Marinizing a 350

[jaydubya999]

I currently have a 1990 Thompson Cutlass 195 with a 305 with a cracked block. I got a good deal on a 350 and want to Marinize it. What should I expect the cost to be?

[MMNet SEA]

Originally Posted by jaydubya999

I currently have a 1990 Thompson Cutlass 195 with a 305 with a cracked block. I got a good deal on a 350 and want to Marinize it. What should I expect the cost to be?

Is your existing 305 marinized ? If so, what components can still be utilized for the new 350 ?
The age of the Cutlass is given as 19 years, in which case an evaluation of the other parts of the system may be necessary to bring into the costing exercise.

[jaydubya999]

it is a 305 mercruiser the original that came with the boat. All the components are in good shape with the exception of a cracked exhaust manifold.

[MMNet SEA]

I currently have a 1990 Thompson Cutlass 195 with a 305 with a cracked block.

Originally Posted by jaydubya999

it is a 305 mercruiser the original that came with the boat. All the components are in good shape with the exception of a cracked exhaust manifold.

Hello there ,

little confused :- post 1 = cracked block
post 2 = cracked exhaust manifold

If 2. is correct, then it is possible to repair the manifold (cast iron can be welded if the whole manifold is heated up at the same time as welding the crack) Another alternative is to get another in good shape - new or used.

It was understood that you wish to exchange the 305 mercruiser with a 350 -
350 what ???

[tuantom]

If it came out of a truck, I'd get a marine carburetor and manifold (if necessary), repair or replace the exhaust manifold, and bolt the alternator, starter and distributor (not sure if this is 305/350 interchangable. It's not on small block Fords). The truck cam will be fine. The bell housing bolt pattern is the same; so it'll bolt up. You should also put in brass freeze plugs - though one engine I had did 25 years in Lake Michigan with steel freeze plugs (they were painted by the shop and we never realized); but they're cheap.

[Frosty]

Your 305 and your 350 is interchangable. For good manifold get a 4 wheel drive truck manifold dual plane with spreadbore with mechanical secondaries. vacuum secondaries can be converted by a small nut and bolt in the throttle slide. Edelbrock do the manifolds, there are others.

Do away with EGR and TCV you dont need them . Vacuum advance also discard.

[jaydubya999]

its a 1989 chevy 350 it was all set ( everything had been gone thru and checked) to be put in a car for racing but unfortunitly the fellow broe his neck and doesnt race any more. It has been in his garage for 5 years.

The previous owner of the mercruiser305 did not winterize it properly. At first I tried a jb weld that did hold up externily on the block, but after running clean a few times, the oil and water have mixed and everything is that milky gray mixture

[tuantom]

I'm sure the motor will be hearty enough, though with a race cam it may want to spin faster than you want. I would think that you want to keep the rpms under 5400 at the high end. If you can't track down the specs of the cam, you can always just put it in an see what happens. This is something that can be changed with the motor installed.

You might want to oil prime the motor before starting it.

[jaydubya999]

Thanks. I know the engine is basiclly stock, they didnt modify anything.

[MMNet SEA]

Hi JW,

Returning to your original question and the additional information you provided , including :-

" its a 1989 chevy 350 it was all set ( everything had been gone thru and checked) to be put in a car for racing. It has been in his garage for 5 years. "
In this case you have to ask the question:- for the period 1989 <> 2002 , what was this engine doing for 13 years?

I guess the answer to the original question, is like the answer given to the question "how long is a piece of string ?" Discounting what you paid for the 350 , costs are still going to be incurred for removing the old engine - recovering usable parts -
preparing the engine space for the new engine - installing new services etc.
Then start work on the 350 (which has been sitting unused for 5 years) establish exactly what is in this race car engine - is its format suitable for marine work? It might be worthwhile taking the rocker cover off , remove the spark plugs, add penetrating oil, crank the engine. Drain the engine oil - add flushing oil (10 SAE) Crank the engine. Drain the flushing oil - add new oil,
then put everything back together. Organize the engine to run on a bench - once you are happy with performance, you can measure up and work out what marinizing components will be required. At that point you will have a fix on what the whole conversion might cost. Website search shows a few
1990 Thompson Cutlass 195 with a 305's, for sale in the range 5 <> 6 K