A.I.R. Diverter valve

[Bryan M.]

Hello,
I have a diverter valve with the part number 7034481. The end cap on the valve has a underlined DH stamped with black ink on it. It has a L-shaped rubber hose with the GM [] 3917648. The tower hose clamps have 1 1/4 4/67 stamped on them.
The muffler has SCHMELZER stamped on the backside and it's staked on in two places. The 68/69 judging manual states the DH means 68 327, hose is for a 68 with 327, the clamps seem to be in the right dates for a 68 with 327, the muffler is staked as the 68 AIM describes. The 68 AIM calls for 7028469. The 68/69 judging manual reports several other numbers have been reported. Could this be one of those other 68 diverter valve part numbers?

[Joe L.]

Re: A.I.R. Diverter valve

Bryan-----

First of all, 1968 Corvette diverter valve silencers (mufflers) were NOT staked to the body of the valve. They were retained by a "horseshoe" clip and are removable. 1969 diverter valves, except L-88/ZL-1, had the silencer staked to the valve body. The L-88/ZL-1 configuration was just like the 1968 configuration.

Second, diverter valve part numbers are NOT stamped anywhere on diverter valve assemblies, although a 4 digit derivative of the part number is STAMPED on some valves. If the numbers that you are referring to are RAISED numbers, that's just the part number for one of the components of the valve assembly and does not identify the valve.

[Bryan M.]

Re: A.I.R. Diverter valve

So, the 68 AIM assembly manual is wrong? On page UPC 6 C4 view B note To be staked securely( 2) places at asm. It also has this same info on page UPC L36 A4. Could not find any info in AIM for a horseshoe clip.

[Bryan M.]

Re: A.I.R. Diverter valve

I broke out the magnifying glass and indeed found the numbers 28469 stamped on the valve. The numbers are located on the flat side of valve where the rubber elbow is attached.

[Terry M.]

Re: A.I.R. Diverter valve

I know my 1970 LT1 has the diverter valve part number stamped on it, and other diverter valves I have seen also have the number stamped on them. It is one of the best ways to tell what the application of the valve is when it is loose from the box.

[Joe L.]

Re: A.I.R. Diverter valve

Terry-----

I have never seen a diverter valve with the complete part number stamped on it. However, as I mentioned previously, most diverter valves do have a derivative of the part number stamped on them. This consists of the last 4 or 5 digits of the PRODUCTION diverter valve part number. Early SERVICE valves, although they often had a different part number than the PRODUCTION valve, had the same part number derivative as the PRODUCTION valve stamped on them. These stampings are small and lightly stamped on the main body of the valve.

The number that Bryan provided in his original post was a complete part number and for that and other reasons could not be the part number of the valve assembly. Among the other reasons is the fact that there never was any diverter valve of that part number ever manufactured.

[Joe L.]

Addendum

I should have said that I have never seen diverter valves from the 68-73 era with the complete part number stamped on them. Much later SERVICE diverter valves with plastic valve bodies and metal covers usually have the complete diveter valve part number stamped on the metal end cover. However, these valves were never originally used on any C3.

Some of the all metal valves originally used on 74-82 Corvettes may or may not have had the complete part number stamped on the valve.

[Joe L.]

Re: A.I.R. Diverter valve

Bryan-----

"28469" is the correct part number derivative for the 1968 327 diverter valve.

As far as the AIM is concerned, I'm not sure that it accurately reflects the actual diverter valve configuration for the 1968 valve or, at least, the configuration used for the whole model year. All of the 1968 diverter valves that I have seen use a silencer which attaches to the valve with a "horseshoe" clip, with no crimping, at all. In fact, I have several NOS examples of the 427 diverter valve [none for sale] with the original "28296" part number derivative and "DC" broadcast code. All of the valves that I have use the "horseshoe" clip for attachment of the silencer assembly even though the AIM also shows the valve for the 427 with the "crimped" silencer attachment.

Some of the information which I have indicates that the 3918966 silencer, shown in the 1968 AIM, was never actually used for a Corvette application. Instead, they show that the GM #1492575 silencer was used for the Corvette application. This silencer uses the "horseshoe" clip attachment; I have several of these in NOS form [none for sale] and all are of the "horseshoe" clip attachment. The GM #3918966 silencer was discontinued from SERVICE in January, 1968 and replaced by the GM #1492575 silencer.

I suppose it's possible that some, or perhaps all, 1968 Corvettes did receive the 3918966 silencer and it's possible that this silencer did use a crimp style attachment. It would be interesting to hear from someone with a known-original 1968 with 327 regarding the configuration of the silencer attachment on their diverter valve.

[Bryan M.]

Re: A.I.R. Diverter valve

Thanks Joe,

It would be nice to hear from someone with a known original.

[Ed Rosen]

Re: A.I.R. Diverter valve

I am the 4th owner of a 68 372/300 and have spoken with all of the previous owners, who have all told me the smog pump on my vehicle is the original from the factory. They also have provided me with the original window sticker, bill of sale, protect-o-plate, warranty book and owners manuals, showing they were very honest and forthcoming with info on my vehicle. With that said and using the AIM (page 193) for reference, the full part number 7034481 is stamped (raised) on the diverter valve on the section where the two hoses attach (facing up). Also, on the main body of the valve, opposite of the muffler (between the pump and valve is a raised GM, Made in U.S.A stamp. As for the way the muffler ASM attaches, I am unsure since the one on this system is fell off this summer. However, the way it attaches looks nothing like what is displayed in the AIM on page 193. The muffler seems to attach by being pinned over a 1 7/8" X 1 3/8" opening. The reason I say pinned is, there is two depressions on both of the two longer sides, closest to the cap (away from the hoses. I am looking for a replacement muffler if anyone knows where I can locate one.... Hope this does not add more confusion to the situation...

Ed.

[Bryan M.]

Re: A.I.R. Diverter valve

Ed,
Thanks for replying back. From your description it sounds to be just like my valve. My muffler slips into the valve body and has two punched impressions (staked) through the valve body, opposite of each other that holds the muffler in place. I'm not 100% certain but this diverter assembly appears to be a original take off.