Ford 390 FE Block overbore limits

[ProPower engines]

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

[robert1]

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.

[Dave Flanders]

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?

[Blueoval Ralph]

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

[rmcomprandy]

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.

[ProPower engines]

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.

[brechlrl]

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.

[dwilliams]

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.

[Barry_R]

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...

[Dave Flanders]

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.

[Racerrick]

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.

[CNC BLOCKS]

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.