Idle Problem

[Kenny Hancock]

I have a 67 L79 that has an idle problem. When I bought the car several years ago, it had a older 780 dual feed Holley that I replaced with a new 4160 Holley with an electric choke. It runs great, starts immediately in the coldest of wheather, and idles great at 750 rpm. My problem occurs after I have been driving the car for awhile. When I come up to a stop light and the engine speed drops back to an idle, sometimes it will die. Other times it doesn't actually die, but rather the idle speed varies from normal (750 rpm) to about 200 rpm and then back up to 750 rpm. If I give it some gas and hold it there for awhile, the engine will entually idle steadily at 750 like normal again. To make matters worse, this situation does not occur all of the time. Sometimes I can drive the car all day and it idles fine the entire time. The common theme I have noticed is that when it does happen, it is always after the engine has been running for awhile and is thouroughly warmed up. It seems to be worse on days when the ambient temperature is hot. One of the reasons I replaced the 780 Holley that was on the car when I bought was that it had the same idle problem. I thought I'd replace the carb with a more appropriate one, and solve the idle problem at the same time, but to no avail. The engine does not stumble at any speed, runs smoothly, and accelerates great through the entire rpm range. I checked the fuel bowls and the fuel level is correct. I was thinking the fuel might be getting too hot after the engine has been running for awhile am considering installing an insulated gasket. Any thoughts?

Kenny

[Clem Z.]

Re: Idle Problem

since you have a electric choke i would block the heatriser crossover in the intake to prevent the fuel from boiling. this will also had some HP

[Duke W.]

Re: Idle Problem

Check that the heat riser valve moves freely and is full open when the engine is fully warmed up. I would recommend blocking the valve open, but not blocking the cross over package.

Check your vacuum can for functionality. It should provide 16*@8" and be locked at full advance at idle. The numbers on the can should be "236-16" or B28. If it is other than this, replace the vacuum can with a NAPA/Echlin VC1810 (marked B28), which is the functional replacement for the original Delco "236".

Total idle timing should be steady at initial +16, which, for example, would be 26 if your initial is 10.

Duke

[Gary B.]

C2/C3 wheel balance weights

Hi Clem,

I've noticed from your NCRS DB postings over the months that you are an excellent authority on a variety of Covette issues. I'm hoping you might be able to answer a rather obscure question for me. Do you know with any certainty when the metric equivalent in grams began to be embossed on Corvette wheel weights? I'm researching facts for a story for my NCRS chapter newsletter and for subsequent submission to the Restorer and I think it would be a nice to add when the metric equivalent weight first appeared.

Thanks in advance,

Gary Beaupre
#28818

[Clem Z.]

Re: C2/C3 wheel balance weights

gary what i know about corvettes and there is some doubt about how much that is it is limited to between the front fenders and under the hood. these little details are best answered by the likes of john hinckley and others

[Joe L.]

Re: C2/C3 wheel balance weights

Gary-----

I don't think that the metric-embossed weights were ever used in PRODUCTION on any C1, C2, or C3.

I believe that the metric-embossed weights were phased into use from between 1986 to 1996 as earlier wheel weight part numbers were replaced by the GM #959XXXX series. For the configuration weights used on 1953-82 steel wheels, the SERVICE transition occurred in 1995-1996.