390 bored to 427

J

johnsstang04

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#1

• Jun 4, 2006

• #1

I came across a 390 that was recently rebuilt and bored to a 427.. or so the owner says. I think it's out of a 69 or 70 pickup. Its been built up a bit, runs well and has a C6 trans. I have two questions... what is the engine worth? Also, I have a '69 convertible that had a 302 stock. Would the car be worth more or less if restored with a 390? I know people always say numbers matching is best, but personally it seems bigger is better, and considering a factory 390 is worth way more than a 302, maybe the car is worth more with the 390.

 

Max Power

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Jul 31, 2003

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St Paul

Jun 4, 2006

#2

• Jun 4, 2006

• #2

Not sure what the engine is worth, but you cant bore a 390 to a 427.

 

J

johnsstang04

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#3

• Jun 4, 2006

• #3

I should say bored and stroked... sorry about that

 

Max Power

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St Paul

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#4

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Actually, I don't think you can bore and stroke a 390 to a 427 either. I may be wrong, but I don't think that block supports a big enough bore to do it. I would get receipts or documentation.

 

65ShelbyClone

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#5

• Jun 5, 2006

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As far as I know about the farthest you can take a 390 block is 400 or 406 or right around there. I think that involves using a 428 crank, but I'm not an FE expert. I don't think even sleeving a 390 will get it to 427 inches. FEs have notoriously thin cylinders, so thin in fact that many 427s will not tolerate even a .030 overbore without sleeves.

Your '69 wouldn't be "restored" if you put a 390 in it. Being a convertible I think it will be more valuable in stock configuration. Yes, a factory 390 GT is worth more than a 302 GT, but your car isn't a GT nor even a factory big block. Anyone can get a 390 truck engine, warm it over, and put it in a '67+ Mustang.

 

G

grainboy

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Jun 5, 2006

#6

• Jun 5, 2006

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Putting a 428 crank into your 390 will yield you 410 CI. Some blocks have enough cylinder wall to safely bore to 428, some do not. You need to bore .080 over. My machinist says to use 360 truck blocks for the el cheapo 428.

 

jerry S

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Sep 3, 2003

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Jun 5, 2006

#7

• Jun 5, 2006

• #7

65ShelbyClone said:

As far as I know about the farthest you can take a 390 block is 400 or 406 or right around there. I think that involves using a 428 crank, but I'm not an FE expert. I don't think even sleeving a 390 will get it to 427 inches. FEs have notoriously thin cylinders, so thin in fact that many 427s will not tolerate even a .030 overbore without sleeves.

Click to expand...

It can be done. I came across more than one engine builder offering a 390 stroked to 427 and some that offer 434 and 449 stroker kits

http://www.strokerkits.com/new_page_6.htm

and here is speedomotive's 445 stroker

http://www.speedomotive.com/fe_ford_390_to_445_cid_stroker.htm


Whether the engine will last is an open question, however.

 

D

D.Hearne

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Jun 5, 2006

#8

• Jun 5, 2006

• #8

SOME 390 blocks can be bored .080 to yeild a 428 size bore, but most can't. 427's used the same crank as a 390 (3.78 stroke) 428's used a little longer throw crank (3.98) to yeild the same cubes with a smaller bore ( 4.28 bore is 4.13, 427 is 4.23.

 

65ShelbyClone

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#9

• Jun 5, 2006

• #9

jerry S said:

http://www.speedomotive.com/fe_ford_390_to_445_cid_stroker.htmIt can be done. I came across more than one engine builder offering a 390 stroked to 427 and some that offer 434 and 449 stroker kits

Whether the engine will last is an open question, however.

Click to expand...

I guess I shouldn't be surprised, but that is a lot of stroke to fit in there.

I was thinking about durability too. By the time it gets to 449ci, it probably has a bore:stroke ratio rivaling a diesel. Not bad if you keep it under a diesel-style redline of 3500rpm...

 

S

Sicarius428

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Jan 6, 2004

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#10

• Jun 5, 2006

• #10

I would be careful with that one. Though some can be bored out that large... with most 390 blocks you will hit water first.
Kevin

 

J

johnsstang04

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Jun 5, 2006

#11

• Jun 5, 2006

• #11

Thanks for the help. I bought the engine... it seems life is better when you have a big block sitting in your garage, even if its just a 390. I know I've heard of them being bored/stroked to a 427. When I get the motor I'll pull the heads off and see what it is.

 

S

Sicarius428

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Jan 6, 2004

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#12

• Jun 5, 2006

• #12

Life is better with a big block. Congrats on your buy. I'm sure you will be pleased.
Kevin

 

D

danny clemens

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#13

• Jun 5, 2006

• #13

You might be able to stroke a 390 to a 427 but you can't bore a 390 block out to the 427 bore of 4.230. One of the main reasons Ford quit making the 427 was because it was very expensive to make. The bore was so big that the slightest core shift would make the block unusable. There was very little margin for error. The 390 has a reputation of being slow but if you put a good set of heads on a 390 it'll wake it up. You can check to see if it has a longer stroke by measuring through a spark plug hole.

 

C

commonrail

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#14

• Jun 6, 2006

• #14

I had a full size merc' 67 Park Lane with a 410 in it. I had the engine out, and it is like I've read here. A 390 bore, with a 428 stroke. The wrist pins were high on the pistons as I recall, making pistons unique to the 410.
It was a good torque motor.
Good luck with your FE !