64 cold start-fast idle inconsistancy
My 64 300HP (powerglide with factory air) with original AFB completely rebuilt carb (by NCRS carb) specialist, has new choke assembly, new heat riser valve... on first start in the morning with one good throttle pump (and the air conditioning off) the engine starts inconsistently...some mornings on the first start it goes up to the fast idle rpm's of at least 1000 or more...but hardly ever to what the PV manual says it should be of 1500-1800 rpm's. Then the next morning it sputters and goes immediately to low idle or dies...tried everything in the adjustments, read the 63 shop manual, and 64 supplement...something is just not working right. Suggestions?
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Re: 64 cold start-fast idle inconsistancy
John,
Well, if it is not cold enough the choke will not set all the way to get that fast of an idle. Be sure that the bimetallic spring in the choke is good.
It is important to press the pedal slowly to allow linkage to set choke initially.
I'm sure you have already insured all linkage is free and no binding. Heat tube passage ways are clear, no corrosion/breaks thru heat tubes.
Older bimetallic springs lose ability to meet spec as the book presents. -
Re: 64 cold start-fast idle inconsistancy
I'm not certain who your NCRS carb specialist was, but with all the problems I had to fix with one done by an "expert" from the northeast, I have little faith to assume that will make it alright. It may look correct from the outside, but have mix/match parts inside. If you want to know the sad details, send me a PM and I'll respond.
Stuart Fox (28060)Comment
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Re: 64 cold start-fast idle inconsistency
It's a combination of the choke, idle setting and mixture.
Do you have the Shop Guide? if not, it would help.
The choke should operate easily and not bind. You need to remove the choke to check that. It has a tendency to get dirty on the inside and should be cleaned. There should be an o-ring between the choke and the carb vacuum when you reinstall the choke. The o-ring fixes lots of problems.
The dial indicator should be set at the mid-point to start.
The shop manual will help with idle and mixture, too much to type in here.
Good luck.
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Re: 64 cold start-fast idle inconsistancy
John,
Start by double checking the choke coil bakelite cover adjustment so it's set to the index mark (center).
Next, manually close the choke completely (hold it closed and open/close the throttle so the fast idle cam drops) and look on the drivers side to see if the fast idle screw sets to the scribe mark on the fast idle cam. That's the high step on the carter afb and with a FULL tight closed choke it should set at the mark. There is a picture of this in the 63 shop manual and the adjustment is to bend the rod if necessary so with a tight choke the screw and mark line up.
Third, Start the car and allow the engine to completely warm up and when good and hot manually set the fast idle cam on the high step so the high idle scribe mark lines with the screw and adjust the fast idle screw to obtain 1750 rpm with a hot engine.
The choke should work fine after this, I suspect your problem is that the fast idle screw is not set high enough and on the lower steps of the fast idle cam it's at curb idle because the screw is not touching the fast idle cam. That's a adjustment that needs to be done on the car with a warm engine and can only be ballparked on the bench when overhauling.
The correct way to check the choke coil tension is at approx 68* the choke should close completely but not slam tight like in cold weather. If you start the car say at 75* the choke may not set on the high step but that's a function of the choke coil setting and for automatic engine the index setting is used, (center mark on housing). My experence is that with the adjustments set correctly the choke coil is usually fine.
The only other adjustment is the vacuum break and your rebuilder should have set that on the bench. You can check it using a paper clip and it's easy to set but read the book so you understand this adjustment. If you decide to check it don't drop the drill down the throat of the carburetor..
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