View Full Version : Sea Ray repower

Kelly Harris
10-08-2006, 03:09 AM
"Looking to repower '74 Sea Ray SRV240, currently has Ford 351W in it, recently found water in oil, changed oil and filter ran it, then had water coming out if top of pan on starboard side. Pulled port head, found a burnt and cracked valve in 2nd cylinder from front of engine. Back two cylinders on port side full of water. What will I need to convert to small-block Chevy, 305/350, or possible 4.3 V-6. Have also considered converting to bracket and outboard/outboards. Any advice would be greatly appreciated.}}"

10-08-2006, 03:16 PM
"OMC or Mercruiser? They both used the Ford at that time. This may help determine what route is more viable. My first thought is repower with a new 5.7 Mercruiser. For the price of the 4.3, you might as well go with the 5.7.

If it is currently OMC, you're in for a project, and would be better with a reman 351. A bracket and O/B will be more expensive and this is money you will never recover on a 30+ year old boat.

Either way a new repower is going to cost more than the value of the boat, maybe you should look for a good used take-out or a remanufactured longblock.

Good luck

Kelly Harris
10-08-2006, 04:04 PM
"Thanks Rick. It currently has a MerCruiser system in it. Not real concerned with getting my money back out of it, was my fathers boat and greatly frankly is the perfect boat for what I use it for. I have both a 4.3 and 350 availible to use. The 4.3 is a brand new rebuild. Just curious what my best options would be. The boat has always been underpowered, hoping maybe the 350 would help, or possible twin outbaords with bracket. What is involved in going with the bracket and outboards?
Thanks for your help."

10-08-2006, 04:31 PM
"If it were mine, I would go with the 5.7. It will take some additional effort to switch over to the GM engine, but that will be the most cost effective and rewarding choice.

Switching to O/Bs will require filling the hole left by the removal of the I/O parts, plus reinforcing the transom to support the weight and torque of the outboards. You may not like what you see when you start poking around at that transom. The steering system will also have to be upgraded, hydraulic would be the best route for that fix.

A twin 4 cyl. O/B set-up with the bracket and steering will be $20K+. That is in addition to the transom work.

Even if you used a complete new 5.7 package, it should only cost about half of the O/B price.

That's my opinion, I'm sure others will disagree, but I hope it is helpful in making your decision."

Kelly Harris
10-08-2006, 04:50 PM
"Thanks again. Other than the engine, what will have to be swapped in order to go from the 351W to the Chevy 350?"

10-09-2006, 09:26 PM
"Kelly, Basically everything in front of the transom. You will need the GM coupler and bell housing. Mercruiser changed the mounting flanges on the bell hgousing since your engine was built. If you can't find an old style GM bell housing you will need to change the transom inner plate to the new style which will match the current bell style housing. Your shift cable linkage will also need to be updated.

Due to the age of your current parts I would suggest a complete engine assembly. A complete engine assembly will include all the parts mentioned, with the exception of the new inner plate.

Some glass work may be needed to get the height right for the front mounts. That's all I can think of off the top of my head.

Good luck"

Kelly Harris
10-10-2006, 04:28 PM
"Stupid questio, but my father had salvaged an older, late '70s I/O, that we took the outdrive off of for the Sea Ray. We kept all componets, not knowing when and if we could ever use them.It had a big 4 cylinder in it, by chance will it work for the 350 or 4.3. The 4.3 I have was built back to approximately 220hp.Again, any help will be greatly appreciated. What is your opinion, without actually seeing it, on the water in the cylinders I mentioned in my original message. Cracked heads or block. Is there anyway to check the exhaust manifolds for cracks? Thanks again."

10-10-2006, 04:50 PM
"If is is the 3.0L 4 cyl the bell housing will bolt up, but most likely it was a 3.7L, which will not do anything for you.

Regarding your original problem. Sure , with the proper work you can salvage the 351, but do you want to patch this thing back together or do you want to repair it so you will get many more good years out of it?

If I were considering repairing this engine, I would choose to install a remanufactured longblock instead. For about the cost of repairing this one you can buy a professionally remanufactured engine with a warranty. I would replace the tin and manifolds as well as all belts and hoses. I wouldn't even bother to test the old manifolds, I'd replace them along with the elbows."

Kelly Harris
10-10-2006, 05:15 PM
"Hey, thanks for all of your help. I will double check everything l have now. Just so Im not misunderstanding you, the bell housing on the 3.0 will work with the 350 or 4.3, correct? Thanks again, I am very grateful for the assistance."

10-10-2006, 05:30 PM
"Yes, all GM's have the same bolt pattern so the 3.0 bell housing will work. Also, if you do use the Ford engine there are ways to get more hp. There is a 5.0 H.O. which will bolt right in. With the right manifold and carb this guy will give you a lot more punch without a lot more bucks."

Kelly Harris
10-10-2006, 08:11 PM
"What will th eexhaust manifolds run me for the chevy, ball park?"

10-10-2006, 08:50 PM
You can order the Sierra system through this site. Total system should be around $800.00 with gaskets and hardware kits.