto it. However I have heard it needs to be converted over to a 4 bolt main.

How easy would that be to do and would it be worth the money to do so? Or would it be better just to pick up a Cleveland that's already a 4 bolt? Hoping it's an easy job would really like to keep the original engine with the car.

TommyK

Switching heads has nothing to do with your main caps having two or four bolts. 4v heads will bolt on any 2 bolt cleveland block just fine. Therefore it is no more difficult than any other head swap. You will however need new exhaust manifolds/headers to match the 4V exhaust ports and an intake manifold for 4V heads as well.

I think it is worth it but some will disagree. BTW a 2 bolt cleveland block is plenty strong for any type of street build.

scott_m_mil

Above comments are correct. I will add that we use 351C's in our dirt track car. We've ran 2 bolt mains at 350+ horsepower (only allowed a 2bbl carb) at 6000 rpm without any issues. So don't feel that you must have a 4 bolt main.

69mach1377

The 4v heads are better at high rpms. Maybe just port and polish your 2v heads and put in a good matching cam?

1971mach1

Do you have a source on some 4v heads already? I have heard they are hard to get.
It all depend on what you want to build the car for (mild street, drag racing, high hp, high rpm).
The 2v heads do fine for lower rpm street use and even make a little more low-end torque than 4v. And you can get intakes for 4 barrel carbs that fit 2v heads. I would just keep the 2v heads for street, maybe a cam and port polish like 69 said, if you want a little more.

Starfury

The ports in 4V heads are absolutely massive, and too big for normal (or even enthusiastic) street driving with standard 351ci displacement. They actually make better power with port restrictors installed, but are still designed for high-rpm use and best suited for the track.

The stock 2V heads are just fine and can be cleaned up to flow really well without hurting low-end torque. You can also pick up a set of the new Edelbrock heads and matching intake that will bolt on and work well for a street car.

rmodel65

id get some austrailian 2v heads..they have closed combustion chambers so you dont have detonation problems like you do with the open chambers in the US 2v heads.. or buy some nice aftermaket heads..

69mach1377

Can you expand on these detonation problems you speak of?
With as many 2v engines out there, I'd think it would be common and I would have heard of it before.

1971mach1

In defense of the 4v (and I actually have one), even in stock form
it makes LOTs of power above 3500rpm. And 3-5K is normal RPM for enthusiastic street driving. It just needs GEARing to compensate for low end torque (just like Ford did with the Boss 351 (3.91 rear gear)).
It goes like a bat out of hell if you keep the revs up.

DocSnickers

1971mach1: Yes I already have the 4v heads, I picked them up off ebay last year they have been redone. They are just bare bone right now just need to buy all the parts for them. Picked both heads up for 600 and they are just beautiful, they were perfectly redone. They look like they have never been used, except for the date codes putting them at 72.

I would stick with the 2v heads if it was not for the fact that the engines been running with one 2v Cleveland head and one 400 block head. Not sure why have never figured it out.