OMC 302 bad block

**** I have been*a fan of this forum*for years, and now need your valuable help again.* I will give as much info as I can so please bear with me...I have just obtained a fresh water 19' 1994 Four winds 302 cobra (2 bbl) for almost free. It has many positives.* The boat has an excellent trailer, excellent*hull,*solid stringers, fair*interior,*very low hours (260), the*manifolds, risers, alt, 2 bbl carb, etc look almost factory*new, and the omc out drive is in excellent*shape and has no issues.*It started and ran fine on the hose in the driveway for 10 minutes*with no issues, so off to the lake we went, *it was soon was apparent when the*steam started coming out the pcv vents that it either had a bad head gasket or a cracked block..* Pulled the plugs, two on left side had water,* pulled the head, it has a cracked block..** bummer..**Here is where i need your expert help again,* I am a chevy man and know a whole lot about rebuilding gm's,* but not a lot*about fords..*** I don't know the different types of years*of ford 302 blocks out there that will fit with bolt patterns of heads, intakes, flywheel patterns, *etc....*
* Can you please get me headed in the right direction...
Money is a huge object here, (wife has tight purse strings).....* I would love to*get a marine*crate engine, but that will not happen...

Can you please get me headed in the right direction with what year/style 302*blocks fit this?

thank you again for all of your help.

The 302 block is kind of like the small block chevy there are not a lot of differences through the years. any 80's or early 90's 302 engine should work for you. If I remember right the fuel pump is in the front timing cover on that engine. there is a difference in firing orders in the 302's it is 15426378 on non HO engines and 13726548 on the HO engine. either engine will work just make sure to use the marine cam in it and the firing order will stay the same as what it already is

Go to an automotive Ford enthusiast forum. These guys know their 335 series Ford engines.
Just as with the GM SBC, some castings, casting years and casting places of origin, are better than others.
These guys will know where to direct you.

Just don't build to the automotive specs..... in this arena, steer clear of these forum build techniques.

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With the low hours, what you can do is take all the marine stuff like the forged crank, rods and pistons as well as the marine cam and swap them over to a regular old truck 302. The car versions are not made with the same nodular iron as the truck blocks, so don't even bother. Just find one of the ten gazillion f150 or f250 pickup trucks from 86-93 in a wrecking yard, have the block tanked and magnafluxed, honed if needed and put it all back together. Maybe cost you a few hundred plus all your labor, and a (Sierra 18-4385 ~$225) gasket set from our hosts is all you need.

Sheesh! Don't go back together without cleaning up the bores and new pistons/rings.

You can have the cylinders bored for around $150 to $200.
New piston set, about $120-150.
You'll be using new bearings and piston rings anyway!

The 5.0L and 5.8L Ford uses a wedge shape as part of the combustion chamber, similar to the SBC.
With this design, you can create a squish zone or Quench Effect combustion chamber if/when the correct piston profile is used.
Steer clear of the full dished pistons, create a squish or quench by using a more suitable piston profile, keep the static C/R where it should be for Marine use....., and give this engine some low end torque.

See this thread re; the SBC (starting at post #9), and see if you can incorporate some of the same build techniques.


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Ford marine pistons are as flat on top as your first girlfriend. If one is lucky enough to find a block that hasn't been bored and the cylinder walls aren't too bad then you can get away with using the marine pistons from the dead engine. New Ford marine pistons for 302 seem to be NLA. You can get similar replacements for about 90-120 EACH.

Just curious why you'd try to resurrect this engine. For what you are going to put out in time and trouble you could probably find two or three good used donor Chevy marine engines. You can slide a Mercruiser right into place, the only thing I think you'd have to change is the bellhousing (to mate with the transom fitting) and the exhaust manifolds, but I don't really think you need to change those. The bellhousing you have may actually be OK cz they made a sorta universal fit that will go on either Ford or Chevy. I used one off a OMC Cobra Chevy on my Ford (!). The coupler from the Mercruiser will fit no problem.
Yup. Oh, yeah, you'll need the Chevy throttle bracket for Cobra. I think those are on EBay for cheap.

