Any helpful suggestions
Thread Starter
Racer
Joined: May 2005
Posts: 306
Likes: 0
From: Annandale Va
Any helpful suggestions
Just installed new Hooker Headers and sidepipes. I start the car up and starts fine. Warms up idels about 750 to 800rpms. Drive it for a short time, couple of miles up to store runs great. Leave head back home about halfway home notice it's ideling about 1500 to 2000. Rev it a couple of time to see if it will drop back but no luck. Then when I pull into drive and shut it off a half second later pretty good backfires out of pipes.
Engine is 350 with Edelbrock manifold and Carburator.
Any suggestion of where to start tweaking to rid this.
Thanks in advance for any help.
Engine is 350 with Edelbrock manifold and Carburator.
Any suggestion of where to start tweaking to rid this.
Thanks in advance for any help.
Racer
Joined: Dec 2001
Posts: 328
Likes: 0
From: Dallas County Texas
Maybe you knocked loose a vac line?
Did you possibly hit the carb at all? Throttle shaft bend or a damaged carb gasket could be a problem - something that's causing the effect of a vac leak once warm......
That is a pretty weird one....it should breathe easier with the new exhaust....but the idle speed increase on warm up and a rich condition....hmmmmm.....
That is a pretty weird one....it should breathe easier with the new exhaust....but the idle speed increase on warm up and a rich condition....hmmmmm.....
Drifting
Joined: Nov 2001
Posts: 1,469
Likes: 6
From: 68 427 4.11s Roadster
Instead of shutting engine off check to see if the throttle is touching the idle screw, if it ain't find out why.
As mentioned fast idle from choke? Springs (should have 2) aren't returning it? binding? Misadjusted throttle cable, which I doubt.
As mentioned fast idle from choke? Springs (should have 2) aren't returning it? binding? Misadjusted throttle cable, which I doubt.
Thread Starter
Racer
Joined: May 2005
Posts: 306
Likes: 0
From: Annandale Va
thanks for the help
Thanks for you help in starting to solve problem. Nothing on the carb was hit or moved almost all of the work on the headers were from the bottom and don't think that is the problem at all.
The number eight pipe on header appears to get hotter than the rest, is this a symptom of anything.
Unforturnately I know just enough about timing and carbs to be dangerous. One of the other items it has a slight muffled pop as you cruise along at a constant speed and when you come to a stop but when you come to a stop and turn it off you get a short delay and then pow a pretty good back fire out of both sides.
Probably start tomorrow from begining with timing and see if that might be problem.
again thanks for the helpful suggetions.
The number eight pipe on header appears to get hotter than the rest, is this a symptom of anything.
Unforturnately I know just enough about timing and carbs to be dangerous. One of the other items it has a slight muffled pop as you cruise along at a constant speed and when you come to a stop but when you come to a stop and turn it off you get a short delay and then pow a pretty good back fire out of both sides.
Probably start tomorrow from begining with timing and see if that might be problem.
again thanks for the helpful suggetions.
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Team Owner
Joined: Jul 2004
Posts: 40,380
Likes: 788
From: Redondo Beach, California
The extra hot header pipe and the higher idle rpm are consistent with a lean mixture.
When you installed the headers, did you use a cylinder head/header gaskets that blocked off the carburetor heat passage? On the stock engine there was a little port that allowed exhaust gasses to flow from one side of the engine to the other. This heated the carb and also provided heat for the automatic choke. If this passaage is blocked with new gaskets, the automatic choke may not be working and you may have inadvertently done something to force the engine to run correctly at idle, but with no choke action, the engine doesn't run correctly when hot....
...Im just trying to help. Maybe you know all this stuff about interactions about the exhaust gas intake maniford passage and the choke thermostat. Anyhow, if one exhaust pipe is running hot, that's still a problem.
When you installed the headers, did you use a cylinder head/header gaskets that blocked off the carburetor heat passage? On the stock engine there was a little port that allowed exhaust gasses to flow from one side of the engine to the other. This heated the carb and also provided heat for the automatic choke. If this passaage is blocked with new gaskets, the automatic choke may not be working and you may have inadvertently done something to force the engine to run correctly at idle, but with no choke action, the engine doesn't run correctly when hot....
...Im just trying to help. Maybe you know all this stuff about interactions about the exhaust gas intake maniford passage and the choke thermostat. Anyhow, if one exhaust pipe is running hot, that's still a problem.
Team Owner
Joined: Jul 1999
Posts: 26,545
Likes: 46
From: Huntersville NC
Originally Posted by 68/70Vette
The extra hot header pipe and the higher idle rpm are consistent with a lean mixture.
headers improve the flow of gas through your engine: obviously exhaust, but also air on the intake side. I believe you are supposed to richen your carb when you install headers. (not just the idle, but your primary jets) That may cause you to be running lean.