SpeedTalk Store - Opinion Columns

Ford 390 FE Block overbore limits

General engine tech -- Drag Racing to Circle Track

Moderator: Team

Ford 390 FE Block overbore limits

Postby ProPower engines » Thu Feb 04, 2010 3:21 am

Have any of you ford guys bored a 390 block to 428 bore size with any luck?
Looking for block numbers that may work if there are any prefferences to year.
Never tried so asking before wasting time doing it if there is no way.
Thanks
Real Race Cars Don't Have Doors
ProPower engines
Guru
Guru
 
Posts: 5350
Joined: Sun Jan 21, 2007 1:16 pm
Location: VICTORIA BC CANADA

Re: Ford 390 FE Block overbore limits

Postby robert1 » Thu Feb 04, 2010 7:45 am

We never sonic checked one but we had to sleeve quite a few. 390 FEs always go into water with a thin wall sleeve. Very thin cylinders.
robert1
Guru
Guru
 
Posts: 2481
Joined: Fri Oct 26, 2007 7:26 pm
Location: missippippi

Re: Ford 390 FE Block overbore limits

Postby Dave Flanders » Thu Feb 04, 2010 8:05 am

You'll never know without a sonic check. A friend of mine just had a 390 bored to 4.13" with room to spare but that was after checking a couple different blocks. Would you really chance going that far over just on someone's opinion on wall thickness?
Flanders Racing - bringing you yesterday's technology today!
Dave Flanders
New Member
New Member
 
Posts: 45
Joined: Wed Oct 19, 2005 6:33 pm
Location: Zeeland, MI

Re: Ford 390 FE Block overbore limits

Postby Blueoval Ralph » Thu Feb 04, 2010 8:52 am

ProPower engines wrote:Have any of you ford guys bored a 390 block to 428 bore size with any luck?
Looking for block numbers that may work if there are any prefferences to year.
Never tried so asking before wasting time doing it if there is no way.
Thanks


390 is very thin if you case find information form Ford on the 1962 406 they talk about revising the the water jacket core for the bore change of the 406.
Ralph
Blueoval Ralph
New Member
New Member
 
Posts: 24
Joined: Wed Jan 27, 2010 2:40 pm

Re: Ford 390 FE Block overbore limits

Postby rmcomprandy » Thu Feb 04, 2010 9:14 am

Dave Flanders wrote:You'll never know without a sonic check. A friend of mine just had a 390 bored to 4.13" with room to spare but that was after checking a couple different blocks. Would you really chance going that far over just on someone's opinion on wall thickness?


EXACTLY ... sonic checking THAT block is the only way.
I have seen some 390 blocks with 428 water jacket cores and those are thick enough to go larger than norm.
rmcomprandy
 

Re: Ford 390 FE Block overbore limits

Postby ProPower engines » Thu Feb 04, 2010 12:44 pm

rmcomprandy wrote:
Dave Flanders wrote:You'll never know without a sonic check. A friend of mine just had a 390 bored to 4.13" with room to spare but that was after checking a couple different blocks. Would you really chance going that far over just on someone's opinion on wall thickness?


EXACTLY ... sonic checking THAT block is the only way.
I have seen some 390 blocks with 428 water jacket cores and those are thick enough to go larger than norm.


I know that there are some thicker than others but was lookin for info if any on what year blocks may be a good choice to start with.
I would sonic test before boring anyway but just lookin for the right block to start with.
Customer has a pile of blocks but not a pile of money to clean and checkthem all.
Real Race Cars Don't Have Doors
ProPower engines
Guru
Guru
 
Posts: 5350
Joined: Sun Jan 21, 2007 1:16 pm
Location: VICTORIA BC CANADA

Re: Ford 390 FE Block overbore limits

Postby brechlrl » Thu Feb 04, 2010 3:21 pm

ALL 390 blocks need to be checked. Many will only take .030 if you want to maintain .100 wall.. Core shift is the primary culprit. A non shifted bock may take .130 over bore. It has been done many times but sonic check is the only way to tell. You have a better chance with a 68-76 light truck "105" block of getting a thicker cylinder, but no guarantee.
brechlrl
Member
Member
 
Posts: 149
Joined: Mon Nov 30, 2009 3:35 pm

Re: Ford 390 FE Block overbore limits

Postby dwilliams » Fri Feb 05, 2010 7:56 pm

Every performance FE build needs to be sonic checked.