Thank you for the great info. The engine specs for the boat says 5.0 HO. I was hoping it had a 4 bbl, but had not seen many 4 bbls on fords. Yes the pistons are flat as my first girlfriend,, 35 years ago,,, (i was 10 then).,, View attachment 5426 I will try to find a decent 5.0 from a truck and change over everything from crank to cam. I am in NC and we still have 2 months of boating left before winterization. I had not thought of the chevy change over, just need to find the chevy manifolds, maybe sell the ford ones,,, they look brand new... I can do the throttle change over, no issues, and have done the shift cables adjustments and memorized the directions you guys put out on omc shifter adjustments until i can recite it in my sleep... great info... I have a question on the firing order with the HO vs regular -- different cam and crank but same block? yes the fuel pump is on the front right (looking at it from the front) timing cover... another quick question.. the 351,, is that the windsor model., would it bolt up...just in case I found one,,.. had an old grand tourino one time with a 351 in it,,, loved it,,, but that was a long time ago... plenty of room in the engine bay area,,, would always love a few more horses,, would the 5.0 omc unit handle it... thank you again for your time, advice, and all your help for us guys that just can pull out $100 dollars bills out of the wallets and buy new,,, this forum is fantastic for us DIY'ers....

last line,, not "can",,,, but "can't" pull $100 dollar bills out of the wallet to buy new.....
thank you again for your help....

In the Windsor line, the 5.8L and 5.0L use the same rear engine flange. So if you are asking if a 5.8L will bolt up to the 5.0L your flywheel cover, the answer is yes! However, only a few of your 5.0L parts will work on the 5.8L.

If you are asking about the Cleveland 5.8L, this is apples/oranges.


Also, the GM SBC is not a candidate for the 5.0L Ford flywheel cover. The pattern is completely different.
Perhaps O2batsea may be thinking of Borg Warner components, but I'm not aware that this year model drive ever used Borg Warner components.

Now, here's the other thing that I did not mention earlier.
Your 1994 Four winds should actually be a Volvo Penta cone clutch drive.
You may see the OMC logo on several parts, and perhaps OMC information, but by 1994 the Volvo Penta OMC purchase agreement was in the works by then. The drive appearance is somewhat similar to the OMC Cobra, in certain respects... but this is all Volvo Penta cone clutch design.

So yes..... this drive will be suitable for either the 5.0L or the 5.8L engine.


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If you want a Chevy flavored Cobra bell housing I think I may still have one. I know for a fact that the Cobra bell housing from a Chevy will fit a Ford cz that's what's on my boat. Therefore a Ford Cobra bell housing will fit a Chevy. They put a bunch of holes in them! One other strong argument for changing to Chevy is the Ford marine parts are hard to find, especially the couplers. (Much to my regret being a Ford person) Try to find a marine 4 barrel intake for a 302! Ain't gonna happen! Arrrr! Anyway...
One other thing that may help you in the future: marine engines are referenced from the rear looking forward. So a starboard engine will be on your right and a port engine on your left as you stand at the back of the boat looking forward. Rotation is also from the rear looking forward. Standard rotation is clockwise, reverse rotation counter clockwise. Generally speaking the starboard engine as well as singles will be standard rotation. Port will be reverse rotation. Same with propellers (this is to counteract the "push" of the propeller) Therefore you must forget about right and left when referring to the engine, the boat or which side your drunk brother in law fell over.
So, the fuel pump is on the port side on a Ford....
HO vs regular old Ford: Everything is exactly the same on all the engines. Crank, cam, pistons, everything. What makes an HO an HO is the fact that some smart cookie discovered that by changing the firing order you get more horsepower. That's it. Big whoop.
Marine cam vs regular car cam: Marine engines are always going "uphill". That is, the faster you want to go the more load and they never ever coast. The cam is set up to deliver a gradual curve of power all the way thru the RPMs. Don't try to use a car cam in a boat, it doesn't work.

I am sorry but I have to disagree I found out the hard way that there is more of a difference between the 5.0 and the 5.0 HO than just the firing order. I wired a 5.0 non ho the way it was suppose to be after an engine rebuild and I had a dead miss on 4 cylinders. I found out that the machine shop that did the work for me had put in an HO cam when I rewired the motor to the HO firing order my miss was gone

wmlaks said:

I am sorry but I have to disagree I found out the hard way that there is more of a difference between the 5.0 and the 5.0 HO than just the firing order. I wired a 5.0 non ho the way it was suppose to be after an engine rebuild and I had a dead miss on 4 cylinders. I found out that the machine shop that did the work for me had put in an HO cam when I rewired the motor to the HO firing order my miss was gone

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Car engine or boat engine? Car engine, yes. Boat engine...only one cam grind for HO or Normal, at least from Ford.

