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Hey all; Am helping a freind with a 65 300hp/glide car and 3;36 gears. the car runs good but gas mileage is 10.5/gal.. We found bad points and a closed exhaust crossover vlv. Is it posible that the metering rods and jets are actually worn in the carb. idle screws work great and trans downshift is set right. Thanks in advance; David
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Re: c-2 (65) gas mileage
Carb. is a carter AFB. David -
Re: c-2 (65) gas mileage
David,
I would first start by installing a new heat riser valve or getting the old one to move freely, then pull the spark plugs and note the condition and color of the plugs. If you have a 63 shop manual there is a section on tune up and it describes what a spark plug should look like under normal operating conditions. If the plugs look good your problem may not be in the carburetor and a tune up with points, condenser and spark plug wires may be in order. It's also a good idea to pull the distributor, clean, lube and check the centrifugal and vacuum advance to be sure all is working and free moving, this will not cost anything just some time.
If the carburetor does not leak and the engine doesn't smoke with black rich smoke I would not touch the carburetor until last but I guess anything is possible with regard to metering rods and jets being wore out.Comment
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Re: c-2 (65) gas mileage
I had a 64 years ago that got very poor mileage when I bought it. The problem was the vacuum advance in the distributor. For reference, the car should get around 16 mpg on the highway (14 with ac on). I have put over 100k miles (total) on three midyears, all 300hp auto. Don H.Comment
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Re: c-2 (65) gas mileage
Thank you Tim and Don, I was thinking the mileage should be just what Don said and I will check out the vacuum advance next. the exhaust valve is wired open now with a new one on the way. DavidComment
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Re: c-2 (65) gas mileage
Dave –
My Corvette is a ‘66 300hp/ Powerglide with AC, ex-smog, and 3:36 standard AK ratio. Other than the type of carburetor the cars are similar. Gas mileage was very bad, detonation frequent, and lack of power at low speed.
With the help of this board, Duke W., and Bill C.; I pulled the distributor checked the drive gear dimple orientation to rotor; vacuum can operation 15 deg., rebuilt distributor, and curved the centrifugal advance as close as possible 24 deg. It needed stronger springs. After installing, I made sure the vacuum advance had a full vacuum source at idle not ported, set initial timing at 6 deg. advanced and double checked the timing curve with a dial back timing light for a total of 45 deg. at cruise.
Managed it get 13 mpg around town and 17 on the highway with AC. Power is back, passing gear is great, and it is fun to drive.
Mark #35760Comment
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