C3 high altitude distributor

[Steve King]

My 1980 has a high altitude distributor on it. What's different about this distributor that makes it a high altitude?
Steve

[Duke W.]

Re: C3 high altitude distributor

Probably the ignition advance map. It may also have a different carb number with slightly different calibration. Call GM cust. service 1-800-222-1020 and ask for the 1980 restoration package, which should include the AMA specs that will have details. The service manual should also list advance maps.

They will want the VIN.

Duke

[Steve King]

Re: C3 high altitude distributor

Thank you for the information.
Steve

[Steve King]

Re: C3 high altitude distributor

Duke,
Do you know if the high altitude distributor is on the build sheet or order form?
Steve

[Duke W.]

Re: C3 high altitude distributor

High altitude engines should have a unique broadcast sheet code that I think was triggered if the ordering dealer was located at 4000 feet or more altitude. High altitude engines had specific components - dist and/or carb or other devices, so they would have to have unique codes.

Details of the differences should be in the service manuals and AMA specs.

High altitude is not an issue on modern engines with O2 sensors as the mixture is maintained at stoichiometric (except WOT) regardless of inlet air density.

Duke

[Tom R.]

Re: C3 high altitude distributor

Steve:

I don't have the exact 1980 specs...but don't believe high altitude motors were equipped on Corvette in 1980 as they were in previous years. Now having said that the engine suffix code (also engine broadcast code) would be called out on the build sheet but the distributor code would not be called out on the build sheet...its installed at the engine plant and is a part of the engine assembly. The carb type is called out on the build sheet. So you can triangulate the three and determine if the configuration is correct for the Corvette model in front of you. The GM restoration lists the specs for the various engine models equipped for that given year.

Carb code is on the driver's side, distributor code (and part #) is stamped on the housing and you probably have the engine suffix code from the stamp pad.

[Joseph T.]

1976

See below

[Michael W.]

Tom, we've already established

(in a string on another web site) that the dist. on Steve's car is a bone fide high altitude part number for a 1980 L-48 Corvette. The mystery is this car is an original 'low-lander' car, accompanied by poor idle characteristics.

[Joe L.]

Re: Tom, we've already established

Mike and Steve----

What is the distributor part number for the car?

[Steve King]

Re: Tom, we've already established

The part number is 1103353. What I'm trying to find out is did this car come with this distributor or not. Then do I need to do something to it for opperation at lower altitude. The car idles poorly and has for the 3 years I'v had it. The second part is should the carb be re-jetted? The spark plug insulators have a red look to them.

Steve

[Michael W.]

Re: Tom, we've already established

1103353, as shown in the NCRS pocket spec guide for 1968-82. Seems to be a unique to 1980 feature. Previous years called out a high altitude carb.

[Joe L.]

Re: Tom, we've already established

Steve-----

The GM #1103353 distributor was used for high altitude applications. However, that usage was for the 1979 model year. For the 1979 model year, it was used not only for the L-48 with high altitude emissions, but also for other non-high altitude emissions applications.

For the 1980 model year, I can find no information that would confirm that a high altitude emissions configuration actually existed. For the 1980 model year, the GM #1103353 distributor was used for all L-48 with auto trans applications.

One of the "key features" of high altitude emissions system configurations is a specially calibrated carburetor. Indeed, for the 1979 model year a specially calibrated carburetor was used for high altitude applications. This carburetor was known as GM #17059582.

For the 1980 model year, all L-48s with auto transmission used carburetor GM #17080204. This is the carburetor that should be on your car if it has the original carb. So, not only was there no special distributor applicable to 1980 with high altitude emissions, there was no carburetor applicable to high altitude emissions, either. That pretty much rules out that there was such an emissions system for 1980.

I would say that any problems with "rough running" that you are experiencing are most likley due to some deficiency with the carburetor than they are to an ignition system deficiency associated with the distributor.

[Clem Z.]

difference between high alt and std carb

the std 350 1979 corvette carb uses #72 jets and #40 rods and the alt carb #17059582 uses #71 jets and #41 rods so the alt carb is leaner all thru the range. if you have the 17059582 carb i would try the other jet and rod combo. the 17059582 carb was used on both 350 and 305 cu in altitude chevy engines used across the GM car lines,buick,chevy,olds and pont

[Steve King]

[Joe L.]

Re: Tom, we've already established

Steve-----

Yes, you have the correct distributor and carburetor that should be on your car. This does not mean, of course, that they're both functioning properly, but they are the correct parts that should be on it.