Could I replace a FT 361 crank for a FE 428 crank in an FT engine?

I hear the reverse of putting a larger/heavier FT crank in an FE engine is simple, requiring to grind the crank ends down to fit the smaller middle hole in the damper and flywheel/flexplate.

Would I need FE main bearing caps? Are they the same diameter in FE and FT blocks?

Tyl

 

The crank snout is larger on the FT engine. That is why they take them, grind them down and use them in FE's. Can't see how it could go the other way.

 

How about using a 330MD timing cover to make up for the snout difference? And, of course, using the correct 428 flywheel and damper. (not sure the balance weight on the 428 is the same as a 391 FT).

 

Is the main bearings the same size for an FT/FE crank? The FT crank is larger, but if the main bearinmgs are the same size...

Art, I would be considering buying a fe damper, if the crank mains are the same. A new flywheel might be a bit complex to the setup I currently have. I'm thinking of welding on a fe spacer to the larger diameter center of the existing flywheel.

Tyl

 

Clearances are different between FT and FE - more as a longevity thing for the FT's - more clearance, more able to take the heat.

Going from my Motor's manual:

361/391 crank pin diameter 2.4377-2.4385 (clearance .001-.0029) main diameter 2.7479-2.7487 (clearance .001-.0029)

330MD/HD/352/360/390/428 crank pin diameter 2.4380-2.4388 (clearance .0008-.0026) main diameter 2.7484-2.7492 (clearance .0005-.0025)

So it looks originally, an FT has .0003" less on the crank pins, .0005" less on the mains.

Looks like it would fit right in the middle - just check the clearances during assembly (as always).

If you're going for a longer stroke - are you doing anything with the piston height?

The 428 has .2" longer stroke - I don't think the deck height is that much on an FT, is it?

 

That's a load off. Grand to hear the mains are the same.

I bought a set of the short connecting rods; C6AE-C, and will have a set of those 410 pistons that the pin is lower than conventional pistons.

I'm not sure either on the deck height. I would assume it is the same as a FE motor. Everything else has the same porpotions.

Tyl

 

Well Art maybe its just me? But with the 391 crank working in a FE 390..with just a timing change cover..I'am sure one us Rodders would have figured that out? So that would meen instead of Changing the Diameter of the snout...the FE Guys can run a 391 steel crank in there motor's By just changing the timing cover?

Escuse me if I read this wrong.....I'am learning daily!!

RJ

 

That's always been my understanding.

The problem is, the cast-iron FT timing cover has the motor mount attachment points. If you can ignore that, I guess it would work... I think accessories might be an issue, but that can be worked around too.

I did a lot of research when I first started doing the work for the 390 in my highboy. My machinist, the engine balancer, and a few other people who had done a fair amount of Ford racing in the late 60's and early 70's said it was a well-known(?) way of getting an FE steel crank - either machine the snout, or use the FT timing cover.

Forgot to mention above, might want to check crank end-play specs too, might be looser for the FT.

 

Oh, one other thing. Everyone I talked to that said using the FT crank was possible, also said "Why bother? The FE crank can handle anything YOU are going to throw at it" - as in, normally-aspirated, no nitrous, and nothing above 6500RPMs.

And it's HEAVY

 

Yeah OK Art, I hear where your coming from....I have a few friends running excess of 7500rpms and a few have used the FT cranks....But all have turned the snouts down..I just wasnt aware of leaving the snout the same Diameter and using the FT timing cover.."thats one I hadnt heard"

 

Snout is the term for the front of the crank where the spacer, damper and crank assembly slide onto?

I wonder if the rear of FE and FT cranks where it has that ring (don't know the correct term) with 6 bolt holes to bolt the flywheel onto, is it the same size, weight and bolt pattern for each?

Tyl

 

i would think there all the same ..and internally balanced....But I havent run one so?

 

The MD motors used the same timing covers the HD's did. The balancers were the difference here. Just use the MD balancer on the 428's snout to fit the FT's timing cover.

 

I've read the MD engine is a 360 FE. Same as the 360, even the crank but different interns. The timing covers may be the same, yet the HD does have its mounts on the sides of the timing covers onto an engine bay crossmemer, perhaps the MD aswell.

I am thinking I could use all the FE damper, pulley assembly. I might be able to use the FE crankshaft sproket, I would imagine the FT sproket is a bit larger, perhaps more teeth as well. The slinger and spacer would have to be combined.

Tyl

 

I know that my 391 FT is externally ballanced, don't know if the flanges are the same on the back of the crank, but balance may be different.