COPO Feature

[676767]

I have been reading a lot of posts from various web sites and in almost every instance there is a mention of the proportioning valve on the sub frame being an important feature. Is this a COPO feature or a BIG block SS feature or did they both have this.

When I renewed my brake system I took that system off because fo the condition ofthe valves and when with a more modern system, is this a major issue for value or minor compared to the drive line authenticity???

[William]

Disc brakes require far more PSI than drums. The valve, fully explained in a Chevy Dealer Service Bulletin Nov 69, limits pressure to the rear brakes to prevent lockup. The Delco Brake Service Manual states that some disc masters had an internal valve in the rear brake line port, perhaps explaining why some disc brake cars don't have the valve on the frame. The first mention of the frame valve is in 1967 Camaro info, stating that cars with A/C would use it.

The frame valve has nothing to do with Hi-Performance engine options. Many early production disc brake '69s don't have it.