[michaelroy]

Good Morning guys. Hope every one is safe and healthy.
I have a 65 gto clone with a 389 tri power with a/c. All of my belts seem to be taught with no sagging problems. However, when my rpm's get low my power steering is not operating as it should. No issues with steering when up to speed.
Any suggestions?
Thanks Mike

[Dick Boneske]

The a/c-equipped cars have a larger pulley on the power steering pump, which obviously results in the pump running at a lower rpm than non-a/c cars. I don't know how we'd find out, but maybe the a/c cars had a different pump than non-a/c cars--possibly with more displacement.

I don't know, but is it possible that the a/c cars used a larger pulley on the harmonic balancer, resulting in higher rpm for the pump? I guess looking at the '64 Chassis manual exploded view of the a/c belt system would help.

[Chris65LeMans]

It it making noise? Fluid level OK?

[RA1John]

'65 T/8 used different Pulleys for A/C applications...
- Crankshaft/Harm. Balancer
- Water Pump
- Power Steering Pump

Originally Posted by Dick Boneske

The a/c-equipped cars have a larger pulley on the power steering pump, which obviously results in the pump running at a lower rpm than non-a/c cars. I don't know how we'd find out, but maybe the a/c cars had a different pump than non-a/c cars--possibly with more displacement.

I don't know, but is it possible that the a/c cars used a larger pulley on the harmonic balancer, resulting in higher rpm for the pump? I guess looking at the '64 Chassis manual exploded view of the a/c belt system would help.

[Geoff]

From the resto guide.

Original A/C & P/S: 8 5/16" crank pulley & 7 3/8" p/s pulley.

Non A/C cars: 7 1/4"crank & 5 7/8"p/s pulley.

The p/s should be slightly overdriven

[michaelroy]

The restoration guide has a diagram but states it is incorrect. Does anyone have a correct diagram? The engine is a 66 big car 389 w/ 092 heads and I have the tri power that Dick B assembled.

[John V.]

I don't recall that the Resto Guide says the diagram is incorrect. Generally, the Guide simply copied diagrams from various Master Parts Catalogs. Perhaps you mean the Illustration? These were also usually copied from the MPC but perhaps the detailing was incorrect for '65 as perhaps the Illustration is specific to a '64 and only generally typical for a '65?

Doesn't really matter. You say yours is a '65 clone but with a '66 Engine.

Do you know if the Accessory drive set-up is from the '66 or is it made to duplicate a correct '65 arrangement?

I'm not familiar with either year but there is a significant difference between the two when equipped with A/C and PS. '65 used a single belt to drive the Alternator and the PS Pump. In '66, PMD went to a 3 groove Balancer pulley for A/C with separate belts, one each to drive the A/C compressor, the PS Pump, and the Alternator.

If it is a '66 set-up, does it include A.I.R. (air pump for emissions)? That would add more complexity.

Assuming you want to copy a '65 set-up, here is what you should have:

1. Balancer would be p/n 9781740. It has a 2 groove pulley. I'm not familiar with it. It does include an 8-5/16" dia. but it should be similar to the '64 A/C Balancer, the front groove drives the A/C Compressor and is a smaller dia. than the 8-5/16" dia. rear groove.

2. The larger dia. rear groove of the Balancer (crank) pulley drives the Water Pump, Alternator, and the PS Pump using a single belt. The belt is 1/2" x 56-1/2", p/n 534312. The Gr. parts list says the belt is actually 7/16" although another application for the same belt says it is 1/2". So either the parts list contains a typo or possibly the original factory installed belt was 7/16" but later revised in production or just for service to the 1/2" but the description was not properly revised.

3. The Water Pump pulley is p/n 9781739. It is 2 groove, both belts spin the Water Pump. The rear groove is 7-3/8" dia. and aligns with the pulleys for the Alternator and PS Pump. The front groove is smaller dia., I do not know the dimension but it aligns with the A/C Compressor pulley.

4. The PS Pump pulley is p/n 9779020. It is single groove, 7-3/8" dia.

5. The Alt pulley is p/n 1949355. It is single groove, 2-1/2" dia.

If your set-up is different than what I've listed and described, it would be useful if you described it and listed the pulley dias. (stamped p/ns would be even better).

Conceivably your pump output pressure is too low due to internal leaking. You could consider checking the output pressure to see if it is within spec. I didn't check but I think the pressure spec would be in the Shop Manual.

But if it is just a matter of the pump rpm being low at low engine speed, it could be the wrong combination of pulleys so first step would be to check them.

[389]

Pull the flow valve from the pump and see how many washers is on it. I usually only use one...

[tempest1964]

X2 on that 389. There is a guy named Jim Shea that is very well versed on this subject. I am attaching a link to a piece he wrote on modifying a Saginaw power steering pump for greater pressure and flow.
http://jimshea.corvettefaq.com/wp-co...s-09OC2013.pdf

[michaelroy]

Thank you gents for the replies. It is much appreciated. I'm pretty sure the crank pulley is the one used on non A/C cars. I have the correct pulley on the 326 engine I have.