OMC 350

[MarinerMarc]

I would like to know if another engine can replace an OMC 350. I was gifted a1984 tiara and engine wouldn’t turn but is otherwise in good condition . I suspected a seized engine. I attempted to manually turn engine at harmonic pulley which was unsuccessful. Also, when I removed spark plugs, water came out of one cylinder. I now also suspect a cracked head. I’ve read OMC went bankrupt years ago and I can’t get parts. My first ask is, could I replace OMC 350hp engine with chevy 350hp or other engine? I was also thinking of changing out engine and outdrive with possibly a Mercruiser. However, not sure of condition of OMC out drive and bellows hole is a concern because of it’s large cut out size and would need additional work to modify and close up transom for smaller standard stern drive. Worth the trouble and cost or not? If not, how does one get rid of boat?

 

[hugh g]

Sounds like a hole in the water. Before you even think about a repower make sure the transom, stringers, etc isn't rotted. You have a boat that is almost 40 years old.

 

[Scott Danforth]

I would like to know if another engine can replace an OMC 350. I was gifted a1984 tiara and engine wouldn’t turn but is otherwise in good condition . I suspected a seized engine. I attempted to manually turn engine at harmonic pulley which was unsuccessful. Also, when I removed spark plugs, water came out of one cylinder. I now also suspect a cracked head. I’ve read OMC went bankrupt years ago and I can’t get parts. My first ask is, could I replace OMC 350hp engine with chevy 350hp or other engine? I was also thinking of changing out engine and outdrive with possibly a Mercruiser. However, not sure of condition of OMC out drive and bellows hole is a concern because of it’s large cut out size and would need additional work to modify and close up transom for smaller standard stern drive. Worth the trouble and cost or not? If not, how does one get rid of boat?

any 1980-1985 GM 350 long block can replace your 1984 long block. OMC bought the long block from GM, then added their accessories, exhaust, induction and ignition.

they do not make a OMC stringer coupler for 1986 and newer 1-piece RMS blocks

yes, OMC means Obsolete Marine Company. the stringer drive was obsolete in 1985, the company stopped making drives in the mid 90's and went out of business in the late 90's

yes, fixing the transom hole for another drive would be work because you have to replace the transom and stringers. then again, your 38 year old boat will most likely require transom and stringer replacment from rot anyway.

only you can answer if its worth the $3000-$5000 it will cost you and the 1-2 years of weekend

to get rid of a boat, an electric chainsaw works. then you load the pieces in the back of your truck and take it to the dump. or you can tow the boat to the dump and for a fee they will take it off your trailer.

 

[Lou C]

I'd get out of that multi-year and thousands of dollars projcet any way that you can! Unless your goal is to learn how to rebuild a fiberglass boat from the bottom up and repower it as well. But it is years, and thousands of $$$$ even if you do a lot of the work yourself. If you want a boat to use, forget it!