Before I open my wallet

[mlaymance]

My boat currently has an OMC 185hp(305) engine(inboard with a BW velvet drive.

I am planning on replacing the engine withing the next couple of months. Before I do this I have several questions that the experienced hopefully can help with, so here goes...

1. I want to change to a GM 350 (5.7). I will be purchasing a long block from a reputible rebuilder (suggestions appreciated). I have been told that ALL parts from the 305 will bolt to the 350 such as water pumps, intake, distributor, oil pan, etc. Is this true?

2. The engine is a 1979 and has a 2 piece oil seal. I understand that the difference is the crank bolt pattern and a later model (post 1979) will not bolt up to my velvet drive. Is this true?

3. My engine has a port side Oil pan.(the dipstick is on the port side). Until today I didn't realize that there was a difference and assumed that that was determined by the oil pan alone. Is there really any difference between the engines that would cause this to be an issue?

4. What would be the advantage to replacing the stock manifold with a manifold of Higher performance in this case? This boat is used mostly for fishing and cruising, but occasionally we pull a tube or skiier.

5. I will be replacing the "log style" rear exit exhaust manifolds with new. These are quite expensive compared to the VP or mercruiser manifolds. Is it possible to change these manifolds to the VP (or mercruiser) style manifolds without damage to my new engine?

Thanks again for your opinions and Info.

mlaymance

 

[mlaymance]

Re: Before I open my wallet

I guess noone knows???

 

[Fishermark]

Re: Before I open my wallet

I don't know anything about Velvet drives, but yes, the externals from the 305 will bolt onto the 350. Keep it simple and get an older 350 with a two piece rear main.

 

[Howard Sterndrive]

Re: Before I open my wallet

I will be purchasing a long block from a reputible rebuilder (suggestions appreciated).

for around the same price as rebuilt, you can buy brand new.
I would recommend the GM parts 290/350 Crate engine. Brand new 4 bolt main motor with 2 pc rear main. The specs are the same as the old 260HP mercruiser/OMC of the 70's and 80's - including the cam
All you need to do is pop $14 worth of brass core plugs in the block.

I think you'll find it has the right pan on it, but not sure what OMC used for a pan on the inboards.- you might have to swap your pan on to any replacement engine

long block does not typically come with a pan. Crate does.

 

[cr2k]

Re: Before I open my wallet

Changing your manifolds won't hurt your engine, you just need to be sure they will connect to the Y pipe, etc.

 

[mlaymance]

Re: Before I open my wallet

Guys Thanks for the Info.

I have read different stories regarding rebuilt Vs. Crate.

Crate engines are new, but Others say that the rebuilt engine blocks have been seasoned and that makes for better sealing faces for the gaskets.

Money is somewhat of a concern, and hopefully I will not have the boat for another 5 years, as I would like to have something bigger.

The old 305 block is just tired, low compression, with noticible blowby, and not as dependable as it used to be. The boat came with the 350 as an option, so there shouldn't be any concern regarding horsepower.

It does require a block with a 2 piece rear seal in order to mate to the velvet drive.

One thing that I hadn't thought of before is will it need to be re-propped for the horsepower gain? (maybe a post for another thread).

I'm glad I can convert the manifolds to mercruiser. That really helps in the money section, allowing me to go to a new breakerless ignition instead of using the current mallory point type.

Thanks again for all the info guys!!!

Michael