I was hoping it was the Winter blend of gas which I had purchased in November last year 2024 , and has more Butane in it than the Summer blend of gas dose and the extra added butane causing it to want to stall once it's warmed up , but today I purchased some fresh Sunoco 93 octane which I always use , and I always add 1 ounce of Stabile for each 2-1/2 gal. of gas . Once the engine is warmed up it will stall out at idle . I have checked the timing , and it always has idled around 900 rpm . The 289 Hi-Po engine in the car was just freshly re-built , and the odometer had 89, 990 miles when I purchased the car back in March 2005 and it now has 93, 603 . It has a correct 65 HI-PO carb from pony carbs . It always ran great for 19 years . Now it runs great until it's warmed up ? I have changed the fuel filter on Fred's button top pump once , but have not ever changed the screw in one in front of the carb . To me , because of the fact it runs so good for 30 to 45 min before it starts to act up tells me that it's not a fuel filter issue , but some sort of vapor lock ? Now I'm starting to think that it could also be the 20 year old Pertronix II , or possibly the 20 year old brown reproduction coil , and not fuel related because when it quits it dose not sputter out , but just shuts off , and when you let it cool down it runs again . Any help would be greatly appreciated .
65 HI-Po wants to stall after it's warmed up ?
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Perhaps it's time for a rebuild of the carb? 2025-2009=16 years and you've only driven it about 3,500 miles in those 16 years. I would suspect with the fuel evaporating over and over in that length of time it would leave some deposits in the bowls and the passages (maybe a restricted idle circuit) even though you've been using Sta-Bil.
Hopefully some of the more knowledgeable people on this site will chime in with additional things you can check.
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I was hoping it was the Winter blend of gas which I had purchased in November last year 2024 , and has more Butane in it than the Summer blend of gas dose and the extra added butane causing it to want to stall once it's warmed up , but today I purchased some fresh Sunoco 93 octane which I always use , and I always add 1 ounce of Stabile for each 2-1/2 gal. of gas . Once the engine is warmed up it will stall out at idle . I have checked the timing , and it always has idled around 900 rpm . The 289 Hi-Po engine in the car was just freshly re-built , and the odometer had 89, 990 miles when I purchased the car back in March 2005 and it now has 93, 603 . It has a correct 65 HI-PO carb from pony carbs . It always ran great for 19 years . Now it runs great until it's warmed up ? I have changed the fuel filter on Fred's button top pump once , but have not ever changed the screw in one in front of the carb . To me , because of the fact it runs so good for 30 to 45 min before it starts to act up tells me that it's not a fuel filter issue , but some sort of vapor lock ? Now I'm starting to think that it could also be the 20 year old Pertronix II , or possibly the 20 year old brown reproduction coil , and not fuel related because when it quits it dose not sputter out , but just shuts off , and when you let it cool down it runs again . Any help would be greatly appreciated .
If you have a 1965 model with the fuel filter on the pump, you should not have a filter at the carburetor. The 1965 fuel line runs behind the distributor where the 1966 fuel line runs in front of the distributor. Being as the 1966 model has the filter at the carburetor, the fuel line in front of the distribuotor facilitates the changing of the filter.
If your Kar is stalling at idle, I would be looking for a bad power valve in the carburetor as they fail quite often. You should change the accelerator pump diaphragm at the same time as their failure rate is also high and when they fail, you will have a potential fire. The one thing that goes wrong in the 4100 carburetor, and many others, is that the vent holes in the booster become plugged with dirt causing the carburetor float bowls to empty into the cylinders even with the engine off. They are easy to clean with wire from a parts ID tag.
-Fred-
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I would vote for the Pertronix or coil. The Pertronix could easily be converted back to points and the coil replaced with an original. If one or the other fixes the problem, you are done. Sounds like it is a heat related problem. When it gets hot enough, the ignition quits. When it cools down, it works. (When it quits, you can check for fuel in the fuel bowl and/or if you have spark using a timing light.)
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