Bad Gas Mileage

[Titleist16]

I bought my 62 Comet about 6 months ago and it has been getting bad gas mileage. It has a rebuilt Motorcraft 1bbl on the stock 200. It also has a new 3 row radiator, starter, cellinoid, air filter, breather cap, and the Pertronix is on the way as we speak. I have read on here that you guys are getting anywhere from 15-25 mpg, I get about 9 mpg. I noticed that when I drive it I do notice the smell of gas sometimes and was wondering if maybe there's a gas leak somewhere.
Is there anything else I should check for to try and get this thing from using so much gas? How do I go about checking the gas lines for leaks?
Thanks

 

[Anonymous]

u check the gas lines for leaks by holding a lighter along the pipe/hose, lol...just KIDDING...DONT DO THAT....but just turn the car on for awhile, if u are leaking gas there will be a wet spot. Did u rebuild the carb? or did u buy it rebuild...it runs smooth? 9MPG in a comet is really BAD...i got that in a big 4 door oat and the jet was twice the size...so theres probably more to it than the carb...check timing i guess....whatever...i dont really know, but its alwasy fun to play around with stuff under the hood, and if u screw something up its just a good reason to upgrade

 

[CZLN6]

Howdy back:

Start checking at the back of the car, where the fuel goes into the tank. This piece of hose, between the gas filler neck and the tank, is frequently old, cracked, rotted and leaking.

Since gas evaporates quickly, do your check slowly. Watching, smelling and feeling for wet spots or areas. Gas will also run along lines looking for the low spot before dripping. Work your way forward giving special attention to connections- especially rubber hose joints.

Check the line connection into the carb carefully. Once all leaks have been found and fixed, check the carb. Make sure the Automatic choke is opening properly and that the needle valve in the float is not sticking open and sealing when closed. Set the choke as lean as possible.

Make sure your air cleaner is open/not blocked, and working efficiently.

Make sure your initial timing is set correctly, with an additional 5 degrees over what stock calls for. Make sure your whole ignition system is working as designed. Make sure your vacuum advance cannister is working properly along with the mechanism inside the distributor. Make sure your coil, plugs and plug wires are in tip-top shape.

Make sure you don't have a plugged or kinked exhaust pipe. Make sure your thermostat is giving you a quick warm up.

Finally, air up your tires, make sure your brakes aren't draggin', eliminate anything you don't need to carry around- lightening the load, slow down and drive as if you had a raw egg between your right foot and the gas pedal. Coast more- idle less-drive smarter and enjoy the savings.

Tuning for economy:
Hotter is better.
Leaner is better.
lighter is better.

Adios, David

 

[Anonymous]

only egg I ever remember in driving was that one brady bunch episode where greg challenged marsha to a driving contest

but I digress

 

[mugsy]

T-16,

Besides the other suggestions listed above (which are all good) also perform a compression test. My '65 Mustang 200 had compression in the 135-150 range and got only 13 mpg. I finally tore into the motor and found/verified the rings were pretty much shot. A compression test will tell you the general condition of the engine, which is related to the mpg.

Mugsy

 

[Titleist16]

While I was tracing the fuel line for leaks I discovered that the fuel pump is leaking where the top half and bottom half screw together. Hopefully this is the problem that's killing my gas mileage. Thanks for all of the suggestions.

 

[Titleist16]

Well I just replaced the fuel pump, the rubber hoses, fuel filter, adjusted my carb to idle lower, put Pertronix in a few weeks ago, I put some engine cleaner in my gas about 2 months ago and it doesn't seem to help much. I was wondering, there's a screw at the front of my carb that's looks like you turn it with a flathead screwdriver and it says lean on one side. Is this what I turn to make the fuel mixture leaner? And where the tailpipe bolts on to the exhaust manifold it keeps coming loose. I've taken to the shop like 3 times and evertime they fix it, it will run great for about a week and then it will come loose again. Anybody have this problem? Thanks

 

[LEROY POLL]

HI T-16


..... TRY THIS FOR A FIX. THERE IS A BRACKET THAT BOLT TO THE MOTOR BLOCK ON YOUR MOTOR. IT IS JUST IN FRONT OF THE STARTER. THAT BRACKET SHOULD HAVE A U-BOLT AROUND IT AND BOLTED TO THE TAIL PIPE. IF IT IS MISSING YOU WILL NOT BE ABLE TO KEEP THE TAIL PIPE ON. SEE IF IT IS MISSING.

