170ci 170 2AT 62 Comet - 10MPG?

[dydaktix]

My mpg seems to be way low. Just got the car; everything is stock and all original. What steps would y'all take to troubleshooting?

 

[bmbm40]

Gas leaking somewhere?

 

[bubba22349]

These are the way's and in the general order that I check for these type of problems.

First Check for any vacuum leaks especially at each of the two Carb"s Base mounting gaskets and at the Carb's Throttle Shaft on the linkage side, these are some of the most common places to find vacuum leaks also check for leaks at others vacuum lines you might have such as for the PCV and the vacuum line going to the Transmission Modulator etc.

Next Check the SCV is working plus the LOM (Load O Matic) Distributor's Vacuum Advance Canister will hold a vacuum.

Finally if all the above items check out or if any problems that were found are fixed check that all of your 170's Tune up settings are correct

These are the important Tune Up Specs for a 1962 Ford Falcon or Comet with a 170 Six and an Auto Trans. The Firing Order is 153624

1. The stock spark plug used was a Motorcraft BF-82 set the Plug Gap .034
2. The Distributors Points can be set to a basic .025 but for best results for economy they need to be set to 37 Degrees of Dwell
3. The Base Ignition Timing is set to 10 Degrees BTDC for the Auto Trans Cars.
4. The 1960 to 1962 early Six Engines all had a Solid Lifter Cam so with the engine warmed up good set the Intake & Exhaust Valve Lash to .016 Hot
5. With the engine warmed up good do a Compression Test to determine the engines over all condition.
6. With the engine warmed up good set the Carb's Mixture Screw to the Lean Best Idle.
7. With the engine warmed up good set the Carb's Curb Idle to 500 RPM with the Trans in Drive and the parking Brake set and wheels blocked or with someone else stepping on the brakes.

With an engine that's in very good condition after its tune up is right it should give you excellent Fuel Economy of double or more MPG than what your now getting, best of luck.

 

[B RON CO]

Hi, let's assume the car is in a good state of tune and the brakes are not dragging. The best way to determine the miles per gallon is to fill the gas tank until the nozzle clicks off. Write the mileage down. Drive until the gas is down to 1/4 tank. Fill the tank and write down how many gallons it took. Subtract previous miles from current miles, this number is the miles you drove. Divide the miles you drove by the gallons used. Lets say you drove 175 miles, and used 11 1/2 gallons of gas. 175 divided by 11.5 is 15.2 is miles per gallon. Good luck

 

[R_Calris]

Hi, let's assume the car is in a good state of tune and the brakes are not dragging. The best way to determine the miles per gallon is to fill the gas tank until the nozzle clicks off. Write the mileage down. Drive until the gas is down to 1/4 tank. Fill the tank and write down how many gallons it took. Subtract previous miles from current miles, this number is the miles you drove. Divide the miles you drove by the gallons used. Lets say you drove 175 miles, and used 11 1/2 gallons of gas. 175 divided by 11.5 is 15.2 is miles per gallon. Good luck

I would do this three times (if possible) to get a decent average as humidity, temp, wind, and other weather conditions can effect the numbers.... not to the point you should see '10mpg' but could knock you off once in a while.

I would definitely recommend what Bubba posted earlier, however I would add the following:

What does your transmission fluid look like?
is there any grinding or howling noises from the car as you drive?
when you get out of the car after a drive, touch all four wheels (the metal part): are any of them hot?

transmission fluid color can be an indicator, but not an end-all/be-all, but a decent place to start if all else fails.

grinding or howling noises are indicative of bad fluids, or bearings, sometimes both, bad grinding sounds or metal-on-metal grinding could also be dangerously worn brakes grinding away at your car. if this is the case figure out where the sound is coming from, and fix whatever the problem may be.

if the wheels are hot after a drive, you have a brake dragging, and need to look through your braking system to figure out why.

if you aren't sure how to tune the carbs' idle mixture screws: my grandpa always recommended having individual vacuum pressure gauges on each carb, set one's idle mixture screw where you are getting the strongest vacc from it; and then set the other one as close as you can get to matching the vacc gauge, if you can't get them to match within a coulple PSI, dial the first one back 1/8 of a turn, then try to balance them again. on 3 carb setups he always did the middle carb first as it would have the largest effect on the engine.

I, Myself, heve never done this; however I am putting this here as he was an ASE mechanic for 40 years, and ran two cars on the St. Louis car show circuit for 20 of that, and was a member, and technical advisor, to the Gateway Ford Mercury car club. If this is not the way to do it, I am sure Bubba or B RON CO would tell us.

 

[bubba22349]

Excellent R_Calis, that's some great info on Performance Carb tuning that your Grandpa used and would be a very accurate way of tuning! My uncle who taught me a great deal as i was growing up was also a master of engine tuning and could balance the multi Carbs by ear listening to the car as he tuned it. I do notice that many site members seem to think that the 3 X 1V multi carb set ups of the past would have to be so hard to first tune or or a big hassle keep to in tune, which isn't the case at all. I do sometimes neglect on the how to as as in my above post on how to get to the lean beat idle which is a more of a Emissions / Economy way of tuning which is for a bit leaner idle. It's is done in a slightly different way using an old school Tach / Dwell unit by first setting the Carb mixture screw to its highest RPM then turning the mixture screw in a 1/4 turn, I then set the curb idle RPM to spec and then re tune the mixture screw again one or two additional times to see if I can get any better. I wonder what happened to the OP there hasn't been another response?

