Marine engine rebuild??

[Herbykw]

Hello! New here and new to boating. I just purchased a 1977 Starfire with a OMC 302. I bought the boat pretty cheap an it is in decent shape for its age. Had an overheating problem, replaced the impeller(a bit of trial and error but fixed). Had a problem with the steering cable. Got it fixed. So everything was working fine. Had it out on the lake yesterday and it started clanking very loud from the port side of the engine. We immediately shut it down and were towed back. Mechanically my friends and I can take it apart and fix it. We work on cars frequently. My biggest question is what all is different about a marine engine vs street engine? I have read that the water pump is mechanically different. I would assume the engine components would be the same. Is there anything else I need to be aware of prior to going at this? Thanks!

 

[Howard Sterndrive]

OMC basically used truck engines.
I wouldn't worry about the water circulation pump in a marine engine rebuild unless it was in salt water, it's leaking, noisy, or the bearing feels rough by hand.

 

[user-name]

rebuild the omc would be much better choice.
FWIU OMC used industrial motors ( gensets)
to answer your ? street vs marine
cam
head gaskets
carb and fuel pump
starter. alternator
disty

On my the OMC 77 302 190 the water pump is the same as any torino

 

[Herbykw]

Thanks guys. I knew there couldn't be much difference. What would be different about the cam? As far as I know the boat hasn't been in salt water. The water pump seems to be in good working order. Smooth and quiet.

 

[jester31]

The marine water pump I went to replace on my 74' 888/188hp 302 had a stainless back cover, and a different impeller then a car pump, but new at the time from Mercruiser in the 80's it was $325, too rich for my blood! So, I used a $30 car pump, figuring I could replace it every year for the next 10, and still be ahead of the game! By the way, these 302's were designed like, and used 351 Windsor parts.

 

[user-name]

. What would be different about the cam? .

marine cams are cut way different than street cams.

Basicly
stock street cams are made for the changing of rpms the way street is. speed up slow down up hill down hill . ETC ETC and lower RPMs

a marine cam is cut for constant non changing of the rpms and higher RPMs

basicly a boat is always going uphill pulling a heavy load.

 

[bruceb58]

Use a marine water pump even in fresh water. The seal/bearing is way different. An auto water pump is fine if you use closed cooling and the water pump is running in anti freeze.

 

[user-name]

Use a marine water pump even in fresh water. The seal/bearing is way different. An auto water pump is fine if you use closed cooling and the water pump is running in anti freeze.

I 2nd that.

I forget not all boats are closed water cooled. Mine is.

 

[Howard Sterndrive]

What would be different about the cam?

you can probably reuse yours, but if you do, keep track of where the lifters lived and put them back in the same bores, or get new lifters.

the cam OMC used in that motor is Ford part number D3OZ-6250-A.
Like most Ford marine motors, that cam changes the firing order of the 302 to that of a 351W which has always confused a lot of people with those motors, because often the firing order on the intake is not what is required on the engine. The grind is just automotive. That cam was used in pickup trucks, Lincolns and Mustangs some years with 5.8 or the 5.0HO motors.

 

[user-name]

What 302 do you have?
175hp firing order 1 5 4 2 6 3 7 8 Has the 302 cam
190hp firing order 1 3 7 2 6 5 4 8 Has the 351 cam & heads

 

[Herbykw]

Thank you. You guys are great. Would take me forever to find some of this info. The engine I have says 190 on the valve covers. An a sticker that shows the firing order in the valve cover also

 

[Herbykw]

We'll pulls the motor and found the problem. On the plus side, I do NOT have to rebuild. On the downside, I DO have to replace. A piston rod broke and took chunk out of the crank, block, piston dented the oil pan and metal parts everywhere. sad day.