The foundry apparently only changed the minimum number of cores when they switched bore sizes. You sometimes run into walls that are very thick, most often paper thin. The cores were highly tapered, and the FEs are even thinner at the bottom than the top.

Every now and then I manage to score a 361 or 391 FT block from a medium-duty truck. They're a bit thicker than the car blocks on the average. Before there were cheap drop-in stroker assemblies, a 391 block, 400 Chevy pistons, Slant Six rods, and an offset-ground 390 crank made a nice 443 cubic inch stroker. Nowadays with cheap 3.98" and longer aftermarket cranks available, it's not worth the trouble.
dwilliams
Expert
Expert
 
Posts: 808
Joined: Sun Oct 15, 2006 9:00 am

Re: Ford 390 FE Block overbore limits

Postby Barry_R » Fri Feb 05, 2010 9:58 pm

I would not cut one more than .040 without a sonic - and I have built a bunch of them. You can flashlight into the water jacket below the front & rear coolant openings in the deck and they'll sometimes have the "428" cast into the floor - or below the center freeze plug. If it says "352" or nothing its not likely to go very large without grief. I make a bunch of them up as strokers instead of going big on the bore. It seems to work really well to +/-445"- no block grinding at all - and safer than drilling for water...
Survival Motorsports
www.survivalmotorsports.com

WD for Comp, Manley, Blue Thunder, Diamond
Probe, Holley, Clevite, Federal-Mogul, Scat....
Barry_R
Expert
Expert
 
Posts: 976
Joined: Wed Jan 18, 2006 8:57 pm
Location: Detroit area

Re: Ford 390 FE Block overbore limits

Postby Dave Flanders » Fri Feb 05, 2010 10:35 pm

My mistake - I did check with my friend who went to 4.13" on his and it was a 391 block out of a motorhome. He didn't remember the casting number though, will have to check that later.
Flanders Racing - bringing you yesterday's technology today!
Dave Flanders
New Member
New Member
 
Posts: 45
Joined: Wed Oct 19, 2005 6:33 pm
Location: Zeeland, MI

Re: Ford 390 FE Block overbore limits

Postby Racerrick » Sat Feb 06, 2010 1:29 pm

When the Michigan took over casting the block in 1973 or so They revamp the block. The d4te casting is heavier. This block is also known as the 105 mirror block and its the only one I use to build fe's unless its a number match deal.
Racerrick
Pro
Pro
 
Posts: 424
Joined: Sat Sep 24, 2005 9:52 am

Re: Ford 390 FE Block overbore limits

Postby CNC BLOCKS » Sat Feb 06, 2010 1:43 pm

We are working on 428 CJ for a customer and he brought in about five 390 blocks that were bores .100 over and was told they were sonic tested and after checking them out the average thin spot was about .050 thick.

He did hapeen to find an origanal 428 that had been obres .030 and sonic tested fine.
Website is up and running
http://hinksonautomotive-cncblocks.com/
Machine shop tour
http://hinksonautomotive-cncblocks.com/shop-tour/
Monthly Specials
http://hinksonautomotive-cncblocks.com/specials/
Soon 55MM babbit cam bearings with 1 hole
CNC BLOCKS
Guru
Guru
 
Posts: 4516
Joined: Thu Jul 01, 2004 5:34 am
Location: NORTHEAST


Return to Engine Tech

Who is online

Users browsing this forum: blueviper2t, carzngunz, Google [Bot], Greg Long, gtca9014, mark gummo, rp930, seancarole, vortecpro and 22 guests