​

 

[R_Calris]

my grandpa taught me a lot, and its been almost 7 years since we lost him. well, if I am honest its been longer than that, Demintia what it is.

I wasn't sure if it was the 'right' way to do it, as he repeatedly told me that he did it that way to make sure the timing advance would always be the strongest. I did see him do it by ear once at a car show, and as soon as he was done, he told the guy to bring the car by his shop the next day so he could verify it, and make sure the timing advance was working properly, but that fix would 'get him home' there were a lot of times I saw him do things to cars, while telling the people that it would get them home, but they should really take it to a shop they trusted to get it done right, and/or verify what was done, was done right.

on my motorcycle, the mechanic takes a series of hoses, connects them to the vac ports, pours some water in each one, then tunes the carbs till the water level is the same in each tube; then begins tuning for performance after its balanced. dunno how effective this would be on a car engine, and you have to make sure the water can't be sucked into the vac ports, but it should work about the same if you can't afford the vac gauges.

its not often someone from Gen-Z can say they have replaced heads on a flathead V8, and even fewer that can remember the torque steps for all 21 bolts on each head. (I am no longer one of the latter)

and I am with you; I hope to hear more from the original poster soon to see whats up with this project.

 

[dydaktix]

These are the way's and in the general order that I check for these type of problems.

First Check for any vacuum leaks especially at each of the two Carb"s Base mounting gaskets and at the Carb's Throttle Shaft on the linkage side, these are some of the most common places to find vacuum leaks also check for leaks at others vacuum lines you might have such as for the PCV and the vacuum line going to the Transmission Modulator etc.

Next Check the SCV is working plus the LOM (Load O Matic) Distributor's Vacuum Advance Canister will hold a vacuum.

Finally if all the above items check out or if any problems that were found are fixed check that all of your 170's Tune up settings are correct

These are the important Tune Up Specs for a 1962 Ford Falcon or Comet with a 170 Six and an Auto Trans. The Firing Order is 153624

1. The stock spark plug used was a Motorcraft BF-82 set the Plug Gap .034
2. The Distributors Points can be set to a basic .025 but for best results for economy they need to be set to 37 Degrees of Dwell
3. The Base Ignition Timing is set to 10 Degrees BTDC for the Auto Trans Cars.
4. The 1960 to 1962 early Six Engines all had a Solid Lifter Cam so with the engine warmed up good set the Intake & Exhaust Valve Lash to .016 Hot
5. With the engine warmed up good do a Compression Test to determine the engines over all condition.
6. With the engine warmed up good set the Carb's Mixture Screw to the Lean Best Idle.
7. With the engine warmed up good set the Carb's Curb Idle to 500 RPM with the Trans in Drive and the parking Brake set and wheels blocked or with someone else stepping on the brakes.

With an engine that's in very good condition after its tune up is right it should give you excellent Fuel Economy of double or more MPG than what your now getting, best of luck.

Thanks for the info @bubba22349 from the classicinlines article, it sounds like the load-o-matic was mated to the Autolite, but mine apparently came with a holley 1 barrel. Does this affect anything?

 

[R_Calris]

the motorcraft/holley 1946 is what they moved to after the autolite. its not surprising to see a Moto1946 on it. the biggest difference I can think of offhand is the direction the throttle cable comes from when comparing the autolite to the motocraft. the motorcraft was usually a throttle cable that came across the engine, and the autolite was generally throttle linkage that was mounted along its length. but even that can be easily changed.

 

[bubba22349]

The stock early cars from 1960 to 1965 in Caifornia and until 1967 in the other 49 states all came with the Load O Matic Ignition System, or a LOM Distributor. The early cars from 1960 to about 1963 mostly all used the Holley 1904 and some of them used the 1908, both of those 1V Carb's were also fitted with a SCV. After that Ford used the Autolite 1100 with and without a SCV and some 1101's until about the end of 1969 when the Autolite's Carb supply was gone they went to the Holley 1940's to mainly use as replacements for them. Then Ford went to the Carter YF / YFA type 1V Carb's and lastly to the Holly 1946 until the end of the 200 small six production. For the best results you must match a LOM Distribitor with a Carb that has a SCV on it.

Dydaktix, it sounds like your car still has its stock OEM parts with likely a 1904 Holley Carb, no it's not a problem and when they are in good condistion they will work very well for a stock Load O Matic Distributor. You might post a picture of the Carb and Distributor so that we will know that you have a matched pair to work with. Best of luck

 

[R_Calris]

thanks for that Bubba. I forgot about the 1904/1908

 

[John Ha]

I had the poor mpg issue (I was seeing 10-12) with my 250 after I put it in my Mustang. I found a dragging front brake (the caliper piston had seized) and then I found that I had not set the float correctly when I'd rebuilt the carb. I also found a small fuel leak where the filter joined the metal line from the pump. Once I got those things sorted out my mpg went up a bunch. I ran out of good weather before I could get a good reading on it but it's much, much better than it was previously.