361/391

Reply Subscribe

Thread Tools

Search this Thread

Jun 3, 2012 | 11:21 PM

1972RedNeck

Thread Starter

Logistics Pro

Joined: Feb 2011

Posts: 3,522

Likes: 11

From: Townsend, MT

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?

Jun 3, 2012 | 11:35 PM

85e150

Super Moderator

Joined: Apr 2004

Posts: 34,476

Likes: 2,800

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.

Jun 3, 2012 | 11:55 PM

1972RedNeck

Thread Starter

Logistics Pro

Joined: Feb 2011

Posts: 3,522

Likes: 11

From: Townsend, MT

Quote:

Originally Posted by 85e150six4mtod

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.

Jun 3, 2012 | 11:56 PM

1972RedNeck

Thread Starter

Logistics Pro

Joined: Feb 2011

Posts: 3,522

Likes: 11

From: Townsend, MT

Isn't there a drill bit test of some sort you can do on a 428? Would that work on a 391?

Jun 4, 2012 | 12:49 AM

85e150

Super Moderator

Joined: Apr 2004

Posts: 34,476

Likes: 2,800

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.

Jun 4, 2012 | 05:40 AM

gpence

Elder User

Joined: Oct 2011

Posts: 842

Likes: 0

From: Palmyra

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

Jun 4, 2012 | 07:06 AM

baddad457

Hotshot

Joined: May 2003

Posts: 11,141

Likes: 25

From: south louisiana

Quote:

Originally Posted by gpence

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