Vacuum pump differences

[RLDSL]

What are the differences between early and late vacuum pumps. The listings show two different ones before and after 3/92
Thanks----Robert

 

[MIDNIGHT RIDER]

I have never ever seen but one basic design of belt-driven vacuum-pump, regardless of application.

The difference could be the pulley style, either serpentine, or A- or B-V-belt, or possibly the clocking of the hose-nipple.

Other than that, I would also like to know.

 

[THECACKLER]

The shaft is a different diameter and the two will not interchange.

 

[MIDNIGHT RIDER]

The shaft is a different diameter and the two will not interchange.

Meaning the bolt-pattern is also different ?? , or just that the pulleys have differing shaft sizes ??

 

[icanfixall]

I'll add this... The V belt pumps have the mounting holes threaded in them. The serpentine belt setups don't. The clocking of the vacuum nipple is differant too but you can make either one work on the other motors. I know nothing about the shafts being larger or smaller. I did use the v belt pump on my serpentine motor after I drilled out the mounting holes threads. The serpentine pulley fit it fine.... So now thats got some confused... any other imput....

 

[towcat]

I'll add this... The V belt pumps have the mounting holes threaded in them. The serpentine belt setups don't. The clocking of the vacuum nipple is differant too but you can make either one work on the other motors. I know nothing about the shafts being larger or smaller. I did use the v belt pump on my serpentine motor after I drilled out the mounting holes threads. The serpentine pulley fit it fine.... So now thats got some confused... any other imput....

that's good to know it can be done
thanks.
your next double-double up in my neck of the woods is on me

 

[LCAM-01XA]

The shaft is different between the Ford and the GM pumps IIRC, Hummers in particular.