C3 Backfiring / Idling Low
Thread Starter
Safety Car
Joined: Mar 2002
Posts: 4,366
Likes: 7
From: Las Vegas NV
C3 Backfiring / Idling Low
My '70 350 / 350 is idling really low and is stalling out when I don't give a small amount of gas. It's also backfiring when I'm trying to get it started. Is this caused by the timing being off?
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
Re: C3 Backfiring / Idling Low (Motor City Vette)
Sounds similar to what I am going through. I have not determined my problem yet, but think the timing chain jumped a tooth.
Mark B.
Mark B.
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: C3 Backfiring / Idling Low (Motor City Vette)
Motor City Vette:
Where you at in Detroit?
On your problem: Might be vacuum related. I picked up 1.5 lbs of vacuum today by finding one of my vac accessories' line was off. It also cured my slight hesitation and backspit ( not big as a fire) problem.
Where you at in Detroit?
On your problem: Might be vacuum related. I picked up 1.5 lbs of vacuum today by finding one of my vac accessories' line was off. It also cured my slight hesitation and backspit ( not big as a fire) problem.
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: C3 Backfiring / Idling Low (Motor City Vette)
If you just changed plugs or wires or worked around them, there are two wires that when crossed will give you those symtoms. Check the firing order carefully.
Thread Starter
Safety Car
Joined: Mar 2002
Posts: 4,366
Likes: 7
From: Las Vegas NV
Re: C3 Backfiring / Idling Low (silvervetteman)
Fevre,
I'm just north of Detroit in Rochester Hills. You're in Ann Arbor? Very nice, I used to live there. I grew up going to UM football games and still make it to most home games with 111,000 of my closest friends. Great town.
[Modified by Motor City Vette, 11:14 PM 4/1/2002]
[Modified by Motor City Vette, 1:26 PM 4/2/2002]
I'm just north of Detroit in Rochester Hills. You're in Ann Arbor? Very nice, I used to live there. I grew up going to UM football games and still make it to most home games with 111,000 of my closest friends. Great town.
[Modified by Motor City Vette, 11:14 PM 4/1/2002]
[Modified by Motor City Vette, 1:26 PM 4/2/2002]
Burning Brakes
Joined: Mar 2002
Posts: 803
Likes: 0
From: South San Francisco CA
Re: C3 Backfiring / Idling Low (Motor City Vette)
Sounds like it's running rich. Did you check the needle/seat assembly for dirt? Have you replaced your fuel filters lately? Just some things I've experienced in the past. Also, sometimes a small piece of carb gasket material breaks off and gets stuck in the needle/seat. That will give you the same symptoms you're experiencing.
Safety Car
Joined: Jan 2000
Posts: 4,143
Likes: 0
Re: C3 Backfiring / Idling Low (Motor City Vette)
What type of carb. are you running ?
....could be timing - but was it previously running good before ???
Need more 'history' on the car prior to the problem before diagnosing it. :chevy
....could be timing - but was it previously running good before ???
Need more 'history' on the car prior to the problem before diagnosing it. :chevy
Instructor
Joined: Feb 2002
Posts: 152
Likes: 0
From: margate florida
Re: C3 Backfiring / Idling Low (Motor City Vette)
most of the time you will find timing to be the problem when you have a back fire keep checking then check again if you can't find the problem but i'm sure you are going to find a timing issue jim
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Verdad Gallardo
Instructor
Joined: Jun 2000
Posts: 249
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From: Neustadt/Weinstr, Germany
Re: C3 Backfiring / Idling Low (Motor City Vette)
Might be vacuum related. To check this, plug the vaccum directly at the intake manifold. The headlights and wiper door will not operate, but for a test drive this is no problem.
Thread Starter
Safety Car
Joined: Mar 2002
Posts: 4,366
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From: Las Vegas NV
Re: C3 Backfiring / Idling Low (Mark69)
It's a new Holley carb. I could tell the timing was a little off, but it seems to have gotten worse (maybe it's just my imagination). Anyway, I didn't have the backfiring before and the car has just started to stall at idle. I'm going to have someone give me a hand on Friday to take a look at the timing and the carb. If those check out okay we'll also go over the vacuum settings. I'll keep you posted in case anyone else runs into the same problems.
Melting Slicks
Joined: Mar 2001
Posts: 3,365
Likes: 5
From: Lake Villa IL
Cruise-In IV Veteran
Cruise-In V Veteran
St. Jude Contributor
Re: C3 Backfiring / Idling Low (Motor City Vette)
Is it actually backfiring? Or is it just misfiring? Check the vacuum and see what it is. Also, check your spark plug wires. I know I melted a few on my headers, after long freeway drives, and had similar issues. Another problem source, is the air cleaner interfering with the carburetor linkage.
