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Carb / Vacuum issue [message #288553] |
Mon, 12 October 2015 10:33 |
bpimm
Messages: 211 Registered: June 2013 Location: Washougal Washington
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I'm starting a new thread to continue this discussion, was vacuum question. I was loaned a known good carb from a local GMC'er to test mine against. At idle mine was developing 16" of vacuum, dribbling fuel out of the primaries and running mostly in the 10-12 AFM area. After switching carbs idle now developing 19" of vacuum, not dribbling out of the primaries and operating in the 11-15 AFM area plus it runs a great deal better. the replacement carb is a little lean coming off idle and into the primaries under load it can bog a bit if you don't feather the throttle so it's not perfect but it is much better. it is idling at 14 to 1 and doesn't load up if it idles for an extended period.
So now we know that the carb is the problem. what should I be looking for on the tear down. History is carb was rebuilt by me 2 years ago but I had fuel problems, gunk in the tanks plugging the filter, this has been resolved by cleaning the tanks and replacing all the fuel lines, including hard lines. I had the top off of the carb a few weeks ago to check the float level and everything looked clean inside but I didn't tear it down any further.
Problems are low vacuum, fuel dribbling out of the primaries and little or no effect from the idle screws, which is probably from the excess fuel being pulled from the primaries.
I'm not a carb expert although I have rebuilt and tuned a few through the years, mainly Weber side drafts.
any and all help is appreciated.
Brian & RaeDean
1973 26' #383
Washougal WA
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Carb / Vacuum issue
By: bpimm on Mon, 12 October 2015 10:33
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Re: Carb / Vacuum issue
By: bpimm on Mon, 12 October 2015 11:23
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Re: Carb / Vacuum issue
By: bpimm on Mon, 12 October 2015 12:05
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Re: [GMCnet] Carb / Vacuum issue
By: USAussie on Mon, 12 October 2015 15:36
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Re: [GMCnet] Carb / Vacuum issue
By: bpimm on Mon, 12 October 2015 17:31
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Re: [GMCnet] Carb / Vacuum issue
By: bpimm on Tue, 13 October 2015 10:01
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Re: [GMCnet] Carb / Vacuum issue
By: Loffen on Tue, 13 October 2015 11:32
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Re: [GMCnet] Carb / Vacuum issue
By: USAussie on Tue, 13 October 2015 17:19
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Re: Carb / Vacuum issue
By: JohnL455 on Mon, 12 October 2015 16:24
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Re: Carb / Vacuum issue
By: bpimm on Mon, 12 October 2015 17:45
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Re: [GMCnet] Carb / Vacuum issue
By: k2gkk on Mon, 12 October 2015 18:00
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Re: Carb / Vacuum issue
By: JohnL455 on Mon, 12 October 2015 19:09
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Re: Carb / Vacuum issue
By: mercdave on Mon, 12 October 2015 19:44
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Re: Carb / Vacuum issue
By: bpimm on Mon, 12 October 2015 20:09
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Re: Carb / Vacuum issue
By: bpimm on Tue, 13 October 2015 14:07
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Re: Carb / Vacuum issue
By: roy1 on Tue, 13 October 2015 14:28
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Re: Carb / Vacuum issue
By: bpimm on Tue, 13 October 2015 14:59
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Re: [GMCnet] Carb / Vacuum issue
By: Kosier on Tue, 13 October 2015 21:07
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Re: Carb / Vacuum issue
By: mercdave on Tue, 13 October 2015 14:45
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Re: Carb / Vacuum issue
By: bpimm on Tue, 13 October 2015 15:17
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Re: Carb / Vacuum issue
By: Loffen on Tue, 13 October 2015 16:15
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Re: Carb / Vacuum issue
By: bpimm on Tue, 13 October 2015 17:38
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