yankees

Asking those who have actually tried putting 455 heads on a SBO 350. What are the exact/specific details in doing this? Gaskets, intake and exhaust manifolds, diff length pushrods, milling intake and head etc...?

J-(Chicago)

The dowel pins are different, so you will need to add one onto the deck of the block.
Small block intakes will bolt up fine, but the ports will be mismatched.

Head gasket is the same for both unless it's a 77 or later engine.

J-(Chicago)

The ebrock victor has enough material to match port. Not sure about the others, I've never ported those.

Stock pushrods will work fine.

J-(Chicago)

Hopefully the naysayers won't come out of the woodwork. I've been there and junked that, years ago.

The funniest, (or most shameful) combo that comes to mind, I picked up a 72 350 long block with th350 trans on craigslist for 50 bucks. It had 2 bad exhaust seats in the heads.

I didn't want to waste any money on it, in case it was a dud, so I bolted on a known good set of J heads and a 307 a5 intake.

Primed it, and it fired right up. Probably had a whopping 7.5:1 compression ratio, but it still ran fine. Compression test was between 127 and 130 in each cylinder. low, but consistently so at least.

s i 442

Thats a contradiction in terms!

Smitty275

You do not have to add a dowel to the block. You will have to ream the center dowel pin hole on the head to 5/16 though. Otherwise you normally have to run a Performer RPM or a Victor to get the intake to cover the ports in the head. Beyond that nothing really changes beside getting much better breathing capability which can lead to torque and HP .

yankees

Everyone thanks for the responses. Smitty any issues with the 2.07 intake valve and the 350 4.057 bore size? I'll just use your .011 head gaskets you sent me a couple of weeks ago.

J-(Chicago)

Bah, 50 bucks for 2 tungsten carbide hole saws and a cordless drill and they're good to go.

Don't get me wrong, they are pretty lame, but if they're not in scrap weight condition yet, they're fine for street beaters. and it sure beats an 800 dollar machine work bill if you just want to cruise.

Smitty275

No issues at all with the 2.072 intakes in a 350. I use the Milodon intake and exhaust. The exhaust gets turned down to 1.625. Makes for a great set up.

yankees

I may give this a shot with a flat top piston. With an 80cc head, .030 deck hgt and .011 head gasket thickness, this would put me at 9.09 to 1 compression.

Milling the heads 4cc to 76cc would increase the comp to 9.58 to 1

I would think either would be plenty sufficient for a bracket car.

oldsmobiledave

Where are you buying 0.011" thick head gaskets?

Smitty275

M&J ProFormance. I've had them available for several years now.

cutlassefi

Or you can use less cam on the exhaust side if you're stuck with the larger exhaust valve.

joe_padavano

Olds used these valves (and heads) on the long stroke 400, which has a 3.890" bore.

Smitty275

I turn the valve down because it will actually flow better at some points of lift and at no point of lift will it flow worse. The big valve does not always flow better. I also see no reason to remove material needlessly just in case somewhere down the road something gets damaged. That leaves meat to be able to go bigger if one must.