View Single Post
Old 08-07-2019, 11:58 AM   #99
mattfranklin
Senior Member
 
mattfranklin's Avatar
 
Join Date: Dec 2011
Location: Moraga, CA
Posts: 808
Re: PROJECT: How would a Chevrolet dealer build a shop truck in the early 1970s?

I'm so lame on pictures. Anyway, here's what I was doing recently...

I was having trouble making it idle at a reasonable rpm. Every time I tried to dial down the rpm I'd get a stumble, stumble, stumble and then it would die. I was assuming that my almost new (in actual running hours) carb was damaged from backfiring or years of old gas sitting in it and occasionally running through it.

Yesterday while I was fiddling, and the engine was warm but had just died, I noticed a plume of vapor rising from the back of the carb. And it kept going. I was worried I had a little fire and that the plume was smoke. When I was able to crane my neck and see, I saw that there was a 3/8" uncapped port under the rear fuel bowl. Doh! Massive vacuum leak. No wonder it wouldn't idle! I could not believe it! #1 that I was so absent minded to have missed it for so long, and #2 that I was so lucky to have finally found it today.

Bottom line, I capped it and readjusted the idle mixture screws (about 1-3/4 to 2 turns on the primaries and 1 the secondaries idle was about right to make it smooth) and reset the idle speed and now it runs great. Now I just need to install shocks, hood latch, add insurance, and register it as operational and go for a real road test.
__________________
(Very) Slow-Going Build Thread: Stock 1970 Short Step with Stock 1970 LT-1

http://67-72chevytrucks.com/vboard/s...d.php?t=567340

Last edited by mattfranklin; 08-08-2019 at 07:56 PM.
mattfranklin is offline   Reply With Quote