390 bored .030

wtenukl · #1 (**permalink**) 10-25-2004, 08:02 PM

Hi, I'm new to the Ford FE family and I need some help please. I bought a Cobra with a 428FE(at least, that is what the guy said it was) and I just had some major work done on the engine and my mechanic said that the engine is a 390 bored .030 over. I've heard some other explenations, but could someone please tell me if this engine is cosidered a 428 or not? I don't know too much about the engine besides what I've had done to it. Besides what I have already wrote, it now has Edelbrock Performance aluminum heads, forged pistons, dual quad 600's, an aluminum intake, and a Comp cam. Thanks for your help.

FFR428 · #2 (**permalink**) 10-26-2004, 03:01 AM

The 428 has a cyl bore of 4.13 and the 390 a smaller 4.05. Also the stroke of the 428 crank is longer at 3.98 vs the 390's 3.78. Your 390 at .030 is a 4.08 bore. For it to be a 428 it would have to go .080 but not recommended without a sonic check. So your answer is no it's not a 428. The 390 will be fine but you may want a word with the fellow who sold you the car.......G.

Clois Harlan · #3 (**permalink**) 10-26-2004, 05:54 AM

Another thing if you have the engine out of the car. The 428 engine has a 28 oz. balancer on the flywheel and the harmonic balancer. The 390 is internally balanced and should not have any balancing weights on the either end of the crank.

Clois

trularin · #4 (**permalink**) 10-26-2004, 06:01 AM

Good call Clois.

Is the engine still out of the car?

Check numbers!!! Crank, rods and everything else. Get a complete picture of what you have.

bmcmillan · #5 (**permalink**) 10-31-2004, 08:03 PM

tenukl,

A pretty common conversion is to buy a 428 crank and bore the 390 .080" over. It is a good idea to sonic check the block anyway - cheap insurance. Like the others said, you have to use everything 428 from balancer to flywheel/flexplate.

You have ended up about 397 CI. Some of the Ford race engines - the 406 and the 410 were either stroked or bored 390's. The 428 was a sroked and bored 390.

There are some interesting combinations that make great engines, such as converting a 390SP to a 428. You end up with higher-compression, solid-lifter, pump-gas FE that is more practical with today's gas than a 11:1 - 12:1 427 side oiler.

You still have a little work to do if you want a 428.

Good luck,

Brian

Excaliber · #6 (**permalink**) 10-31-2004, 10:53 PM

Sounds like the motor is done. It's a good 390 well built, let it go. Drop it in and have fun!



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