15 miles per gallon ?

We don't get much snow here at all. If any, we might get a flurry. It is very uncommon for us to get any amount of accumilation, which is O.K. by me. When I call this car my daily driver, it does'nt mean that it is my only means of transportation. I will just drive it whenever I want.

 

I have a stock (not rebuilt) 302 with 104000 miles on it, a C4 (one of my own) and the stock rear gears and I got 21.7 on the last 600 mile trip I took. That includes running around town for the week I was there.
The biggest influence on mileage is the driver - nothing you do to your car will affect it more than the way you drive.

 

Let's see I've been working on the car about three years. I know I've thrown about 5 gallons of gas into the tank when the Comet was at my house. Two years ago I moved it to my brother's house and he has probably thrown about 20 gallons of gas into it over the two years. We have driven it all total about 1 mile. So I guess I get about 25 gallons per mile.

No seriously back in the seventies when I had my original 1971 Comet GT, 302 2v 3-speed, I kept my gas mileage religiously. I was getting 17 miles a gallon on average.

 

I checked the fuel milage on two different tank fulls,and drove the car gently to maximize the outcome.15 MPG is all it got. What compression ratio, and what ignition does yours have? I added an electronic ignition distributor and a MSD Blaster 2 coil to my '70 F-100 which had a 3:50 gear ratio, and it went from 13 mpg to 15.5 mpg on average, with no other changes. That's the reason I said that I wanted to add the electronic distributor and a MSD box and coil to this car's engine to create a much hotter spark, thus making the vehicle more economical to drive. If it worked for my truck, it should work for my car, huh.?

 

Engines back in the 70's were tuned for emissions...not mpg. The government wasn't thinking it still takes x amount of gallons of gas to get from point A to point B, all they cared about is what the tail pipe smelled like. Some of these changes involved lowering compression ratios, leaning carburetor mixtures, adding air injection to exhaust gases, and retarding cam timing. Gasoline formula has changed since the 70’s. By changing the timing advance curve inside your distributor to come in faster you can pick up more MPG and HP. By using pre-emission timing gears to get the valve timing back to where it was in the glory days will ensure the intake valve is opening closer to the top of the cylinder so it can draw more fuel/air than it does when opening half way down the cylinder.

 

I had 20mpg interstate driving 75mph on an 8 hour trip each way. fresh 306 with 289 heads roller rockers, sft cam 218 duration rpm intake full length headers. It was a blast!
I cant imagine you not getting better fuel economy with ignition and exhaust upgrades.

 

Thanks, that is some solid information. I was planning on changing the timing chain and gear set, just because. So what you're telling me is, there is a difference in '68 and a '73 timing chain and gear set as far as the positioning of the gear teeth in conjunction with the cam peg hole in the center of the cam gear ? Or would the difference be in the keyway slot on the crankshaft gear ? I would like to hear more from you.

 

The keyway on the cam gear is one tooth off, or about 6 or 7 degrees retarded on the post emission engines.

http://www.woodyg.com/fairlane/finfo/CamTiming.html

Here is a pic of a 6 cyl cam gear. The pre-emission gear is on the bottom



If you really wanna wake up some sleeping horses and get better mileage...change the springs on your mechanical advance weights. http://1bad6t.com/Maverick/maverick_27.html

 

That is 8.5 degrees - there are 42 teeth on the gear - 360 / 42 = 8.57 degrees.
That is more than the amount of advance or reterd fo any cam - although the cams are also ground differently.

My ignition is a points style distributor with stock points.. compression is the stock 8.5:1 - 8.7:1 with 109000 miles on the engine. 21+ mpg on the hiway.............
I don't know why anyone else can't get the same?...

 

fuel mileage

28 mpg .

 

rthomas771 and PaulS, thank you both for your information. I learned something from both of you guys. This information is great. I WILL be changing my timing chain and gear set, and I will be rebuilding and changing my advance springs in my distributor in my '73 and my '75. I just never realized that the advance springs made so much difference. After I make these changes, plus my MSD set up, that should make a big difference in power plus economy.

 

I thought this was for a 302? Isn't the cam thing for a 6 cylinder?:16suspect

 

Same principal applies...an engine is an engine. They work the same. Both have valves and both have a distributor. If you read the links that I posted then you would have know it applies to 72 and later 170-460 engines.

 

Any pics of this emissions v8 gear? i have never seen it....

 

Today, I decided to check everything under the hood of my '73 Maverick that had to do with vacuums. I found a few that had dry rotted ends, and were, of course, not pulling as they should. The kicker was, I pulled the vacuum advance hose off of the bottom of the carb. base to check the vacuum port, and nothing. I noticed that I had to have the distributor turned really far towards the thermostat housing for it to run freely. I ran a vacuum line from the vacuum tree on the rear of the intake to the vacuum advance, and the engine chugged right down, so I readjusted the timing by ear. I took a test drive and it seemed to run almost easier. I'll drive it a couple days, and see what the results will be.