? for Dennis Moore and Rexone.

[MANIC MECHANIC]

I have a four bolt main, early seventies 454,
rectangular intake port Dport ex. port head.
Don't know a lot a bout heads. what is the differance between
open chamber and closed chamber heads, how do I determine what I have?
For this motor, (with the few specs that I have given) what would be the hot setup (as far as the motor goes :Cam, intake, carb, ETC) for a recreational jetboat with a light layup in the 19' range with a good setup(by Rick Hendricks in the 70's) and a detailed SS "B" cut impeller?
I would appreciate any info.
Tim

[Rexone]

Tim,
Looking at the chamber of the head if it is just about perfectly oval in shape that would be closed chamber. If it is opened up on one side it will be what's called open chamber. Many variants of each exist. Check here by part number for exactly what you have. (http://www.mortec.com/bbc.htm)
Below is an example of a fairly typical "open chamber" shape. Notice the open area around the spark plug. Closed chamber heads don't look like this, that area is not open and the chamber is much smaller.
While I could stab around at making recommendations for the ideal engine and come up close I'll refer to Dennis or the other engine gurus here on that since they do it day in and day out and can probably give you the part numbers you need to look for and a more meaningful and exact answer.

[Rexone]

Typical open chamber design...

[Dennis Moore]

Use a dual plane Edelbrock Performer RPM intake manifold and an Edelbrock 750 Marine Square Bore carburetor.
The Edelbrock Torker camshaft, lifters and valve springs will work great.
Install a Pertronix II breakerless conversion into a Mallory marine distributor with 10 degrees timing at idle and 34 degrees full ignition timing at 3400 rpm.
Center riser exhaust manifolds will help.
For more information about closed and open chamber heads check out the latest heads in the Edelbrock catalog.
Dennis Moore