As I said in my first post..... visit a Ford enthusiast on line forum, and ask these questions.
If you are transfering your existing crankshaft and camshaft, aren't some of these questions a moot point????


O2batsea,
The 5.0L and 5.7L SBC rear engine flange, and the 5.0L and 5.8L Ford rear engine flange are NOT the same.
You cannot swap flywheel covers (what you're calling a "bell housing") between these two engines.
It simply won't work!

GM SBC rear engine flange:
The two right and left, lower and outer, machined holes are vertical over one another.
The top machined hole is at center.
Note the total of 7 machined holes.




Ford 5.0L and 5.8L rear engine flange:
The two right and left, lower and outer, machined holes are NOT vertical over one another.
There are two top machined holes, and they are NOT centered.
Note the total of 6 machined holes.

O2batsea,
The 5.0L and 5.7L SBC rear engine flange, and the 5.0L and 5.8L Ford rear engine flange are NOT the same.
You cannot swap flywheel covers (what you're calling a "bell housing") between these two engines.
It simply won't work!

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You can say that all day long but the fact remains that the flywheel cover for OMC Cobra, at least the two that I have, are indeed interchangeable between Ford and Chevy. There are holes in it to accommodate both bolt patterns. I'd take a picture but it's in the boat! I am well aware of the different rear bolt pattern. But let's not hijack the man's thread.

O2batsea, sorry that I sounded so stern on that. For a short while, I thought you must have been very mistaken between the Ford and Chevy rear flanges. Had I understood you to say that these F/C's used an ambidextrous bolt pattern, I may not have questioned this.

Apparently I've seen only the engine specific/proprietary flywheel covers, such as the GM, for example.





Is this what you are referring to? If so, then I stand corrected!
My apologies, and thanks for the lesson!





The remaining question would be if the OP's 1994 flywheel cover is similar to the actual OMC design.



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Yup, that's the puppy. Now back to the regularly scheduled program...

Thank you again everyone for all of your help. I am on the search for a good 302 truck block that I can change over parts. Most of what I am finding so far is soouped up mustang 5.0's and that is not what I want...
I need one more question,.,,, must I go with marine head gaskets? they are sooooo expensive,,, I understand the rules on marine starters, alts, etc and and will abide by them. I plan on using all of my original bolts ons... but I am in fresh water only.
. Thank you all again for all your your help.

Here's the dealio. When your car breaks down you can either get out and walk or call someone to help. When your boat breaks down you drift. Maybe for quite a long time. Maybe into a channel, maybe into open water. Maybe your celly works, maybe not. Do you really want to become a hunk of driftwood? Do you really want to be towed in? Pay the man for the marine head gaskets.

rhays, whether fresh river/lake water... or even ocean water..... it makes little difference when it comes to the cylinder head gaskets.
Unless the engine is closed system cooled, the PH balance of river/lake water will eventually cause head gasket failure.

Since you did say that the original block was cracked, I'll assume that this engine was raw water cooled.
If so, and if it remains raw water cooled, I'd have to say yes..... you'd best stay with the Marine gasket set.

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Got it... I will go with the Marine Gaskets..... I was hoping they only had to be used for salt water. I really appreciate everyone's help and will go with what you recommend. Your advice is years of knowledge that I dont have and that I why I love this site....
thank you again....

You are beginning to understand what they mean when they say a boat is a hole in the water, surrounded by fiberglass, into which you throw money.

o2batsea said:

You are beginning to understand what they mean when they say a boat is a hole in the water, surrounded by fiberglass, into which you throw money.

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Man, isn't that the truth?
Boat ownership requires a certain attitude and a good budget.
We'll dang near always be a bit upside down. Trust me.... I know this one very well.
We just use it up in the form of enjoyment.... much like any other hobby.

I'd not recommend doing this..... but we can add up our total cost, then divide this by the number of hours of enjoyment, and there's our cost per hour.

