302 marine engine.

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302 marine engine.

Post  dr's wife racing on June 1st 2016, 10:36 pm

Anybody know the good or bad about 302 marine engines. I have a chance to buy a low hr 302 ho marine engine. 190 hp I think. OMC brand.
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Re: 302 marine engine.

Post  dfree383 on June 1st 2016, 10:47 pm

Nothing special
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Re: 302 marine engine.

Post  dr's wife racing on June 2nd 2016, 8:07 am

It's cheap. It's nothing weird is it? Like runs backwards or any thing?
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Re: 302 marine engine.

Post  dfree383 on June 2nd 2016, 8:15 am

dr's wife racing wrote:It's cheap.  It's nothing weird is it?   Like runs backwards or any thing?  

I believe they did have reverse rotation ones, my dad had a pair in a house boat back in the 80's.

The reverse ones would have different cams and a few small parts.
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Re: 302 marine engine.

Post  maverick on June 2nd 2016, 4:22 pm

Possibly water pump differences depending on type of cooling system. I had a Chevy/Mercruiser deal once...the water pump ran backward. Otherwise, I rebuilt it with standard hotrod parts.
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Re: 302 marine engine.

Post  dr's wife racing on June 2nd 2016, 10:15 pm

I bought it today. As I said it was cheap. Came out of a master craft. I bought a package deal it came wit a 350 big bear 4 wheeler and other assorted parts.
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Re: 302 marine engine.

Post  rmcomprandy on June 17th 2016, 11:23 am

dfree383 wrote:Nothing special

SOME, 302 marine 4 barrel engines came with the M2 cylinder heads which certainly are special. A GT-40 intake port and early 302 passenger car exhaust port. The came on some 351W marine engines, also.

I have about 20 pair of new ones which have stainless valves and valve springs which are almost the same as the FRPP A50 springs.

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Re: 302 marine engine.

Post  dfree383 on June 17th 2016, 11:52 am

I wouldnt jump thru my butt for one or spend big money on one.......


Last edited by dfree383 on June 18th 2016, 8:53 am; edited 1 time in total
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Re: 302 marine engine.

Post  supervel45 on June 18th 2016, 3:36 am

rmcomprandy wrote:
dfree383 wrote:Nothing special

SOME, 302 marine 4 barrel engines came with the M2 cylinder heads which certainly are special. A GT-40 intake port and early 302 passenger car exhaust port. The came on some 351W marine engines, also.

I have about 20 pair of new ones which have stainless valves and valve springs which are almost the same as the FRPP A50 springs.

I have a 600 Vacuum Secondary Holley and the 1" cast iron spacer off one of those but a 351W. Totally different then a regular 600 and pretty nice too. We never built that engine and I am not sure what heads it had but, it was a Merc. Cruiser and you can get some pretty good deals on boat engines sometimes. SS factory valves would be sweet, to me at least.

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Re: 302 marine engine.

Post  dr's wife racing on June 19th 2016, 1:56 pm

rmcomprandy wrote:
dfree383 wrote:Nothing special

SOME, 302 marine 4 barrel engines came with the M2 cylinder heads which certainly are special. A GT-40 intake port and early 302 passenger car exhaust port. The came on some 351W marine engines, also.

I have about 20 pair of new ones which have stainless valves and valve springs which are almost the same as the FRPP A50 springs.
I gave 300 bucks for it complete. I'll check those heads out Randy. I was mainly buying it in hope the bottom end is standard. Ie .. Bore I have some real nice crank pistons and rods. For a standard bore it is already balanced.
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Re: 302 marine engine.

Post  dirt_worker on June 19th 2016, 2:16 pm

You didnt happent to get the marine exh manifolds w. it did you? Im in the process of repairing the engine in a boat i just picked  up that hadnt been winterized. (OMC 5.8 ) It cracked both exh manifolds, pushed out two core plugs, cracked the deck of the block and split the  powersteering cooler.

