| Johns46coupe | -- 07-07-2010 @ 10:48 AM |
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I'm having a problem with gas mileage on my 46. I'm getting about 9.8 mpg in mixed city and highway driving. It has a stock Chandler-Groves carb and stock fuel pump. The carb was rebuilt by one of the local old time re-builders. It has #50 jets. He adjusted the float and checked the float valve and accelerator pump. I adjusted the fuel idle screws and the vacuum measured 21-22. Compression is 105 to 120. Distributor has new points and condenser. Car starts easy, runs really well and does not smoke but the plugs are pretty black. What should I be checking?? Thanks John
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| ford38v8 | -- 07-07-2010 @ 11:58 AM |
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John, your mileage isn't too far off, but your plugs should be tan in color. You may have a restriction in your air filter if you've modified it? You may also advance your distributor a bit, and check the vacuum brake for proper operation. Your jets are correct, but you could try 49's, but if that produces a delay when you goose it in traffic, then go back to 50's. Your carburetor choice is unusual in that it is only correct for a '38. Those early carbs do not have an internal vent like the 59's have. This may not measurably affect your mileage, but will tend to dirty up your manifold with overflow. The Chandler Groves are otherwise the same as the 59's but do command a higher price to those who need one for the Concourse. Alan
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| Johns46coupe | -- 07-07-2010 @ 12:20 PM |
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Thanks Alan. The carb was on the car when I acquired it. I assumed it was correct along with Holley and Ford carbs. The air cleaner is stock oil bath unmodified. The distributor has a new vacuum brake cylinder. How is the vacuum brake adjusted? Thanks John
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| 37RAGTOPMAN | -- 07-07-2010 @ 12:32 PM |
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what rear end ratio are you using.?,and do you have dual exhausts? recheck your jets do not go by the number on them,. check with a gauge,because could have been drilled [ reemed out] just be besure. compare them to some others, check for clogged air cleaner,check you milage with out, or use a different one,and clean and check the gap, maybe even change to a different brand might help, hope this helps 37 RAGTOPMAN KEEP ON TRUCKIN,,,, This message was edited by 37RAGTOPMAN on 7-7-10 @ 12:36 PM
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| supereal | -- 07-07-2010 @ 1:15 PM |
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There is a slider on the side of the distributor. Loosen the locking screw and move it up as far as it will go. Loosen the lock nut on the vacuum brake on the distributor, and back off the screw. Run the car and listen for any spark knock. If you hear any, which is unlkely, run the brake screw down a few turns and retighten the lock nut. Because today's fuel is higher octane than the original type, your car will likely run on it without a problem at full advance. We set up distrbutors on our Sun machine to check the action of the advance and to set the brake. It is possible the weight springs are weak or broken in your distributor, if your mileage is so low. My '47, a heavy convertible, gets 12-14 mpg overall. Be sure none of your brakes are dragging, and that the parking brake is fully releasing. Your tires should be inflated to about 30-32 lbs, and the toe-in checked to see if it is correct, about 0 to 1/16". Your engine temperature should be above 160 degrees, about half way up the gauge when warmed up. Carb jet size usually doesn't change mileage much, but a leaky power valve will.
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| TomO | -- 07-08-2010 @ 7:33 AM |
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John, You said that your plugs are black, I would change the plugs and take the car for a drive of about 20-30 miles. Then pull into your garage and shut off the engine without letting it idle. Let the engine cool and then check your plugs for color and wet gas. If they are black or wet with gas, you may have a leaking power valve gasket. If I were you, I would look for a model 59 carburetor that has been rebuilt by a reliable re-builder. Tom
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| ford38v8 | -- 07-08-2010 @ 9:25 AM |
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John, all good advice above. The adjustment of your vacuum brake is described by Supereal, who also makes a good point regarding tires and brakes. If, as you say, the vacuum brake is new, it may not be broken in yet. You can check it by pulling it out and observing the rub zone on the leather. If it has a slight glaze, it should be ok. Again, for the record, your Chandler Groves is more valuable than a 59 to those who need one. The one with no model number is for a '38, and the one with a 91-99 is for a '39. No Chandler Groves were used in '40, only the Ford & Holley from that point forward. Alan
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| Johns46coupe | -- 07-28-2010 @ 10:58 PM |
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Thought I would send an update. The car is still running well but mileage remains poor. Plugs still sooty. Jets are correct and are brand new (saw them installed). Went all over the brakes and park brake. There is no dragging, all release fully with no sounds when wheel is spun. Advanced distributor fully per super and attempted to adjust vacuum brake. No change whether out or in a few turns. Leaving it at a few turns in. The car has dual exhausts, stock unmodified air cleaner. Rear end ratio is 3.54. Think I will take Tom and Alan's advice and put in a Holley 59 carburetor, change plugs and try again. Of course, while I was doing all of this over the last couple of weeks, I adjusted my clutch freeplay and found that I need a new clutch. So, I will replace disc, plate, bearings and bushings and whatever else is needed. Thanks everyone who responded so far. Love this forum. John
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| Texas40 | -- 07-29-2010 @ 6:49 AM |
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An off the wall suggestion. Are you sure your speedo is registering correct mileage? Most 46 in our part of the country have 3:54 gears but your speedo sending unit may be for a 3:78 or 4:11 resulting in false miles driven reading. Check the numbers on the speedo drive gear housing to be sure its compatible with the 3:54. A friend of mine experienced this, when he got his speedo right his mileage concern went away.
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| oldford2 | -- 07-29-2010 @ 10:08 AM |
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John, I have a 46 with the original 59 carb (rebuilt) .048 main jets, 3.78 rearend. We just took a 1500 mile trip in it to Nova Scotia and checked the mileage closely while in the states where we have gallons (liters in Canada). We got 18+ going 55 to 60 in 85 - 90 degree heat. The speedometer is 8-10 percent over so I figure almost 17 mpg. We burned/leaked 1 1/2 qts of oil. I also have a top oiler installed (MMO) so that can soot up the plugs a bit. With your 3.54 you should do better. I think your power valve may be leaking or faulty. You can check your speedometer with a GPS (Most will run on their battery for 2 or 3 hours.) John This message was edited by oldford2 on 7-29-10 @ 2:20 PM
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| keith oh | -- 07-31-2010 @ 8:05 AM |
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This very simple thing, the air cleaner-silencer must be kept clean and free of any obstructions, otherwise it acts like you are running with the choke partially engaged.
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