If you are very brave, you can subtract your number of frusting hours from this.
That's the number that you may NOT want to look at!

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OK,,, now i need your help again.... i found an 87 5.0 block out of a f-150 with a carb, flat cam lifters, etc that matched,,, but it had water in it,, so it went to the junk yard,,, i just bought a 1995 mustang 5.0 HO that looked identical on the outside to my 94 OMC block... took it apart, side by side, it was a roller block... I switched the cams out , as the 95 mustang was a roller cam vs my regular old style cam... ,, but here is my question...when i pulled the heads,,, the pistons are both the same, flat with just valve grooves for both motors,,, a boat engine vs a mustang 5.0, i expected it to be a dished or domed top piston, but it is identical to the marine piston,, and i mean really identical to the marine piston... .it is an alluminum piston,, mine is a 94 omc boat block with reg cam and flat tappet lifters and carb, the 95 mustang had a roller cam and roller heads, ( the heads from a roller cam can not be used with a reg cam-- different spring rates, as i am told on the ford websites... ) ===== I really dont have any issues with any of this so far,,, I was prepared to change out the cam, pistons, and the crank,,, but so far,, the pistons are the same.... do i nead to change out the crank.. the mustangs 5.0 is rated at 240 horse,,, the 94 omc is rated at 190.....,, i understood the omc boat engine to have a forged crank,, but if the mustang 5.0 is rated higer,, do i need to change it out?
As I have said before, I will go by your expertise,,, opinions, and general knowledge,,,, but if i dont have to change a crank,, that would save alot of money... thank you again four your help.....

Then you will have water reversion problems. Water being sucked into the valves. You need the correct grind. The old one is shot ?

OK,,, now i need your help again.... i found an 87 5.0 block out of a f-150 with a carb, flat cam lifters, etc that matched,,, but it had water in it,, so it went to the junk yard,,,

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OK Good try.

i just bought a 1995 mustang 5.0 HO that looked identical on the outside to my 94 OMC block... took it apart, side by side, it was a roller block... I switched the cams out , as the 95 mustang was a roller cam vs my regular old style cam... ,, but here is my question...when i pulled the heads,,, the pistons are both the same, flat with just valve grooves for both motors,,, a boat engine vs a mustang 5.0, i expected it to be a dished or domed top piston, but it is identical to the marine piston,, and i mean really identical to the marine piston... .it is an alluminum piston,, mine is a 94 omc boat block with reg cam and flat tappet lifters and carb, the 95 mustang had a roller cam and roller heads, ( the heads from a roller cam can not be used with a reg cam-- different spring rates, as i am told on the ford websites... ) ===== I really dont have any issues with any of this so far,,, I was prepared to change out the cam, pistons, and the crank,,, but so far,, the pistons are the same.... do i nead to change out the crank.. the mustangs 5.0 is rated at 240 horse,,, the 94 omc is rated at 190.....,, i understood the omc boat engine to have a forged crank,, but if the mustang 5.0 is rated higer,, do i need to change it out?

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This was a waste of time. The pistons look the same but are not. The Mustang pistons are hypereutectic alloy that is cast, while the marine pistons are forged. The iron in the block is a different formula, the internal thickness is less robust and, cripes didn't we tell you not to buy a car engine block?
There's nothing you can do with the Mustang engine. Go find a truck block.

As I have said before, I will go by your expertise,,, opinions, and general knowledge,,,, but if i dont have to change a crank,, that would save alot of money... thank you again four your help.....

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Now it seems like you're wasting our time. I suggest that you buy a remanufactured marine engine.

Find a donor block that matches the casting numbers of your existing block, and move forward.
Put a want ad on CraigsList.
Call your local machine shops.... these guys have suppliers that may have one.
Or.... find out who that supplier is, and go directly to them.

As for pistons..... what difference does it make regarding the pistons in the donor block?
You'll be replacing these anyway.... correct?

BTW, there is nothing wrong with using a piston that incorporates the Hypereutectic alloy and process. This is a special casting process that uses a special high silicone aluminum alloy, and has zero to do with the piston profile.
The important aspect of the piston will be the correct profile for the build that you want.
The Hypereutectic pistons are doing very well in the Marine builds.


