3U crankshaft

[djburton]

I have this 3U crank with 1 3/8 snout. From what I've read,it's an FT steel piece. Sounds exciting but since it would go into a car with a toploader, not really sure of the pitfalls. Balance,accessory brackets,pulleys....or should I dump it and find a car crank? It's a really nice standard crank and would probably stay that way if it's usable.   Thanks!

[pbf777]

         Dump it!   

         It costs to much to make into a usable unit, compared to that which is available in the marketplace already machined to fit properly.   

         Scott.

[cleandan]

         Dump it!   

         It costs to much to make into a usable unit, compared to that which is available in the marketplace already machined to fit properly.   

         Scott.

Scott, it's been a long time since I checked.
What is the cost to make the FT steel crank into a usable FE crank these days?
What is the cost difference between having the FT crank made to work as opposed to buying a quality new aftermarket crank that needs a little tweaking before use?

Both questions assume there are no extenuating circumstances requiring extra work and cost.

[fekbmax]

I wouldn't just dump it. Grease it up and bag it. Stick it in the corner of your shop. If you weren't so far away I'd make an offer myself. Shipping would be a killer on that beast though.

[frnkeore]

I'm doing that, ask we speak but, offset grinding it to SBC journals, as well.

You will have to have the snout turned down from 1 3/4 to 1 3/8. The center in the snout will not be on center of the main bearing, so it will have to be recut first. A machine shop will charge you about 3.5 hr labor to turn it and recut the keyways. I do that part myself. You will then have to open the flywheel to the FT diameter. Add another hr for that.

Offset grinding it costs a additional $600, including bearings.

[pbf777]

      And then you have nitriding, and then you have the balancing affair which will be more time consuming, maybe even requiring heavy metal (both equaling greater costing  ) than other options; are you adding this all up?  And it's still only probably a 1010 alloy, with a certain sum of fatigue already invested! 

      Yes, I hate the idea of a "chinese" crank, but if you at least buy from one of the better suppliers (pay a few dollars more!) they generally work out O.K..   

      Scott.

[frnkeore]

What I'm doing isn't cheap, I'm doing it for reduced rotating weight.

[1967 XR7 GT]

On the FT cranks other than the snout, the end flange is 3/16 longer, and should be cut down, to prevent any issues. I know 3/16 doesn't sound like a lot, but I was looking at running an automatic and torque converter clearance could be an issue for example. This is a heads up, as I see the FT crank brought up ocasionaly and all that's ever mentioned is about cutting the snout, and so there would an additional expense to have the flange cut.

[blykins]

      And then you have nitriding, and then you have the balancing affair which will be more time consuming, maybe even requiring heavy metal (both equaling greater costing  ) than other options; are you adding this all up?  And it's still only probably a 1010 alloy, with a certain sum of fatigue already invested! 

      Yes, I hate the idea of a "chinese" crank, but if you at least buy from one of the better suppliers (pay a few dollars more!) they generally work out O.K..   

      Scott.

I had Adney Brown work me up a 391 crank 5-6 years ago.  Did the snout work, did the flange work, turned the rod journals down to BBC size.  It was beautiful until it took about 8 pieces of heavy metal to balance it. 

[frnkeore]

In my case, I'm running a 164 tooth FW ring and a 3 disk, 7.5" clutch, with a button FW.

All different stuff that has to be reworked, into a package.

[GerryP]

I had Adney Brown work me up a 391 crank 5-6 years ago.  Did the snout work, did the flange work, turned the rod journals down to BBC size.  It was beautiful until it took about 8 pieces of heavy metal to balance it.

The application should always determine the parts specifications but if I was building an engine that wasn't under big boost, or not running with the throttle on the floor for three hours, I'd probably go with a good nodular crank and a good balance.  Less rotating mass, stiffer than forged, easier to balance, and the budget-friendly solution.  Everyone has their comfort zone.

[blykins]

I had Adney Brown work me up a 391 crank 5-6 years ago.  Did the snout work, did the flange work, turned the rod journals down to BBC size.  It was beautiful until it took about 8 pieces of heavy metal to balance it.

The application should always determine the parts specifications but if I was building an engine that wasn't under big boost, or not running with the throttle on the floor for three hours, I'd probably go with a good nodular crank and a good balance.  Less rotating mass, stiffer than forged, easier to balance, and the budget-friendly solution.  Everyone has their comfort zone.

Sometimes I have to work with what the customer sends/asks. 

[djburton]

I'm doing that, ask we speak but, offset grinding it to SBC journals, as well.

You will have to have the snout turned down from 1 3/4 to 1 3/8. The center in the snout will not be on center of the main bearing, so it will have to be recut first. A machine shop will charge you about 3.5 hr labor to turn it and recut the keyways. I do that part myself. You will then have to open the flywheel to the FT diameter. Add another hr for that.

Offset grinding it costs a additional $600, including bearings.

1 3/4 to 1 3/8? This crank is at 1 3/8 now. I'm confused...what's the diameter of a car crank snout?

[thatdarncat]

I'm doing that, ask we speak but, offset grinding it to SBC journals, as well.

You will have to have the snout turned down from 1 3/4 to 1 3/8. The center in the snout will not be on center of the main bearing, so it will have to be recut first. A machine shop will charge you about 3.5 hr labor to turn it and recut the keyways. I do that part myself. You will then have to open the flywheel to the FT diameter. Add another hr for that.

Offset grinding it costs a additional $600, including bearings.

1 3/4 to 1 3/8? This crank is at 1 3/8 now. I'm confused...what's the diameter of a car crank snout?

1 3/8” is passenger car/pickup truck size. The 3U crank is a cast iron pickup truck crank, not the forged FT crank. The forged FT crank snout diameter is 1 3/4”. Sorry.

[djburton]

Thanks,Kevin! the motor...and crank was lifted out of a 74 pickup,definitely 390,had 410 pistons,D4 casting,I think Dec,73 date. So...I'm back in business using the crank in a car without a bunch of mods?