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Discussion Starter #1
I am close to doing an engine swap on my 68 302. I want to get a roller 5.0 H.O. from a 85-92 mustang because they come with forged pistons and they have roller lifters etc. What benefits do the later year 5.0 have over the older 302's? Is it worth buying a core 5.0 motor? Can I have the 302 rebuilt and be just as good or better than a 5.0 H.O.?
 

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Stick with the 87-92 5.0 if you want a good 302 and intend on using the EFI system, plan on the 89-92 as it has mass air over the 87-88 speed density system. The advantage of the roller motor is less friction due to the roller cam and a bit more performance with less dollars. You can get the same performance from an older 289/302 block but it will cost more and see more wear and tear if left to conventional valvetrain & cam.

That being said, I would stick with the original motor and spend the money to upgrade it. It would be easy to get 300-325 hp from a 302 depending on your budget. Anymore than that power wise would require other upgrades like stroking & power adders (Supercharger/Nitro/Turbo)
 

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Discussion Starter #3
i dont plan on running EFI I'll do a carb conversion.....its just easier
 

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'86 is about the only year 5.0 you need to steer clear of. Flat top pistons with no valve reliefs and heads with big block sized combustion chambers.

Really, there's no difference between the older 302 and 5.0 blocks other than the roller cam. If you want to run a roller cam, it's going to be a LOT cheaper to run a 5.0 block. Retrofit roller lifters for the 302 blocks are very expensive. EFI or carb, everything bolts to the heads, so it doesn't matter what block you run.
 

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The 302 crankshaft is superior to the 5.0

The 50 oz imbalance of the 5.0 results in a crank with different bobweight profiles. (I think that describes it properly.

There are some later model 5.0 heads that have excellent flow characteristics

You can put forged pistons in anything and roller rockers will work in a 302 block if you use the proper retro rollers set ups

I have no doubt that a modern piston with modern ring packs will have less friction than old style pistons and rings. That can be a big horsepower savings.

Which brings me to the conclusion that mixing and matching stock 302 and 5.0 parts if done with care might well exceed either engine's original strength and durability.
 

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The original 302's were "smog motors"- small intake ports, etc- basically very choked down (this actually started in 1966). The original block has great potential (289/302's have produced up to 700 hp normally asperated), but the roller versions (as described above) are really excellent platforms left as is or built upon as well!

IIRR- Hot Rod Mag did a build up on one back in the 80's, de-stroked it to 290 cid and I think it cranked out 650 hp @ 6500 rpm
 

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wait so the older blocks will hold more power than the newer roller blocks ?

I want to do a turbo, or a blower set up on my 302 eventually but I heard the roller blocks only hold like 450-500hp to the weels ???

how do I identify my year block with out taking things apart ? I know it's not the original motor.
 

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The 302 crankshaft is superior to the 5.0

The 50 oz imbalance of the 5.0 results in a crank with different bobweight profiles. (I think that describes it properly.

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How does this make it superior?...Most performance builds I have seen either go fully internally balanced or use the older 28oz balance...

Getting back to the original question you can do anything to an older block that you can to a 5.0...The nice thing about the 5.0s is you can pick them up cheap where it would cost you a couple thousand to end up with the same thing in your old motor..Mind you the old motor would be fresh for that price..
 

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wait so the older blocks will hold more power than the newer roller blocks ?

I want to do a turbo, or a blower set up on my 302 eventually but I heard the roller blocks only hold like 450-500hp to the weels ???

how do I identify my year block with out taking things apart ? I know it's not the original motor.
All factory 302 blocks (5.0s included) are pretty weak for big HP. Everyone raves about the thicker HIPO 289 main caps and main girdles, but the problem is not with the caps, it's with the main webbing in the block. Cracks develop in the main web where the bolt holes are and migrate up, eventually cracking along the lifter valley. No amount of thicker caps or girdles is going to prevent the block from letting go.

Here's a good page showing how these cracks develop.
The Turbo Forums.com
 

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I think mine is an '86 block. Should be a roller motor right ?
 

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I think mine is an '86 block. Should be a roller motor right ?
Should be. Look in the lifter valley and check to see if it has two raised bosses that are threaded. In the pic, it's the round deal between the cast "351" and "WCP-13".

 

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Earlier Mexican blocks were a little stronger with better iron. But still not going to hold up to 700 HP for very long.
I think it was just the first couple of years that came with forged pistons, and roller blocks were used up to and including '95 year model.
 

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Should be. Look in the lifter valley and check to see if it has two raised bosses that are threaded. In the pic, it's the round deal between the cast "351" and "WCP-13".

cool thanks

anyway to tell with out taking things apart ? also can a roller block use a non roller cam ? after I blew up my 289 and got a rebuilt 302 put in I still have the same 351 firing order from the wrong 351 cam I put in th 289 I assume ???????
 

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Discussion Starter #15
What if I take my existing 302 to a shop, hand them a set of gt40 heads, and an edelbrock cam & lifter kit (re-use my edelbrock performer intake) and have them put it together???
 

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Earlier Mexican blocks were a little stronger with better iron. But still not going to hold up to 700 HP for very long.
I think it was just the first couple of years that came with forged pistons, and roller blocks were used up to and including '95 year model.

Mexican blocks do not have a stronger iron formulation. It's the same as any US SBF. Just the main caps are thicker, the rest of the block is basically the same.
 
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