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#1
12-16-2017, 10:19 AM
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Vacuum leak ideas
My car when started cold will cut off quickly. I have a A/F meter on it and it runs into the lean, then dies.
However once the engine warms up, it runs fine. Idles fine, etc. So I believe, once the metal warms up and expands, it seals itself. Any chance it is anything other then the intake? I have redone it twice now. warpage is my next thing to check. I have triple checked everything. Propane trick finds nothing. PS, I just had a electric choke installed on the center carb. Looks fine. About a 1/2 inch opening when cold.
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........I'm just learning as I go....... |
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#2
12-16-2017, 12:08 PM
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Its going to take time to get the choke adjusted, Close it off more, and try again. Be sure the cam for the fast idle screw is good so it idles faster when cold. I doubt you have a vacuum leak.
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1968 Firebird 400 RAII M21, 3.31 12 bolt, Mayfair Maize. 1977 Trans Am W72 400, TH350, 3.23 T Top Everyone you will ever meet knows something you don't. Bill Nye. |
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#3
12-16-2017, 12:19 PM
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O2 sensors readings are pretty much usless when engine and exhaust is cold.
Not enough choke. Too lean. Choke spring tension and pull-off is a balancing act. Dead cold, room temp, engine off, the choke flap should just close against the air horn. Then apply vacuum with a hand held vacuum pump and adjust to pull open .250 inch for a starting adjustment. Then depending on rich or lean when started, adjust pull-off accordingly. If it loads up and gas foul the plugs, then increase amount of pull-off. If it starts, revs to fast idle, then dies, less pull-off may be needed.
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Bull Nose Formula-461, 6x-4, Q-jet, HEI, TH400, 8.5 3.08, superslowjunk Last edited by Blued and Painted; 12-16-2017 at 12:34 PM. |
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#4
12-16-2017, 01:12 PM
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I agree with above, maybe just need more fuel until it warms up.
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Tim Corcoran |
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#5
12-16-2017, 06:32 PM
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"O2 sensors readings are pretty much usless when engine and exhaust is cold."
Yep. I love my AFR gauge. But when I was dialing in my choke I relied on it too much. Until someone clued me into the above fact. I forgot about the AFR and made changes to the choke. Got it dialed by and watching, listening, smelling the engine.
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- Tom |
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#6
12-17-2017, 07:52 AM
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For a engine to start well and run good when cold the choke needs to close all the way when you first tap the gas before cranking and once the motor does start the choke pull off and linkage adjustment needs to pull open the choke by no more than 1/8"
If your watching the air to fuel ratio it needs to in the range of 1 part air to 12 to 14 parts fuel.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#7
12-17-2017, 07:19 PM
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