1985 350 Mercruiser and 1995 5.7L 350 Mercruiser block. Are they interchangeable?

Hello,
I recently started my 1985 25' SeaRay Sundancer after 4 years of storage. It started and ran smoothly, then I noticed a stream of water running off the block by the drain plug close to the starter. The block was cracked. I am a novice mechanically inclined person, I learned proper winterization unfortunately the hard way. It had a rebuilt 1985 350/260hp Mercruiser engine. Recently, I located a rebuilt 1995 5.7L 350 Mercruiser block with heads at a local machine shop. The question is can I replace my present block with this one and install my engine components (intake/exhaust manifolds, carburetor, water pump, starter, fuel pump, etc...) on it and are there any concerns I should be aware of. My goal is to complete the project myself over the spring/summer. I might add...my goal is to complete this project myself over the spring/summer months and I can use all the assistance I can get. Thanks.

If you don't mind, What does the machine shop want for a price for the motor?

If the price is a certain level a completely rebuilt motor of the exact same year +/- can be purchased easily.

Let us know what kind of money your are looking at spending.

Hi Jack,
Thanks for responding. The machine shop wants $900 for the complete block with the heads. Then I will have to complete the task, remove the old engine and install the new. My cash flow is limited these days (under employed and cash deprived) which is what prompted me to go this route. I had the engine rebuilt in 2006, had a marina order a complete block from Mercruiser and they transferred the other engine parts. Cost approximately $8000, with all the small hidden cost/labor.

I have not reached a dollar amount for spending...still exploring the rebuild feasibility. It is a Summer project to keep me busy during down time. This time I want more than just the engine for the cost of the repair...would prefer the machanical knowledge.

I purchased a 1987 Imperial v202 with a rebuilt 350 mercruiser for the engine/lower unit to install in the SeaRay last year. When I got to really examine the boat, it was in great shape with the exception of a few soft spots in the flooring. Needless to say...I have been using it every since.

I'm open to any ideas or help...greatly appreciated.
Thanks

Melvyn
New Haven, CT

Well one issue is the 1995 motor has a one piece rear main seal. The 1985 has a two piece rear main seal so I think you would need a different flywheel.

The Intake may be an issue also as the newer motor/heads may have a different intake bolt pattern.

Other than that I think all will be ok.

Manifolds and everything should be a direct swap. Only concern is if the accessories that bolt to the heads and motor that there is threaded holes where needed.......
Maybe some others will chime in with any known issues.......

First question... why only $900 for a complete 1995 5.7L long block?

Second question.... is this a Vortec 5.7L?

If Vortec, the intake must also be Vortec.

The 95 engine will definitely require the later flywheel.

All else should mate up and work.


.

I will address those questions this weekend. they did say a new fly wheel was required. I was also told that the intake bolt pattern maybe different also...still researching this project. Thanks.