If you got them w. it id be interested if they're in decent shape.  Smile
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Re: 302 marine engine.

Post  rmcomprandy on June 19th 2016, 2:56 pm

dr's wife racing wrote:
I gave 300 bucks for it complete. I'll check those heads out Randy. I was mainly buying it in hope the bottom end is standard. Ie .. Bore I have some real nice crank pistons and rods. For a standard bore it is already balanced.

Those M2's are are "Bar" heads which have 2 bars on the casting ends. The GT-40's have 3 bars and the GT-40P heads have 4 bars.

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Re: 302 marine engine.

Post  dirt_worker on June 19th 2016, 3:14 pm

Are these the heads youre referring to Randy?
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Re: 302 marine engine.

Post  rmcomprandy on June 20th 2016, 12:21 am

dirt_worker wrote:Are these the heads youre referring to Randy?

That looks to be the M2 heads.

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Re: 302 marine engine.

Post  gt350hr on June 21st 2016, 2:05 pm

Randy ,
Are they preferred over 3 line or 4 line???? Any benefits?

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Re: 302 marine engine.

Post  dr's wife racing on June 21st 2016, 7:51 pm

dirt_worker wrote:You didnt happent to get the marine exh manifolds w. it did you? Im in the process of repairing the engine in a boat i just picked  up that hadnt been winterized. (OMC 5.8 ) It cracked both exh manifolds, pushed out two core plugs, cracked the deck of the block and split the  powersteering cooler.

If you got them w. it id be interested if they're in decent shape.  Smile
I have the exhaust manifolds. They look to be in nice shape. I told the guy I got it from I would bring them back. I don't think he is attached to them. He messs with boats some. I'll check and see if he has any thing paticular in mind for them.
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Re: 302 marine engine.

Post  rmcomprandy on June 21st 2016, 11:12 pm

gt350hr wrote:       Randy ,
         Are they preferred over 3 line or 4 line???? Any benefits?

NO ... but, they do have early 351W size stainless valves and are preferred over O.E.M. production  D_VE, E_VE or other regular production line heads.
3 line = GT-40 heads
4 line = GT-40P heads

The intake port is the same as the 3 line GT-40 port.
Grind the thermactor boss out of the exhaust port and they are really good factory heads. That boss takes-up so much of that port; it is longer, (as it is the entire length of the guide), and wider than most.

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Re: 302 marine engine.

Post  dirt_worker on June 23rd 2016, 12:14 am

My heads pictured above did have stainless valves but only on the exhaust side.
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Re: 302 marine engine.

Post  rmcomprandy on June 23rd 2016, 9:07 am

dirt_worker wrote:My heads pictured above did have stainless valves but only on the exhaust side.

The 20 pair on new M2 heads I have here are ALL stainless valves.

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Re: 302 marine engine.

Post  stanger68 on August 11th 2016, 7:42 pm

As a general rule marine blocks have a higher nickel content to resist corrosion. They are significantly sttonger, and some guys claim thicker walls on the Windsors. Mist of them do have reverse rotation. Simple fix swap camshaft and starter. And water pump if course.

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Re: 302 marine engine.

Post  rmcomprandy on August 11th 2016, 7:53 pm

stanger68 wrote:As a general rule marine blocks have a higher nickel content to resist corrosion. They are significantly sttonger, and some guys claim thicker walls on the Windsors. Mist of them do have reverse rotation. Simple fix swap camshaft and starter. And water pump if course.

Most of those 351W marine engines are NOT reverse rotation ... 2/3 of the production were regular rotation engines.
Ford Racing even offered then as crate motors a few years ago in 2 different stages.

1. Totally as manufactured with cast iron, 2 barrel, throttle body injection intake manifold = M-6007-J58

2. Same basic engine;
with Ford Racing "Performer RPM" type 2 plane intake manifold and Ford Racing polished aluminum valve covers - M-6007-S58

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