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Thank you again for your help... I am moving forward.... this has not been a waste of time,,, we have learned so much... there has been 239 viewers that are reading and learning from this thread... most questions are on this site and other boat forums are about " will a chrysler 10 cly replace my 2.3 ford,,, or "my boat wont start .... did you check for gas/spark... type of questions::: this has been a great thread for anyone with a 5.0 ford... learning about flywheel housings,, "by the way..mine was a "ford only" housing,, not a uni-fit".. to types of blocks, pistons,,,, heads, forged cranks, marine gaskets for fresh water,,, ( i thought only salt water had to run them) etc.... yes i did not listen about the truck block,, but it was giving to me for free out of a great running mustang... and was looking good..,,,(after re-reading your post on car engines,, apparently not,), my bad for not listening, I did not mean to upset you and have you pissed that you gave up on me. (I know that without a few great leaders,, these sites would not exist) but i do not have the funds to buy a marine remanufactured engine,,, as i stated in my first message.... (i do... but wife and kids happiness comes first) I am now desperately looking for a truck block and will go with that when i find one... thank you again for your help...
ps.. i have the forged crank and pistons out of the "bad" engine and they look great,,but i have checked 20 ford sites for identification purposes and can tell the differences between the cranks and pistons of any of it.,,,,, as I said in my first post, i am a chevy man,, you could hit a forged crank with a hammer and hear the difference between forged and cast,,, but both the forged pistons and the aluminum pistons of the ford sound the same,,, and do not have casting numbers to tell the difference,,, ps this mustang was not an original engine,, it may be a truck engine and that is why it looks identical,, as the cranks look the same also....
I have tried to run the numbers on this ford block,, and ford is suppossed to have 8 numbers on the block near the starter to identify it,,, but both of mine only have 4 numbers,, and none make sense,,, only the heads numbers match anything,,, one flat cam,,, one roller cam,,,
thank you again for your help...

can tell the differences between the cranks and pistons of any of it,,,
I meant to say,, " cant tell the differences"..... none of the sites are clear about casting numbers,,, both of my blocks have 4 numbers,,, not eight...

Hey, we're not giving up on you....... we're here to help........ that's what these forums are for.

There seems to be a misnomer regarding crankshafts. All steel alloy crankshafts undergo a forging or hammering process (of one type or another) to add strength and flexibility that would otherwise not exist.
A die cast ONLY crankshaft would not hold up as well.

All pistons will be made from an aluminum alloy. Some will be cast, some will be forged, some will be pressure cast using a high silicone alloy like the Hypereutectic pistons.
The important part of the piston will be the correct profile for a Marine build...... I.E., piston deck being correct for the cylinder head chamber, skirt length, and for the correct static compression ratio.
Marine gassers must combat detonation affects and potential......., so we must keep compression ratios within reason.
Sometimes in small lighter weight GoFast boats we can get away with higher C/R's. But in our cruiser size boats, it's best to avoid this, and stay with what's tried and proven to work.

Tip: use the automotive forums for p/n gathering, casting numbers, year model differences, etc. etc. These guys live this stuff, and generally offer good info. But DO NOT follow suit for Marine build criteria.
If the auto guys do not, or have not owned a cruiser size boat, nor have cruiser engine build experience, they're not the right people to be offering Marine Engine build data, IMO.


If you plan to reuse pistons:

• Verify that the profile will render the correct static C/R. You can use one of the on-line static compression ratio calculators. Enter your engine data, the piston profile, and you'll be able to calculate C/R.
• Steer clear of a fully dished piston... or make sure that the SC/R is on the low side (full dished pistons do ZERO against detonation.... in fact, these can promote detonation when used with this style combustion chamber).
• Have a good machinist take a look at them and the block. He can take measurements to see if the bores are suitable for the pistons.

As for head gaskets being required for salt water engines only....... another misnomer.
This is all about the PH balance of the engine coolant, and an unbalanced coolant affect on the material used.
The automotive gaskets will live a short life when subjected to salt water. They will live longer if/when in river/lake water only..... but it's just a matter of time as to when they will eventually fail.
The Marine set uses a different material at the fire ring area that is not affected in the same way.

Some of the later automotive gaskets may incorporate this.... but check to make sure.


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