.....THE NEXT THING WOULD BE TO GO TO A LATER EXH. MANIFOLD. THE 1966 AND UP MANIFOLDS HAVE A DONUT FITTING TO KEEP THE TIGHT FITTING YOU NEED. THIS WILL ALSO GIVE ABOUT A 3 OR 4 HP. INCREASE.

.....IF THAT WON'T HOLD IT DOWN THEN HAVE YOUR MUFFLER MAN WELD THE BRACKET TO THE PIPE. THAT WILL HOLD THE PIPE IN PLACE EVEN IF ALL THE BOLTS COME OFF. THE PIPE WILL COME OFF ONLY WHEN YOU UNBOLT IT FROM THE SIDE MOTOR BRACKET!!! THIS WILL WORK ON ANY OF OUR MOTORS.

LIVE IN GRACE

LEROY POLL

 

[Anonymous]

As mentioned previously, don't overlook the timing and the vacuum advance cannister. You can test it for leaks by disconnecting the line from the carb and using a vacuum pump and guage or just suck on it. It should hold a vacuum and not leak off. Also pop the cap of the distributor when you do this to see if the mechanism in the distributor moves when vacuum is applied. If you have a timing light, revving the engine should advance the timing mark sharply. If your distributor is original, the vacuum advance controls all spark advance. If the vacuum advance is not working then mileage will suffer.

 

[Titleist16]

Where is the vacuum advance canister? I just put the Pertronix unit in so do I still have to take the dizzy cap off?

 

[Anonymous]

It should be attached to the distributor housing. It should have a piece of tubing that runs from a fitting on the distributor to the carburetor or below it. It looks like a vacuum motor. Inside it contains a diaphram that has a rod attached to it on the distributor side. As you suck on the fitting, the diaphram will pull the rod inside the distributor. The rod is attached to the plate in the distributor and rotates it as vacuum changes.

 

[Titleist16]

I checked the vacuum advance thing in the distributor and it moves a little when I suck on the line so it appears that that's working. While I was tracing lines from the carb I noticed that one of the lines is capped off. It is the line that is on the top left of the front of the carb where the screw that says Lean on it is. The carb says Autolite so I presume that it's an Autolite 1100 with a manual choke. My question is should this line be capped off? If not, what does it go to? i found a picture of it at
http://www.albertpenello.com/mustang/engine.html


Thanks[/url]

 

[Anonymous]

I had a 61 Comet with a 170. It got bad mileage when I bought it, around 15 mpg. I tuned it up and replaced the vacuum canister on the distributor and boosted it up to over 20 mpg. I seem to remember getting about 26 on the road. Make sure the advance holds vacuum and also that it is hooked to the correct vacuum port on the carb. If it is hooked to straight vacuum, it will work backward. Pull the line loose at the dist. At idle, there should be no vacuum on the line. Speed up engine and the faster, the more vacuum should be felt.

 

[Anonymous]

Did the 62 Comets come with the 200ci? I thought 170 was the "big" one.

 

[Titleist16]

170 was the biggest engine for the 62 but mine isn't the original, it's a 69 200.

 

[Anonymous]

Yeah, my 62 is a 68 block with a 69 head (with the 1.75 valves).

 

[Titleist16]

Fairmont 200,

I checked the vacuum line going to the vacuum canister and it does have vacuum at idle and it gets stronger as I rev higher. To my ear my car sounds like it might idle a little high but my shop teacher said its at 650 when we tested it. What should I do about that? Also, There is another vacuum line on my carb that is capped off and doesn't go anywhere, should this be hooked up to something? Should there be extra vacuum lines? About how much would a vacuum canister cost?

 

[Anonymous]

Vacuum canisters are fairly inexpensive. I think I paid about $7.00 for one a couple years ago. Yours might be fine. If it is old and the outside oily and dirty, there is a good chance the diaphragm inside is leaking. You need to hook a Mighty-Vac (hand held vacuum pump) to it and see if it will hold vacuum. As far as the extra fitting on the carb, if it is not the original, it is hard to say where it might go. You probably don't need it for your Comet. The line going to the advance should not have any vacuum on it at idle, or very, very little. If you can feel vac @ idle, something is wrong, I don't think you have the correct line hooked up. If you have a vacuum gauge, hook it to this line and see what is happening. At cruising rpm (around 2500)I would think you should have about 12-15 inches in this line. I have never checked one like yours, but this should be close. The vacuum should increase with rpm. If the vac is more when you let off the throttle, this is wrong, and needs to be corrected before you will get decent mileage.