L78 crank pulley, need help, experience, opinions

[Too Many Projects]

Originally Posted by big gear head

What about putting a reinforcement plate inside the pulley? Would that prevent it from cracking? I'm using a standard groove original GM pulley on mine and shifting gears at 7200 RPM. Now I'm wondering if mine needs to be reinforced.

Freddie, aren't your pulleys formed steel ? The pulley for the swp is cast. I'm surprised you don't have belts flying off the standard pulley's. Maybe I'm OK with that too. I will definitely change out the alternator pulley for the deep one, as that seems to be the source of that belt coming off.
I'm not way north of 400 hp, but it is a healthy 496, so probably 550 ? Seems the L88 and modified L72's should have been more than that, back in the day. Did they have issues with the cast pulley cracking ? I guess most of the that stuff came out more after the introduction of the lwp in 1969 and formed steel deep grove pulleys.

[John Brown]

You were talking about cast pulleys? I was talking about the stamped steel ones cracking. Sorry if I misled you.

[Too Many Projects]

Originally Posted by John Brown

You were talking about cast pulleys? I was talking about the stamped steel ones cracking. Sorry if I misled you.

Yes, the part number I posted is for 1967-68 3 groove cast pulleys used with short water pump configuration. As far as I can come up with from research, they will work for 1965-66 also, but not correct part number.

[jeffschevelle]

Originally Posted by Too Many Projects

Yes, the part number I posted is for 1967-68 3 groove cast pulleys used with short water pump configuration. As far as I can come up with from research, they will work for 1965-66 also, but not correct part number.

3869978 is the correct original part number for all 65 Z16's (which all had PS), for all 66 L78's (regardless of whether the car had PS or not - if the car doesn't have PS then the third groove is just empty - don't ask me why they didn't use a 2-groove pulley), and for 67 L78's with PS.

[the427king]

Save your dust up and get an oem one....the gm pieces are not much more than the repo unlike the 291ab