1978 Mercruiser 351 Swap For Auto Engine

[76GT150]

I have a 1976 searay srv220 and it has a mercruiser 351 233 motor in it and was wondering if it is possible to swap it out for an automotive engine if need be.The motor is locked up from previous owner and I dont know why. Im just wondering when I tear down the motor and it turns for the worst and can't rebuild can I swap an automotive engine in?

 

[Bondo]

Re: 1978 Mercruiser 351 Swap For Auto Engine

Ayuh,...

Depending on the Vintage of the donor,...
Either another 351w, or a 302w should bolt right in....

 

[76GT150]

Re: 1978 Mercruiser 351 Swap For Auto Engine

Risers and all should bolt on the same year engine?

 

[WizeOne]

Re: 1978 Mercruiser 351 Swap For Auto Engine

Risers and all should bolt on the same year engine?

Yes all would bolt up. Stick with a truck engine though, unless you want to switch cams. Also the auto/truck engines have steel freeze plugs. They will not hold up like the brass used in marine apps. Be sure to use your marine distrib, fuel pump, carb, water pump, alternator and probably your current oil pan.

I would stay away from a 302, there are too many peripherals that won't swap off your 351w.

 

[Haut Medoc]

Re: 1978 Mercruiser 351 Swap For Auto Engine

You will have an issue with the risers mating up with the y pipe if you go with a 302....
The 351 is slightly taller, & more importantly, a bit wider....
You will either need to get a y pipe from a model 888 or switch to center rise manifolds...
My advice is to stick with the 351....

 

[spudshaft]

Re: 1978 Mercruiser 351 Swap For Auto Engine

Stay with a 351 if you can. They aren't hard to find. A 351 is significantly taller than a 302. Both are great engines though.

 

[chuckd]

Re: 1978 Mercruiser 351 Swap For Auto Engine

I was told the same things," bolt right in", " swap motors?, childs play".NOT COMPLETLY TRUE. Depending which way you go, First of all theres the width thing, "hope your cowling isn't to tight. Then theres the oil pan, and oil pump w/ pick up tubes, then you might encounter the oil pump shaft and dist shaft being 2 different sizes... oh and on the oil pan you might noticed it may have the capacity part of the pan, "the deep part" is turned the wrong way to keep pump in oil under acceleration, although it still pumps it still gives an uneasy feeling. Now, you may need to SWAP cover for timing chain, you know the one that the WATER PUMP bolts to. You need to check this, otherwise you will have no place to bolt the ALTERNATOR, Then you will notice that you might need balancer, and pulley's.The dipstick will also need to be changed if you change timing cover. Trust me,.... you'll find other items not even listed here. Good luck w/ your BOLT RIGHT IN swap. lol plum wearin me out This article was written for informative purposes only any similiaraties to any persons are completly.......to be continued...

 

[coastalcruiser]

Re: 1978 Mercruiser 351 Swap For Auto Engine

I had 1974- 302 and pre alpha merc it was like an old car always breaking down. with countless issues because of the age of all the parts.
Wouldn't charge the battery (new alternator), the distributer wouldn't run points needed pertronix, the starter was worn out and it overheated etc i wasnt about to keep throwing money into it
I get great economy now starts everytime.
Imho if you guys like your boat but hate working on them, get a newer replacement, I have been having a great summer enjoying the 100f heat.
it takes one day to remove the old pos drive-engine so its your call.