391 truck block

[galaxastang]

I have chance to pick up a 391 truck block D4TE-1 cheap. Any differences from the 390 block? Will Barry R's 445 kit work with those blocks? I know the crank is different, anything else I should look out for? Thanks

[jayb]

The 391 truck blocks have a different diameter for the lower distributor shaft, down near where the oil pump driveshaft fits in.  Ford used to make a bushing that would press into that hole in the block and allow a standard FE distributor to be used, but they've been unavailable for a while now.  You could probably have a bronze bushing machined to fit; no big deal, I guess.  Some of those 391 truck blocks are really thick, I've got one like that.  Mine could easily be bored to 4.13" (428 size) based on the sonic numbers.

[galaxastang]

Thanks Jay, I remembered there was a bushing needed but could not remember where it was needed. Think I'll pick it up.

[thatdarncat]

Precision Oil Pumps has the special bushing for the distributor, see the link. My experience, and I've only checked about a dozen 391's, is that it is a window of only a couple years around '71-'72 that have the thick 428 cylinder cores. But certainly check any you come across. One other thing, 391's usually have a threaded hole right above the oil pan that was for an oil return line. It just needs a plug.

http://stores.precisionoilpumps.com/-strse-159/Bronze-Ford-FE-Truck/Detail.bok

[chris401]

Yours were external ribbed blocks? That's cool I didn't know they had a chance of thick cores. His is a D4. The two I had D3 and D4 both had thick walls but were both pick-up truck blocks with standard 360 or 390 cranks. I still have the D3TE. It needs 3 sleeves, due to core shift, to go 4.13 and keep .100 wall. Its bored 4.080 now but the other 5 cylinders will be good for 4.17 bore with .100 left.

[John Krag]

I'd save the crankshaft out of this block.They are steel and the only machine work you have to do is on the "snout" for an FE balancer to fit. With all this chinese junk floating around it would be worth the investment to have the crank machined."American steel"  can't be beat.

[Randy]

Yes I would grab it I used one and built my SOHC out of it I was able to go out to 4.170 and I am running 11.5.1 pistons, it also has larger gussets going to the mains to beef it up, mine says in the frost plug holes 428 in 2 spots, the guy that lined honed it for my say they used 428 cores in the 391 blocks and only bored them to 390 specs.

[thatdarncat]

Randy, just out of curiosity, what is the date code on your block? Is there a casting number?