A.I.R. Emission Control System Diverter Valve: 1973 LS4

[George H.]

My '73 LS4 454 engine emisson control system pump is part number 7801149 date code 13032S (5/10/1973). The pump pully is stamped 330552DH. In checking the 1973-74 Second Edition Tech Manual, page 86, it does not show a part number for the 1973 LS4 Air Diverter Valve? The valve on the pump in my car is stamped 70344816. I can't see a date code and assume that is the correct part number. The engine assembly date is 3G6 7/6/1973. Looking to varify the diverter valve part number for a '73 LS4.

[Joe L.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

My '73 LS4 454 engine emisson control system pump is part number 7801149 date code 13032S (5/10/1973). The pump pully is stamped 330552DH. In checking the 1973-74 Second Edition Tech Manual, page 86, it does not show a part number for the 1973 LS4 Air Diverter Valve? The valve on the pump in my car is stamped 70344816. I can't see a date code and assume that is the correct part number. The engine assembly date is 3G6 7/6/1973. Looking to varify the diverter valve part number for a '73 LS4.

George-----

7801149 is not the part number for the AIR pump; it's the casting number for the backing plate used for several different pump models, including the pump used for 1973. However, given the stamped code, the pump is likely correct and original. The part number for the pump assembly, GM #7803948, usually appears nowhere on the pump.

Likewise, I believe the 70344816 is the identification number for a component of the diverter valve and not a part number for the valve. The part number for the diverter valve used for your application was GM #7029190. A derivative of this number, '29190' should be STAMPED on the valve near the valve's mounting flange.

Your GM #330552 pulley is correct for your application.

[George H.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

Very helpful informaton, thank you. Your comments should be added to tech manual.

[Jimmy P.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

Very helpful informaton, thank you. Your comments should be added to tech manual.

George,
Glad to see you brought this up and that Joe was able to answer your questions. We are currently in the initial stages of revising the 73-74 JG. I have had a note on page 86 of my JG noting the missing Air Valve LS4 info. Rest assured it will be addressed in the revision. Does your diverter valve have a round sticker on the front of it with the broadcast code letters 'JH' on it by chance?

[Leonard M.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

Pictures of the 29190 diverter valve. Identical to the 29199 and 29196. No evidence of a sticker on this one, but it may have come off.

[Joe L.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

Leonard------


Well, the valves are identical externally but not internally.

[James B.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

Leonard------


Well, the valves are identical externally but not internally.

Joe,

Would you elaborate?

James

[Joe L.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

Joe,

Would you elaborate?

James

James------

The valves have internal calibration differences to match the engine application they are designed for. This involves differences in internal springs, diaphragms, pistons, and passages. These cannot be discerned externally (except from the part number). For all practical purposes, a valve cannot be re-calibrated.

[George H.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

The pictures are very helpful. Looks just like the valve I have. I plan to take a closer look (need good lighting) and see if I can ID the part number under the mounting flange. Also, I don't think the valve still has a sticker on it but I will look again. I'll post a thread as to what I find. Thanks again.

PS. I purchase the car in Gainesville FL in 1980 from a good friend who purchased it in Jacksonville, FL. Its Yellow Metallic 953 and never been painted!! Needs a new front bumper cover. Working on getting everything working so it can be judged. I have most of the original purchase documents including the new vehicale inspection procedure GSDF 99 Rev.4/72 signed 8/2/1973 by Gene, technician 33, E.F. Connell Chevrolet. I also have the original warranty booklet when purchased off the showroom floor (9-18-73) and Divison of Florida Higway Partrol Vehicle Safety Inspection showing 12 miles on the odometer. Probabily still has the build sheet on the gas tank. ? Florida car 1YZ37 LS4 coupe with factory AC, M21 4 speed, AX 3:36:1 rato,power breakls, power steering, power windiows. AM/FM radio, 404 customer leather interior and had GR-70-15B WS Firestone "500" radial tires when delivered new. Tires replaced P21 recall notice done 7/12/1980, Gainesville, FL. Mileage is currently 72,768.

[Leonard M.]

Re: A.I.R. Emission Control System Diverter Valve: 1973 LS4

Thanks Joe, I figured they would function differently, but wasn't really sure. Why assign different part numbers to identical looking parts from the same era.
If anyone was curious, here's a 29192 valve (69-70 Cadillac?) where I removed the muffler. The brown material in the muffler is like a thin layer of scotch brite.