C3 A/C Fan Motor Speed

[captras]

About a year ago...maybe longer, there was a thread that discussed replacing the fan motor on a 75, or any C3 with a C4 fan motor. It gave instructions and a template to use to make a spacer for the replacement motor. Anybody have that info, or know where it is?

Thanks

 

[dk1977]

About a year ago...maybe longer, there was a thread that discussed replacing the fan motor on a 75, or any C3 with a C4 fan motor. It gave instructions and a template to use to make a spacer for the replacement motor. Anybody have that info, or know where it is?

Thanks

I found this on Eckler's. I replaced my '77 fan with this setup and got maybe 20% more air. You can actually feel it blowing from the center vent while seated.
Good luck.
DK
"NEW INFO
First I just replaced the original motor with a replacement and used the same impeller. I put everything back together, duct taped the joints, foam sealed everything and still only had a little air flow. I then bought a blower and impeller from Autozone for a 1995 Vette. ($45) The impeller is bigger, more blades, steeper angle and they are slightly twisted.

I had to fabricate a spacer for the new impeller to fit into the housing because is is about 1.5 inches longer. The motor mounts the same. I made two rings of pressboard, glued them together, sealed them and painted them black. I then sealed them to the housing and mounted the motor to them.
When I got everything back together, I tested the air flow and put vacuum to the source and holy cow I have real air flow. It actually blew the papers off the seats.

I still haven't hooked up the AC yet, but my first goal was to get air flow. Now I can concentrate on getting it cold.
I'll get some photos when I get a chance.
Thanks to everyone that helped with the vacuum lines. I'd also definitely recommend that AC book if you are struggling like I was to get the air moving.