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Discussion Starter #1
Just curious what others have done to cure the low gas mileage issues. I have a 302 with Holley 4b (600cfm) and average about 10-11 mpg. This was a 1 owner car kept in great condition, except he didnt drive it much the past 10 years (only 400 miles total). Most of the hoses were older, so I just finished replacing the carb hoses, headlight vacuum hoses, and radiator hoses. My RPM's tend to run around 28K at 65 mph and 30K at 70mph. Yes, I know that is a little fast, but in California you will be run off the road going any slower than this. Anyway, any advice is greatly appreciated.

P.S. This is my first of many posts. Thanks for having this site.
 

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28,000 - 30,000 rpms ? Boy thats one steep set of gears. Pretty good milage for those rpms. Must be one hell of a well built 302...JK...Couldn't resist....Make sure your choke is kicking off once the engine is warm, Check timing,Upgrade to electronic ignition, Check air in tires, rebuild carb.
 

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Thanks for the reply. I thought the gears were high also, so i lifted the rear end and manually rotated both tires together. It's the standard 3.0 rear end the car came with. Choke kicks off after about 2 min and a few pushes on the pedal. rsting idol is 8-9. The carb is new (relatively). I believe it was purchased about 10 yrs ago with only 1,000 miles on it. I will recheck the timing, since I havent dont that yet.
 

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Discussion Starter #4
What is Dyno testing? Would this help me determine if my engine is slowly dying? It's the origanal with about 140k miles on it.
 

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Most Holley carbs come jetted a bit too rich for a 289 or 302. You need to decrease the jet size until you start to get lean surge under part throttle cruise conditions. Then go two sizes bigger and it will be about optimized.

Update your profile to include your location and add the details about your car in the signature. This will help people make better recommendations for your situation.
 

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Your motor will perform better, give better gas mileage if you advance the timing above the recommended specifications.
Advance the timing until the motor starts to ping in a hard pull, then back off (retard) the timing until the pinging stops.
 

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Check your plugs, wires, points. Weak ignition will kill your gas mileage. Just as reference, my '69 with the a/c on at 70 - 75 mph, 2800 rpm, will give me about 17mpg with 2.75 gears. Can't use my '68 as a reference since it's not stock.
 

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Discussion Starter #8
Thanks, I will check the timing, plugs, and wires this weekend. 17mpg is better than 10 especially with 4 dollers per gallon coming up. Also, I have a feeling the carb is running rich since there's always a moderate gas smell after driving around town. I do have to say the gas smell greatly reduced after replacing all the vacuum hoses.
 
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