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One of the cars that I am looking at has a 390 engine. It has a bunch of modifications, including a 427 crank. My question is this: Does that 427 crank (and I'm assuming matching rods) make it a 427? Or would it have to be bored out to accomplish that? I'm not familiar with the 390/427 engines, so I don't know if they share the same bore. TIA :)
 

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One of the cars that I am looking at has a 390 engine. It has a bunch of modifications, including a 427 crank. My question is this: Does that 427 crank (and I'm assuming matching rods) make it a 427? Or would it have to be bored out to accomplish that? I'm not familiar with the 390/427 engines, so I don't know if they share the same bore. TIA :)
No 427 crank does not make a 390 a 427, 427 bore is much larger
390 stroke is same as 427
Block on a 427 has more material to allow for the 427 bore
 

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Ah. So what the hell does adding a 427 crank accomplish? Is it stronger or something?
If I remember right, don't quote me, but I think they're steel.
I'm not sure if they're all steel or just some.
 

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I think the 427 had steel cranks from 1965-67 and the others were nodular iron for 1963, 64 and 68. Also some 360/390 truck had steel cranks.

The 427 & 390 both had a 3.78" stoke and bores were 4.23" and 4.05".

The nodular crank is good for 6000+ rpm with a good tune and balance.

I had two and they saw 6000 many times back in the days. Most important is rods and rod bolts.

I am not an engine builder like the good guys on this sight but have put together a couple 427 center oilers engines.

Mike
 

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I think the 427 had steel cranks from 1965-67 and the others were nodular iron for 1963, 64 and 68. Also some 360/390 truck had steel cranks.

The 427 & 390 both had a 3.78" stoke and bores were 4.23" and 4.05".

The nodular crank is good for 6000+ rpm with a good tune and balance.

I had two and they saw 6000 many times back in the days. Most important is rods and rod bolts.

I am not an engine builder like the good guys on this sight but have put together a couple 427 center oilers engines.

Mike
Mike has pretty much nailed it, except that the 360-390 cranks were all cast, however the 361 &391 FT engines used in the larger trucks (Louisville, COE, and F500-600 etc) had steel cranks. However the361-391 truck cranks have a much larger front crank snout and pilot bearing flange, which need to be machined down to fit a car timing cover and crank gear, and car sized torque convertor or pilot bushing/bearing. The factory cast cranks are pretty stout, I run a .010-.010 cast 428 1U crank in my Fairmont, 14 years of low 10 second 1/4 miles, 66-6700RPM thru the traps, and it still always passes Magnaflux testing. A couple of buddys with 454`s (427 block with a 428 crank) have been running the stock cranks for years as well, trapping 7500 RPM!
 
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