Engine swap, 305 -->350 on a cobra

[Darcy]

I have a 350 block available, so I am researching the feasibility of swapping it out for my current (crappy) 305. This is in a 1986 SeaRay with a Cobra on it.

I need to check that the rear seal and drive system will mate up, and that the outdrive can handle the extra power.

I should be able to use the same heads, starter, exhaust manifolds, ignition, and fuel system, and freeze plugs off the old block.

I will need to install a new rotating assembly, and marine seals.

I will be using a pro to build up the engine, so no worries on assembly.

Anyplace I can research this further? What do you think of my conclusions?

Thanks!

 

[Yepblaze]

Re: Engine swap, 305 -->350 on a cobra

Have at it. I believe your camshaft choice should be either marine or RV/Pickup type so it doesn't suck water when shut down.


Use the search function as jobs like this have been covered a baZillion times by now.

 

[Bondo]

Re: Engine swap, 305 -->350 on a cobra

Ayuh,.... Probably Cheaper to buy a reman from a supplier,+ swap over your accessorial componants....

I should be able to use the same heads, starter, exhaust manifolds, ignition, and fuel system, and freeze plugs off the old block.

Nope,.. Those components won't be any good to you...
The heads will have much too small a combustion chambers,+ tiny valves...
And the brass core plugs are Throw-away items that just Ain't reused....

The drive will be Just Fine,.. Hopefully, you'll need a Bigger prop though...

1st thing to do is run the existing block's Casting #s to see which rear main seal it's got,...

 

[Darcy]

Re: Engine swap, 305 -->350 on a cobra

I'll put more time in on the search function. First shot didn't come up with anything, but I'll try some more!


Cam shaft will be a comp cam high energy marine.

Current heads have been ported and polished, with extra large valves and increased compression. Pistons will be matched accordingly.


The block is free, I just need to pay for the machining...


Thanks for the info! Off to search...