Hey I saw in a post in 67-72 about you saying somethin about offset grinding a 390 crank to get over 421 cu. what is this?

 

#####, because Ford V8s have large bearing journals as compared to brand C engines, this gives us a very nice opportunity. When regrinding a crankshaft, one does not have to remove metal evenly around the rod journals. If the rod journal is ground down from the stock FE size of 2.438 to 2.200, removing all the metal from the inside of the throw, an increase of stroke is possible. I like a 4 inch stroke, just a little more the the factory 410/428s. The 2 inch throw is easy to setup on the lathe and the installed height works out well. I prefer connecting rods from crower or lunati, they are intended for a big block C engine and are available in a 6.536 length. You will have to narrow the big end of the new rods about .125 on the outside of each, the bearings will be fine as they are. Next the small end of the rods will need to be bushed down to .975. For pistons you can use TRW L2291s with the top milled down about.125 or the low-compression 410 pistons that many truck 390s have could be used with only .020 cut from the tops. If you are brave enough to bore .080 over, you can use 428 pistons milled .020 speed pro 2303s are the # I think. A 060 over 390 stroked in this manner will give just over 421 inches. The aftermarket rods will set you back about 500$ but this is becoming a good option as the price of 410/428 cranks climbs out of sight. The oil holes will 'walk 'away from the center of the journal as it gets smaller so try to start with a crank that is nicely drilled, some of Fords machine work was kinda sloppy in the late 60s and early 70s. 3 out of 4 cranks that I've seen look like they are up too it. Expect to pay double for the fancy grinding on the crank, and maybe 200 more for rod and piston work. The resulting small journal 410/428 is very lively and lots of fun without exspensive 428 parts ! Have fun. DF

 

hey DF have you ever noticed if the FT cranks have better machining? it seems like if they were better machined since they were forged you'd get a better deal.

 

that is correct, Ford was sometimes a little more careful on the heavy duty forged cranks in the FT. The 391 FT crank would make a great start for a super duty 390 stroker buildup. The snout must be turned down to passenger size, and the spot where the pilot bearing goes sometimes needs to be shortened. If you find a 391 FT, get the block as well, they are frequently a beefier casting that normal and more likely to be able to take the 080 overbore. DF

 

the correct part number for the 428 forged pistons is L2245F, from TRW/speedpro. Available in std 030,040,and 060. DF

 

Another trick is to use the rods from a 300 I6 with your offset ground crank. The pin diameter is the same. I haven't done this but a couple of friends did it years ago using 302 conecting rod bearings in the 300 rod. They had to narrow the 300 rods but they got a lot of cubic inches for a high torque engine, cheaply. I believe they actually started with a 428 crank. I don't recall just what the final stroke was.

Center-Center Crank Pin Diameter Bearing Width
300 rod 6.2082-6.2112 2.1236 0.790-0.810
390 rod 6.4860-6.4900 2.4384 0.724-0.734
302 rod not an issue 2.1232 0.706-0.726

I'll try to determine just what the stroke was in the next day or two.

Bob
'66 7 Litre Convertible, top loader, 3.25 Traction-lock, 427 Sidewinder Intake, 780 Holley, Windage tray, SCJ Exhaust manifolds, H-pipe, MSD, Line-lock, AM/FM/8-Track/CB
'88 F150 XLT Lariat, 302, 5 speed, 3.08
'98 Mustang, 3.8, 5 speed
'99 Ranger, 3.0, 5 speed, 3.73 posi

 

i have an engine but don't know what it is and dont know any one with a book of #'s they are c i or 1 a e -g 4h b2 1 if know tell me please

 

Jayson, you need to start a new thread with your questions to get maximum replies. You also need to be as specific as possible so that the fine folks around here can try to help you, i.e. what year truck, # of cylinders, location of casting numbers, original or swap, etc.