Stock crank pulley diameter?

[Todd]

Anyone know the diameter of the stock crank pulley?

Not the outside of the puller/dampener but the inside where the belt rides.

I wanted to try some different alternator pulley diameters in a calculation to see what the shaft rpm will be at various engine rpm's.

[Raudermaster]

Todd dude when are these videos going to be rolling out?! I can't wait any longer.

[Joe Walsh]

I'll dig mine out of a box in the garage and measure for you when I get home from work tonight.

(I'm thinking 6-1/2"...:dunno:.. I measured the OEM dampner to compare it's size to the UDP that I installed several years ago.)

[magindat]

:bump:

I'd like this info as well.
Thanx!

[Joe Walsh]

I just measured my OEM crank balancer/pulley.

My memory is still pretty good!

The OD of the serpentine belt grooves is 6-9/16".

[Todd]

I just measured my OEM crank balancer/pulley.

My memory is still pretty good!

The OD of the serpentine belt grooves is 6-9/16".


Thanks Joe, I appreciate you checking on that for me (and anyone else interested).



EDIT - I did the calculations on our crank pulley with what I think is the alt pulley size and it looks like we spin ours dangerously close at max engine rpm.

I used the calculator on the paperformance site. 6250 max engine rpm with 6.6 crank pulley and 2.25 alt pulley size equates to over 18k alt shaft rpm at max engine rpm. Not like you are going to stay there long in most cases but pa says 16k is a safe limit to shaft rpm. Stock shafts can take more rpm due to greater air gap. But the higher performance alternators shouldnt be run that high because of closer tolerances.

Looks like I need about a 2.75 alt pulley to be safe at around 6800 max engine rpm and still produce a good alt shaft speed at idle (900 engine rpm = 2100+ alt shaft rpm).

I need to verify the clutch pulley diameter. I was going off an estimate on the size of 2.25.