High altitude distributor

[king80vette]

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

 

[Vettehead Mikey]

It's really tall?:crazy

Sorry, couldn't resist. You sure you don't mean high altitude carb?

 

[king80vette]

If you don't have any usefully information don't say ANYTHING!!!:eyerole

 

[Vettehead Mikey]

Umm, no I wasn't joking about the high altitude carb.

This was a common 'feature' of cars that were sold in the higher altitude parts of North America, such as Denver. The carb was jetted differently to compensate for the thinner atmosphere. 1977, 78 and 79 Corvettes had specific parts number for high altitude carbs. Perhaps the distributor was recurved on later cars also (more advance sooner?) but this seems to be unique to 1980. Your distributor carried a unique part number (1103353).

Gauging by the amount of responses, not many other people are familiar with this feature.

 

[king80vette]

Thanks for the information and I’m sorry for the remark above. It’s just that I’m getting frustrated with this car. I’ve been working on it for 3 1/2 years. Two weeks ago it received top flight from the NCRS and I’m happy about that.

But the problem is it just will not idle well. Now I’m not asking for perfect idling just decent. The distributor does have the part number you mentioned. I can’t get the timing set. As I get closer to the correct setting the engine runs worse. So I set it where it runs the best. I’ve turned the idle mixture screws in and out so many times I think I’m going to ware out the threads. Was the high altitude distributor listed as an option on the build sheet or order form? I have both of these documents. The car was delivered to Pennsylvania in 1980 and has always been in Pa. Is there a way I can check to see if it was recurved? Maybe someone replaced the original distributor with this one. Is there a way to check if the carburetor is jetted properly? It seams to be running lean because the spark plug insulators have a red look to them.

Any help with this issue is appreciated and again sorry for the bad attitude.
Steve

 

[pgtr]

Steve, I can't offer any specific solutions as I'm not familiar with your specific model. But I've found GMs of the early 80s with age and miles on them to be problematic at times with respect to things like a decent idle. In some cases I've traced this to early electronic (or computer?) emissions controls combined with old school carb and ignition. E.g. electronic controls on carbs and O2 sensors electronically controlled distributor advance and what not... just some possible ideas to consider...

 

[lucky76]

If you don't have any usefully information don't say ANYTHING!!!:eyerole

You'll have to admit, that was funny!

 

[JohnGrawcock]

Steve, I can't offer any specific solutions as I'm not familiar with your specific model. But I've found GMs of the early 80s with age and miles on them to be problematic at times with respect to things like a decent idle. In some cases I've traced this to early electronic (or computer?) emissions controls combined with old school carb and ignition. E.g. electronic controls on carbs and O2 sensors electronically controlled distributor advance and what not... just some possible ideas to consider...

The 80 doesn't have an ECM. The computer controlled carb was only on the 81.

 

[JohnGrawcock]

Thanks for the information and I’m sorry for the remark above. It’s just that I’m getting frustrated with this car. I’ve been working on it for 3 1/2 years. Two weeks ago it received top flight from the NCRS and I’m happy about that.

But the problem is it just will not idle well. Now I’m not asking for perfect idling just decent. The distributor does have the part number you mentioned. I can’t get the timing set. As I get closer to the correct setting the engine runs worse. So I set it where it runs the best. I’ve turned the idle mixture screws in and out so many times I think I’m going to ware out the threads. Was the high altitude distributor listed as an option on the build sheet or order form? I have both of these documents. The car was delivered to Pennsylvania in 1980 and has always been in Pa. Is there a way I can check to see if it was recurved? Maybe someone replaced the original distributor with this one. Is there a way to check if the carburetor is jetted properly? It seams to be running lean because the spark plug insulators have a red look to them.

Any help with this issue is appreciated and again sorry for the bad attitude.
Steve

Have you checked all the basics? Here are a few thoughts. I have no idea what your level of expertise so don't be offended if they are things you have already looked at.

* Did you disable the vacuum advance prior to setting the timing?
* Do you have any vacuum leaks? Don't forget to check the EGR and brake booster.
* The idle mixture screws only set the idle fuel to air ratio. There is little reason to ever set these screws to anything but the default setting. If I remember correctly, the norm was to turn these screws all the way in and then back them out one and a half turns. The procedure can be found in most basic repair manuals such as Haynes or Chilton's (spelling?)
* Is the idle speed set correctly? The emissions sticker in the engine compartment should tell you the specified RPM. The idle speed is set by a stop screw on the throttle plate rod near where the throttle linkage attaches to the carb. Simply turn this screw in or out until the tach reads the specified RPM.
* Is the ignition timing stable? If the timing is jumping around excessively the bushings in the distributor may be worn.
* You can check the operation of the vacuum advance by attaching a vacuum pump to it and using a timing light to watch the timing change as you draw a vacuum.

 

[Vettehead Mikey]

One more thing- is the timing mark on your balancer accurate?

 

[king80vette]

I have checked some of these things and will look at the rest. I do disconnect the vac advance and plug it when adjusting the timing. I can not get the idle down to the recommended setting because the engine shuts off. I did hear that the balance could be off because of the gasket.

Thanks for the help.
Steve