Still chasing a high idle
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
Still chasing a high idle
I could write a really long post on this but I'll keep it to one question. Can a high idle (1100-1200 rpm) be caused by a vacuum leak if the air fuel ratio is slightly rich in the high 13s? And assume that the carb is not the problem, it has been checked out by the local Forum carb expert and everything was running fine with it mounted on his test engine.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Yes it can.....there are several reasons why...and several versions of the high idle problem.
Start from scratch......if the intake is sealed proper, carb base is sealed proper, and no vacuum leaks along the runners in the form of a crack or a fitting, then shutting the throttle blades all of the way will stall the engine. Period. Do not try to over think this.....forget about your mixture, the election, price of beer......you ARE sucking air in from somewhere......period. Find the leak, solve the problem.
Jebby
Start from scratch......if the intake is sealed proper, carb base is sealed proper, and no vacuum leaks along the runners in the form of a crack or a fitting, then shutting the throttle blades all of the way will stall the engine. Period. Do not try to over think this.....forget about your mixture, the election, price of beer......you ARE sucking air in from somewhere......period. Find the leak, solve the problem.
Jebby
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
Yes it can.....there are several reasons why...and several versions of the high idle problem.
Start from scratch......if the intake is sealed proper, carb base is sealed proper, and no vacuum leaks along the runners in the form of a crack or a fitting, then shutting the throttle blades all of the way will stall the engine. Period. Do not try to over think this.....forget about your mixture, the election, price of beer......you ARE sucking air in from somewhere......period. Find the leak, solve the problem.
Jebby
Start from scratch......if the intake is sealed proper, carb base is sealed proper, and no vacuum leaks along the runners in the form of a crack or a fitting, then shutting the throttle blades all of the way will stall the engine. Period. Do not try to over think this.....forget about your mixture, the election, price of beer......you ARE sucking air in from somewhere......period. Find the leak, solve the problem.
Jebby
Price of beer, lol all the ones I like are about 10 bucks a six pack
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Now start it up and see if it changes. If it does....then reconnect each vacuum line one at a time until the high idle comes back and that’s the culprit.
I drink Heineken Light on payday and Bud Light the rest of the time Lol!
Jebby
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
The thing to do is disconnect and put vacuum caps over every vacuum port on your manifold and carb.
Now start it up and see if it changes. If it does....then reconnect each vacuum line one at a time until the high idle comes back and that’s the culprit.
I drink Heineken Light on payday and Bud Light the rest of the time Lol!
Jebby
Now start it up and see if it changes. If it does....then reconnect each vacuum line one at a time until the high idle comes back and that’s the culprit.
I drink Heineken Light on payday and Bud Light the rest of the time Lol!
Jebby
Thread Starter
Pro
Joined: Oct 2011
Posts: 554
Likes: 82
From: San Jose CA
Oh yeah did that. Found a bit of a leak at the power brake connection using that method, that's tight now but otherwise, nothing. I was able to do some smoke testing today. Connecting to the Y port at the back of the manifold and at the air cleaner snorkel flap, in both cases a good amount of smoke came up through the primaries. I also may have seen a very slight wisp from the china wall near the distributor. The Y that I am using has only two outlets, one to the cruise control that is blocked off and the other to the headlight doors. Thoughts?
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