Flawebmaster

I have a FE cylinder block with casting number C7ME-A. I believe it is a service block out of a truck. The bore is standard 390 w. the single 390 style main web supports. The block has an X stamped on it. Could this be a 428 block? I want to bore it .080 over to standard 406. Thanks!

chipset

That engine could be 330MD truck
67 - 70 428
428-V4 police interceptor
cobra Jet
or 410 76 mercury.
The 390 has a 3 3/4 inch bore.
you have to take it a part and measure the crank.
I dought you will ever bore that block to 80 over. Piston size usually stops at 60 over.
Even if you did get 80 over that is a pretty thin wall.

Flawebmaster

The bore of a standard 390 is 4.050" which is what I believe my block to be. The standard 428 bore size is 4.13" which would be an .080" over 390. If my block is a 428 block, then shouldn't I be able to bore it .080, drop in a 428 crank and make it a 428?

chipset

Why don't you save yourself a lot of head aches and drop in a standard size 428
piston set in your 390 block with the original crank and rods. They fit. you then have to
have your rotating mass balanced. That combination will EAT any 428 out there. The stock 390 maximum r.p.m. based on piston speed is 5,556 r.p.m. The 428 maximum r.p.m. based on piston speed is 5,276. your 390 with the 428 piston combo will, with
very little add ons will get you just this side of 400 h.P. The stock 390 comes in at 389
H.P. They had to under rate the H.P. for nascar racing.

mil1ion

Sounds like a 361 Block from a Medium duty truck

Flawebmaster

Thanks for the info. I have a nice 390 crank and a set of CJ rods. Are you saying that I can use standard 428 pistons with my 390 crank? I assumed the 428 piston would have a different pin height due to the increased stroke?

chipset

You use the 428 pistons with the standard 390 rods and crank. Nothing but the bore
size changes. you still have the 390 stroke. Just make damn sure you have the new
rotating mass balanced as the cylindar walls of your 390 will be so thin you could
shake the cylinder walls apart. Not a good idea. usually makes for a BIG BANG.

FFR428

That doesn't work. 428 pistons have the pin location higher for the longer 3.98 stroke. If you use them with the 390 crank they will be .100 lower than the 390 stock.

chipset

pin height or compression height in the 390 and 428 are identical.
390-- 1.660
428-- 1.660
The only thing that is different is the pin size.
390-- 1.402
428-- .9752
You have to bush down the 390 rods to fit the 428 pins.

FFR428

All FE piston pins are the same size @ .975. 390 or 428 they are both the same pin dia. Yes comp height is the same but the pin height is higher on the 428 pistons. That's how they are able to both use the same length rods.