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1976 Fleetwood Brougham d'Elegance, 1990 Allante
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190 Posts
Discussion Starter #1
I've found a machine shop nearby that will give me a pretty good deal on boring the old 368 I have out to .030 over 500. $210 for hot tank, magnaflux, bore, hone, and paint.

Before I have this done, though, I'd like to know if there are any problems with doing this. The engines are built on the same block, but is there any difference in internal construction (ie the water channels) that would make this impossible?

Thanks in advance!

- Joe
 

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'80 Fleetwood Coupe, 1994 and 1995 Mercedes 140 Coupe
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2,096 Posts
Your machine shop guy is breathing too many CRC fumes.

The 368, 425 and 472 all share the same stroke. The 500 has a longer stroke.

You cannot overbore the 368 anywhere near enough to make it 500 C.I.
Maybe the machinist missed a decimal point somewhere in the calculation.

368 has much smaller ports in the heads. Everything is designed for gas mileage.

Take a look on this site for tune-up specs for different years and engines to get an idea of bore and stroke amounts.

Easier just to find a 500. They are not that rare.
 

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Registered
1976 Fleetwood Brougham d'Elegance, 1990 Allante
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190 Posts
Discussion Starter #3
I wasn't planning on keeping the same heads. I was going to get 76cc heads for a 472/500 for it, a 500 crank, and a 500 valvetrain.

The machinist is actually the one who told me to check on this before I brough him the block. He was worried about hitting a coolant passage, but wasn't familiar enough with the Caddy engines to say for sure whether or not he would.

You are right about how it's easier to find 500's. I may go with that and just get rid of the 368.

- Joe
 
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