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Old 06-04-2012, 12:21 AM
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361/391

I have read that 361 and 391 FT's had the same bore castings as 428's. Is this true? How would I tell if I were to go look at one?
 
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Old 06-04-2012, 12:35 AM
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They have a 4.05 bore, are you thinking they will be thick enough to bore out to 4.13? If so, I think you will find it's a "maybe", depending on the particular block you find.

Try F600s and up, mostly up.
 
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Old 06-04-2012, 12:55 AM
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Originally Posted by 85e150six4mtod View Post
They have a 4.05 bore, are you thinking they will be thick enough to bore out to 4.13? If so, I think you will find it's a "maybe", depending on the particular block you find.
I have read that they can go to 4.13 and then be bored as far as a 428 can be bored. But I may have been dreaming.
 
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Old 06-04-2012, 12:56 AM
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Isn't there a drill bit test of some sort you can do on a 428? Would that work on a 391?
 
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Old 06-04-2012, 01:49 AM
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Drill bit test:

Cylinder Block | Mustang 428 Cobra Jet Registry

The pertinent passage:

"Measuring the gap between cylinders using a drill bit is the easiest way to determine whether your block is capable of supporting 428-sized cylinders. It is presently thought that if the shank of a 15/64" drill bit will NOT fit between the cylinders at any reachable spot in the six core holes, the cylinder will likely handle a 428 bore, core shift permitting....."

More discussion:

332-428 Ford FE Engine Forum: Cylinder wall thickness drill bit test interesting.....-----

and again:

332-428 Ford FE Engine Forum: 391 FT block to a 427 bore sonic #'s look good

The way to big cubes is the stroker way. Better to have a 4.080 bore with strong walls and a long stroke than paper thin walls with any stroke.
 
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Old 06-04-2012, 06:40 AM
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I've heard the FT motor's mite have a steel crank in them? I've never really looked into this but figured it was worth asking since I'm brainstorming my next "UP GRADE" build for my 390
 
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Old 06-04-2012, 08:06 AM
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Originally Posted by gpence View Post
I've heard the FT motor's mite have a steel crank in them? I've never really looked into this but figured it was worth asking since I'm brainstorming my next "UP GRADE" build for my 390
The 351/391's did, but the 359/389 did not. Same engine family, different cranks. And forget about using the steel crank, for the cost to prep it to use in a HP application, you can buy a stroker crank and make far more power. Cast FE cranks were never noted for breaking, there's no need for a steel crank for 99% of applications in an FE
 
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Old 06-04-2012, 12:55 PM
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fair enough figured it was worth throwing out their.
 
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Old 06-14-2012, 11:28 AM
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I have also read that FT's were externally balanced. Would an FT flywheel work on a 428 crank?
 
 
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