1969 427 Alternator Belt Alignment

[Nick I.]

Hello everyone. I have another question to throw out for input from anyone who can assist me. I am in the final assembly stages on a January built '69 427 Tri-Power car and have run into a road block. When I disassembled the Vette, the incorrect belts were present and not laid out according to the manual. All of the original braketry was there. I have referred to the GM assembly manual for the proper belt layout and cannot get the alternator to align with the front groove on the power steering pulley. According to the manual, the alternator is supposed to align with the outer groove on the PS pulley. It does not. It will align with the inner grove, but then the belt layout would be incorrect. All of the brackets appear to be original and fit the vehicle well. I have also checked a service replacement alternator and it matches the unit I have exactly. Has anyone ever ran into this situation and what could be a possible cause and remedy?

Thank You,
Nick

[Dick W.]

Re: 1969 427 Alternator Belt Alignment

Is the pulley correct for your application??

[Jack H.]

Re: 1969 427 Alternator Belt Alignment

I agree with Dick! The most common reason for belt mis-alignment is substitute pulley replacement. Almost all factory original pulley's have their GM PN's stamped on them either on the front or the back side of the pulley.

Doing due diligence to compare, pulley by pulley, what you have to what the AIM calls out will often reveal a substitution error. That's one of the top reasons catalog houses selling reproduction belts get "doesn't fit" complaints from their customers.

So, that's the place to start in trouble shooting a belt fit/alignment problem...

[Kenneth T.]

Re: 1969 427 Alternator Belt Alignment

Nick,

Your BB alternator with ps should have a spacer on the pully that will move the belt forward to align it with the outermost groove on the ps.

Ken

[Nick I.]

Re: 1969 427 Alternator Belt Alignment

I verified the part numbers when the accessories were removed. As per the GM manual, all pulley's are correct. The car has a 2 groove crank pully, a 3 groove water pump pulley, and a 2 groove PS pulley. The rear most groove (closest to the motor) holds the WP belt. The next groove outward holds the PS belt that runs from the crank to the WP to the PS. I know the outermost groove on the WP is supposed to be for an A.I.R. pump which this car does not have. The only remaining groove for the alternator is the outermost groove on the PS pump as per the manual. I will look to see about the spacer on the pulley for the alternator.

The replacement alternator that I inspected yesterday had no spacer either and looked identical to what was on the car when it arrived at my shop. Is the spacer part of the pulley itself??

[Joe L.]

Re: 1969 427 Alternator Belt Alignment

I verified the part numbers when the accessories were removed. As per the GM manual, all pulley's are correct. The car has a 2 groove crank pully, a 3 groove water pump pulley, and a 2 groove PS pulley. The rear most groove (closest to the motor) holds the WP belt. The next groove outward holds the PS belt that runs from the crank to the WP to the PS. I know the outermost groove on the WP is supposed to be for an A.I.R. pump which this car does not have. The only remaining groove for the alternator is the outermost groove on the PS pump as per the manual. I will look to see about the spacer on the pulley for the alternator.

The replacement alternator that I inspected yesterday had no spacer either and looked identical to what was on the car when it arrived at my shop. Is the spacer part of the pulley itself??

Nick-----


The pulley should like like the one pictured below. The "spacer" is an integral part of the pulley.

[Nick I.]

Re: 1969 427 Alternator Belt Alignment

Thanks for the info. That is exactly what I need to put everything back to original. Thanks to all who posted replies to my questions. I'm sure I'll have a few more.

Thank You All,
Nick

[Michael B.]

Re: 1969 427 Alternator Belt Alignment

The one on the left is a tri-power with P/S pully. The one on the right is not correct for your application.