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I just put in a NEW ENGINE--then put in a Tornado Gas Saver on top of my carb. I bought a K & N Airfilter--keep 42 PSI in the tires turned off the engine at intersections with lights that exceed 3 minutes in time. Needless to say I have reduced my trips in my elky. I have a 85 305 auto and never run the air. Now I just found out where I lost 22% of my mileage. Yesterday I filled up with 18.5 gallons of gas I figured I went 167 miles all in the city. That is 9 miles a gallon. Before the Tornado and K & N Air Filter it was 155 miles or 8 miles a gallon. After looking at these numbers I told myself there is major problems here. That is the same amount of mileage a v10 engine receives. The one item I believe allot of us over look is the odometer, when figuring out our Gas Mileage. So what I did was go to Map Quest and I typed in my home address and an address some 2.9 miles away. This was my first try so I was going to the post office anyways and Map Quest said it was 2.9 miles away from my home. OK--I first wrote down my current odometer reading and then the odometer reading at the Post Office. Sure enough there was a .66 of a mile discrepancy or 22.75 % . So using this figure 167 X 22.75 is 38 miles. Added to 167 is 205. So my real gas mileage is 205 divided by 18.5 is 11 miles a gallon. Which is still poor but allot better the 8 miles a gallon. I suggest anyone with 7 to 9 miles a gallon gas mileage do the Map Quest progam to figure out the distant and compare that number with your odometer..--Email me if you discover you found where some of your gas was going.. jackboots@earthlink.net

I'd ask "Do you have factory wheels and tires on the truck? Do you have factory Transmission and rear end gears in the truck?"

Going from a P235 to a P245 will effect the speedometer. Definatly going from a THM 350 to a THM 400 or 700R4 will effect the speedometer. Changing from 2.73 to something else will effect the speedometer.

All that changes the drivetrain. Over inflation of your tires will cause them to be larger at speed then normal so that will effect the speedometer also.

The speedo is a mechanical device with tones of dependancies and it will never be accruate it will be close but not accurate at all.

I get roughly 17 Miles per gallon in my 93 Silverado Pickup extended cab sport side. So if your getting 11 MPG in your elky with a 305 then you need to work on it some. Granted, I have an L60 overdrive in the pickup but it is a lot bigger and less wind resistant then your Elky and the disparity is still too much.

All that smog control is old and possibly choking the crap out of the engine. My 383 gets over 11 MPG in my Elky and I now have a L60 (700R4) in it, I also have a 3.73:1 gears with 26" tires. I'd say I am doing about the same as my Pickup but..... I haven't ran a check on it yet. I am getting roughly 300 miles to a tank of gas (22 gals) so that puts me at around 13 mpg just rough figuring.

THANK YOU PETE!!!!!

You have given me a grocery list and I will start with a HIGH FLOW CAT and continue from there. In my opinion Gas will range from $1.65 to $2.00 gone are the days of $1.21 to $1.39 ( IN San Antonio, Texas ) . Again thank you so very much for your imput..