Parker
Well-known member
I'm going to drop a 300 straight 6 into 1974 Galaxie. The transmission is a 3 speed 3.03 toploader, no overdrive. My rear end is 3.55 if I remember right. (WRONG - the axle tag says it's 2.75. Freakin smog years geez.
What kind of MPG can I expect at 55? 15? I may get a gear vendors to bolt on the back of the transmission eventually. Since the car sits a little lower and sleeker than the f100, I was hoping it would be better thsn stock for the truck. The old 351 that came out of this Galaxie probably liked the gas too.
A cheap solution for better mpg would be to drop in some taller gears, like a 3.05 or 2.73 if the 9" ever came with those options. I woukd think that the torque of the 300 should have no issue propelling a 5,000 lbs car along with such a tall gear. Any thoughts?
EDIT: With my newfound knowledge of the actual axle ratio, I'm getting these following calculations regarding RPMs, with a (assumed) transmission ratio of 2.99 in 1st, 1.72 in 2nd, and 1.1 in 3rd:
Gear | Speed | RPM
1st, 5 mph 478
1st 10 mph 956
1st 20 mph 1912
1st 25 mph 2390
2nd 20 mph 1100
2nd 30 mph 1650
2nd 40 mph 2200
2nd 50 mph 2750
3rd 40 mph 1279
3rd 50 mph 1599
3rd ~55 mph~ 1758 (In torque band?)
3rd 60 mph 1918
3rd 70 mph 2238
3rd 80 mph 2558 - Okay, come on guys it's a 50 year old car with screw ball steering and rear drum brakes, there is no way I am going this fast...
Yet.
What kind of MPG can I expect at 55? 15? I may get a gear vendors to bolt on the back of the transmission eventually. Since the car sits a little lower and sleeker than the f100, I was hoping it would be better thsn stock for the truck. The old 351 that came out of this Galaxie probably liked the gas too.
A cheap solution for better mpg would be to drop in some taller gears, like a 3.05 or 2.73 if the 9" ever came with those options. I woukd think that the torque of the 300 should have no issue propelling a 5,000 lbs car along with such a tall gear. Any thoughts?
EDIT: With my newfound knowledge of the actual axle ratio, I'm getting these following calculations regarding RPMs, with a (assumed) transmission ratio of 2.99 in 1st, 1.72 in 2nd, and 1.1 in 3rd:
Gear | Speed | RPM
1st, 5 mph 478
1st 10 mph 956
1st 20 mph 1912
1st 25 mph 2390
2nd 20 mph 1100
2nd 30 mph 1650
2nd 40 mph 2200
2nd 50 mph 2750
3rd 40 mph 1279
3rd 50 mph 1599
3rd ~55 mph~ 1758 (In torque band?)
3rd 60 mph 1918
3rd 70 mph 2238
3rd 80 mph 2558 - Okay, come on guys it's a 50 year old car with screw ball steering and rear drum brakes, there is no way I am going this fast...
Yet.
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