repowering my 3.8 to 4.3 gm

[mrdimuzio]

I have recently purchased a 1984 19' mach 1 with a motor that was not properly winterized. It has sustained a severly cracked exhaust manifold,and the block has 2, possibly more, freeze out plugs popped & water in the oil. Since one of the plugs is behind the engine mount I assume I have to pull the motor & that it is need of replacement or rebuild. Can I replace this with a 4.3 from the 3.8 ? If I buy new exhaust manifolds with a 4.3 will they line up with the heat risers and ehhaust piping ? what other things will I need to be aware of ? Also can I drop this in against the existing outdrive or is there some sort of alignment process I need to do, ifso how do you do this ? sorry so windy but your input is greatly appreciated... email is ddimuzio_5223@fuse.net<br /><br />Thanks,<br />Dan

 

[KaGee]

Re: repowering my 3.8 to 4.3 gm

Dan:<br />Welcome to the Boards!<br />I had the exact same scenario.<br />I put a remanned 3.8L long block back in and found a set of used exhaust manifolds at a local boat yard to get by.<br /><br />The 4.3 block will bolt up to the bellhousing and engine mounts, but you'll have to find one complete as the intake manifold & valve covers are different. Not sure, but oil pan may be differnt too.<br /><br />Moore Performance makes an aftermarket exhaust manifold and center riser that you will have to do some custom fitting with hose and elbo to rig back up to the intermediate housing exhaust port.<br /><br />Hope this is helpful.<br />Keith

 

[mrdimuzio]

Re: repowering my 3.8 to 4.3 gm

Thanks. Is there anything special about a boat intake manifold or can I buy an automotive aftermarket intake manifold like an edelbrock ?<br />I also might be able to get my hands on a rebuilt 350 V8 truck motor for short money. Are the engine mounts in the same location in relation to the flywheel and width as the V6 ? I may need to cut a notch into the floor joist in front of the engine to allow for the extra length. Provided I use the marine accessories, (water pump, alt, starter) and change freeze out plugs to SS or Brass, can I use the 350 ? has anyone done this that could tell me the yeah's and neigh's. Thanks again... Dan

 

[KaGee]

Re: repowering my 3.8 to 4.3 gm

Do you currently have Selectrim? If so, the hydralic hoses have to be lengthened for a 350 block (it's longer).<br /><br />Intake is stock., you could use your carb, but jetting may be different.