[michaelroy]

I have had my car 65 LeMans 10-12 years> It has a 66 Big car 092 389. Recently, the power steering is ineffective at low rpm's. If I rev engine the power returns. So I have made no changes to the set up in 7000 miles.
Problem would seem to point to pulley size. But since I haven't made and changes i am stumped.

[Dick Boneske]

You may want to change the pressure relief valve in the pump. It is accessible at the high pressure hose port. Later years used a different spring./spool setup and may not work properly with the older steering box--or, if you have a later steering box, the original pump pressure control may not work.

[tempest1964]

A guy named Jim Shea wrote an excellent article on this subject. I found this article on the Chevelle forum. https://www.chevelles.com/threads/up...#post-11389060
And this too: http://jimshea.corvettefaq.com/wp-co...s-09OC2013.pdf

[John V.]

Obviously you would want to check proper fluid level.

And also check for any leaks or a pressure hose that has degraded.

I'm guessing Dick has pointed you to the likely culprit.

Check this article for relief valve diagnosis.

https://benchworksteering.com/tech-t...-relief-valve/

[Geoff]

If it worked before, why would the pulley size be an issue now? Check the pressure relief valve & spring behind it as described in post #2.

[OG68]

I had a similar problem; After removing the valve and spring, do a complete fluid flush of the pump and gear. The clearances between the valve and the pump bore are extremely tight. Doesn't take much in the way of dirt or other debris to cause the valve to stick.

[michaelroy]

Thank you Gents for this information. Now that I know what the issue is, I can proceed. Probably have a better wrench turner than my self to fix.
Thanks again.......Michaelroy