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Discussion Topic:
1948 6cyl H carb.
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edscoupe |
06-08-2013 @ 7:16 AM
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Member
Posts: 9
Joined: Dec 2010
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What size jet should I be using in carb. in Mn metro area. Getting only 12 miles per gallon with 64 jet. Thanks Ed
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ken ct. |
06-10-2013 @ 8:57 AM
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Senior
Posts: 1513
Joined: Jan 2010
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Accually that is the correct # for "H" engine. ken ct possibly something is wrong in the carb.OMO. Ive rebuilt dozens of these and there a good running carb.
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supereal |
06-10-2013 @ 9:46 AM
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Senior
Posts: 6819
Joined: Oct 2009
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The jet for 5000 ft altitude and below is .065, for 5000-10000 ft, .063. A more likely suspect is the economizer valve. It is a spring loaded piston normally held at the top of its stroke by manifold vacuum. When the manifold vacuum decreases to 8-9 in hg, the spring forces the piston down to open the valve. This increases fuel flow without passing thru the metering jet. The piston could be stuck or sticking, or the manifold vacuum may be low. Either could account for high fuel consumption.
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edscoupe |
06-10-2013 @ 6:33 PM
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Member
Posts: 9
Joined: Dec 2010
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Thanks I will replace the economizer valve and see if it helps
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supereal |
06-10-2013 @ 7:12 PM
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Senior
Posts: 6819
Joined: Oct 2009
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Also check your manifold vacuum.
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TomO |
06-11-2013 @ 7:07 AM
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Senior
Posts: 7250
Joined: Oct 2009
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Ed, check your spark plugs before you make any changes. If they are black and sooty, you are running rich and have carburetor problems. If they are a tan color, your mixture is correct and the poor mileage is due to other considerations. Make the test after driving for more than 30 minutes at highway speeds with little or no idling.
Tom
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edscoupe |
06-11-2013 @ 1:27 PM
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Member
Posts: 9
Joined: Dec 2010
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spark plugs are light tan, I am looking for a vacuum gage. Might be distributer, timing is set a 0 by the book. Starts and runs great, I think mileage should be a little better, I may be hoping for to much, was getting around 16 per gallon a year or so ago.
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supereal |
06-11-2013 @ 2:01 PM
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Senior
Posts: 6819
Joined: Oct 2009
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That much drop can be due to low tire inflation, one or more dragging brakes, poor alignment,or too much alcohol in the gas. Have your distributor checked on a machine to verify the advance. I uually get between 12 and 14 mpg with my '47, depending on how much city driving is done. I once had a '46 six cylinder sedan coupe that rarely got more than 12 mpg.
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edscoupe |
06-12-2013 @ 7:12 AM
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Member
Posts: 9
Joined: Dec 2010
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This is the 6cyl H motor, check vacuum today and at 500 rpm it was at 17, according to manual for gage it should be between 18-22. Reset timing so that I have 22 on gage at 500 rpm. I will run a couple tanks of gas through it and see if there is any change. I changed tire size about a year ago from 600-16 to 670-15 tubeless with new rims with safety bead 32lbs air. This new gas could also be at fault. Thanks for your help Ed
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4t6v8 |
06-15-2013 @ 3:31 AM
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Member
Posts: 5
Joined: Oct 2009
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When you changed tyre sizes, I would expect the speedo/odometer readings to differ, unless the speedo gear was changed accordingly. I suggest you check the mile recorded on your odometer is a mile on the road, if not, this would effect your calculations. You mention a year ago you got 16mpg and a year ago you changed your tyre sizes. Worth considering I think.
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