302 or 351

hueypilot1960

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Jul 30, 2008
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I have a 1974 Slickcraft cutty with a mercruser that states 225HP on the valve cover, I have been told that it could be a 302 or a 351 for engine. Does anyone know how to tell the difference?
 
D

DJ

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Re: 302 or 351

It's a 351.

302's were rated in the 175-190 HP range.
 

WizeOne

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Mar 23, 2008
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2,097
Re: 302 or 351

It's a 351.

302's were rated in the 175-190 HP range.

Although it is likely a 351w, 302's w/ 4 bbls were rated at 225 hp. Measure the width of the intake mani. If it is 11 or so inches then it is a 351, if it is 9 some inches wide it is a 302.
 

chiefalen

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May 18, 2008
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3,598
Re: 302 or 351

Not in 1974. 302 i believe were 175-190hp. I think it changed in 77. I'm still pretty sure it's a 351. And i dont think it was 225 it was 220hp. I could be wrong here been wrong before.
 

MikDee

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Jun 6, 2007
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Re: 302 or 351

Although it is likely a 351w, 302's w/ 4 bbls were rated at 225 hp. Measure the width of the intake mani. If it is 11 or so inches then it is a 351, if it is 9 some inches wide it is a 302.

Not from what I recall, back around 1974,
I had an 18' Wellcraft Airslot with a 302/188hp Mercruiser with a 2bbl back then, and I made it a point to research, check, & see what the maximum horsepower a 4bbl would give me, it was only 215HP! or approx. 27hp more then the 188. This was all a futile attempt though, because I searched high, & low, to find a carb, & manifold, they were rarer then hens teeth! I wasn't gonna buy them new, too pricey! and I couldn't use an aftermarket aluminum manifold in salt water. I probably would have bought a new carb, if I'd have found a used manifold, but it wasn't to be.

If you had a 225hp Ford V8 back then, it was a 351 with a 2bbl!
 

Doug Redinger

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May 22, 2005
Messages
73
Re: 302 or 351

I have a 1973 Larson 186 bowrider with the mercruiser 888 which is a 302 Ford rated at 188 h.p. I have done quite a bit of reading on this motor as of late and I belive the 302 came in 2 different ratings. One was 188 h.p. the second was 225 h.p. The 351 came in 2 offerings one was 233 h.p. and the other was 255 h.p. This is from an old mercruiser manual.
 

fendersfender

Petty Officer 1st Class
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Mar 23, 2005
Messages
317
Re: 302 or 351

I had a '76 searay with a merc 888 (302 ford)...but, when i rebuilt this engine (cracked heads)....it was actually a 302 with 351 heads.....as far as i could tell, this was a original Mercruiser set-up?????????????
 

chiefalen

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May 18, 2008
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3,598
Re: 302 or 351

They are both the same block. Always was always will be haaaaaaaa.
 

a70eliminator

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Sep 9, 2007
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3,762
Re: 302 or 351

Not the same block 351 has 3" mains 302 mains are 2-3/4 oil pans don't interchange, also 351 has a much taller deck so intakes won't interchange either.
 

chiefalen

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May 18, 2008
Messages
3,598
Re: 302 or 351

Ok i think we got a bit off thread here.

We should start a new thread.
 
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