383 build using log exhaust

BearlyFunctioning

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I'm doing a Merc 383 build for a 1982 24' express cruiser.

I have two items possibly limiting my build
1. Still going to use log style manifolds and through hub exhaust.
2. Rear deck (engine is under the floor) that is only 4" above top of carb (without flame arrestor) with the stock intake manifold.

This is going to be a ground up build, budget is some-what of a concern, hence the log manifolds stay.

My engine builder (who is going to dyno break-in and tune the engine) is telling me there is not much more to gain past vortec heads or even aiming for excellent quench by going to aftermarket alum heads with a larger chamber. How true are his statements ?
 
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alldodge

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Guessing your in fresh water, and agree don't see any reason for aluminum heads. You do want to get your quench close to .040 and keep compression down so you can run 87 octane.


If your manifolds are 1982 old, and not just newer old log manifolds, I would suggest replacing them. No since taking a chance with a new motor and old mans
 

alldodge

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OK, you can get better exhaust flow with centers, but you should be in better shape
 

Bondo

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Ayuh,.... I agree with AD, 'n yer motor builder,....

Shoot for a tight quench, 'n enjoy the torque,....
 

Scott Danforth

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no benefit with aluminum heads in a typical boat. ditch the logs for center riser exhaust and free up some exhaust flow.

piston choice will have most effect on performance. make sure you use an LCQ style piston with the vortec heads.
 

Scott Danforth

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forgot to mention. SCAT kits are better finished and require less work than Eagle kits (both are chinese imports)
 
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