A/C Schrader Valve Cap

[Martin N.]

I'm going to be getting caught up on alot (about a 2 page list) of the smaller details / items over the winter months for possible 2009 summer judging and was wondering about this cap. The 1973-74 J. G. calls out a "Brass Hexagonal Cap" for the compressor a/c manifold block. The one on my 1974 L-48 car is a "Brass Round Cap". See photo. How much of a point deduct can I expect for the difference in shape? Should I hunt for a hexagonal one? THANKS.

Marty

[Harmon C.]

Re: A/C Schrader Valve Cap

I would say that cap would be one point or even part of two things to make a point. If you have old junk yards with 70's GM cars you may find one. A local person who has serviced A/C cars forever may have one in their junk box.

[Peter L.]

Re: A/C Schrader Valve Cap

Marty - I know earlier, i.e. 63-67, Corvette A/C compressor mufflers used the hex-brass Schrader valve cap and a round-brass Schrader valve cap on the STV and POA valve. Many times I've seen the caps in the opposite location because if the unit required charging the caps had to be removed, and on reinstallation since the caps will fit either valve, there is a 50-50 chance they will be installed back on the valve they came off of, unless the person servicing the unit was anal, like a NCRS Corvette owner.

I'm not familiar with the plumbing on any of the newer A/C systems, but if there is a second Schrader valve, you might check and see what cap is on that valve and you just might luck out or you'll have to make that executive decision if you're going to look for a hex-brass Schrader valve cap.

Have fun.

Pete

[Gerard Q.]

Re: A/C Schrader Valve Cap

I'm going to be getting caught up on alot (about a 2 page list) of the smaller details / items over the winter months for possible 2009 summer judging and was wondering about this cap. The 1973-74 J. G. calls out a "Brass Hexagonal Cap" for the compressor a/c manifold block. The one on my 1974 L-48 car is a "Brass Round Cap". See photo. How much of a point deduct can I expect for the difference in shape? Should I hunt for a hexagonal one? THANKS.

Marty

I was recently looking for the same caps....most parts houses list them but I found only Corvette Central actually has them in stock.

"AIR CONDITIONING MUFFLER FITTING CAP - BRASS HEX ORIGINAL"
Part # 452078

[Terry M.]

Re: A/C Schrader Valve Cap

I don't have a 1973-74 TIM&JG handy, but on 1968-1972 Corvette (and other GM carlines of the time) AC systems the brass hex-shaped cap is tin plated. Last time I looked the TIM&JGs for 1968-1972 called for this plating.

[Jack H.]

Re: A/C Schrader Valve Cap

That's been a sporadic problem...descriptive text discloses the composition of this/that part, but fails to talk about the actual finish! In this case, the A/C valve caps WERE made from brass, but they were 'color coordinated' to the aluminum manifold below by being zinc/cad/tin plated.

I've seen more than one owner put a car on the field with BRIGHTLY polished brass caps bursting with pride on how long it took them to polish off the silver colored 'residue' that they found on their originals!