A vs LA 318's

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Boze

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Hello to all,

I have a 1966 Chris-Craft cabin cruiser with two 318's, Marine version. One of them burned a piston so I was going to get two rebuilt long blocks and swap them out. But here's the question. Since this boat was built in 1966, I assume the engines to be 1965's or possibly very early 1966. I believe that means they are Chrysler's original "A" type blocks with the poly heads. The rebuilt long blocks available are the "LA" type and I believe they have the wedge heads.

What I am concerned about is bolting up the wet exhaust manifolds to wedge type heads. I have read on this forum that the LA engine was 5 inches narrower measured at the outside of the valve covers. My fear is there will be a big difference in the location of the exhaust surface plane and compared to an A type with the Poly heads. Could someone please confirm this?

Assuming the wedge heads are not going to work in this marine application, would it be possible to purchase short blocks and re-condition the poly heads I have? Will they work on an LA 318 block?

Thanks so much in advance.
 
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Just know that one of those engines is probably a reverse rotation engine.
 
Exhaust manifold s are not interchangeable. Are the valve covers held on by two bolts through the center of the top of the cover??? If so 318 poly not LA. I believe everything is available to get them rebuilt. There are several shops that can rebuild polys, I would be shocked if there wasn't one near you.
 
Thanks so much for your reply str12-340. Yes, the valve covers are just two bolts. I am in the Detroit area and should be able to find a good shop to do the machining. Thanks again.
 
So the last time I rebuilt a poly was many years ago for my 1964 Dodge Coronet 440, but I remembered that I got stuff from a company called Egge Obsolete, so I search for them and there they were! They still have oversized pistons for a poly and offer a complete rebuild kit. Their web site banner even shows a (Chris Craft?) wood deck boat so they may be familiar with the intricacies of marine V-8s. If you take this on please continue to post about the project. The 318 Polyspherical head engine is an under appreciated power plant. They were heavy compared to an LA motor (LA = Light A), but were pretty indestructible - kind of like a slant 6 of V-8 engines. They even make a new 4 bbl intake for them and you can still get finned aluminum valve covers.
 
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