240 vs 300 mpg and power

Parker

Well-known member
Mine is a multifaceted question, so I decided to post it under the economy board.

I am planning on sniffing out a 1969-1972 Galaxie/LTD for a 240 or 300 conversion, which will serve as my backup daily driver. Not so long ago, I built one of these old yachts to a silimar specification. This time, I'll know what mistakes to avoid.

Here are my questions:
Does the 240 get any better fuel economy when compared with the 300?

Is the power difference noticeable?

Will a TR3550 5 speed or T56 6 speed transmission have any measurable economic advantage over a 3.03 toploader?

In my last car, a 300 6 found it's home under the hood. On this go around, I've seen several 240 motors for sale on facebook, and they're on average $200 cheaper than their 300 successors. I am tempted to pick one up.
Would a 240 make a good daily that is capable of holding 55 mph on the interstate, while averaging 16 mpg with 3.00 rear gearing? Speculation is welcome! Thanks for the help.
 
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Would you be rebuilding the 240?
Only if it really needs a rebuild. I usually test a motor by putting a balloon over the breather and counting how long the blowby takes to fill the balloon to a particular size.

What do you suggest?
 
The 240 has a 2.18 rod to stroke ratio versus a 1.56 ratio for the 300.
The higher rod ratio allows a higher compression ratio without detonation for a given octane fuel and the shorter stroke along with the decrease in piston to cylinder wall side loading makes the 240 a lot more efficient engine than the 300.

If you use the 1965 to 1968 240 rods with the .912” pins, there are some inexpensive cast pistons with thin metric rings that will decrease friction and heat significantly which will also add to increased fuel mileage.
 
Mine is a multifaceted question, so I decided to post it under the economy board.

I am planning on sniffing out a 1969-1972 Galaxie/LTD for a 240 or 300 conversion, which will serve as my backup daily driver. Not so long ago, I built one of these old yachts to a silimar specification. This time, I'll know what mistakes to avoid.

Here are my questions:
Does the 240 get any better fuel economy when compared with the 300?

Is the power difference noticeable?

Will a TR3550 5 speed or T56 6 speed transmission have any measurable economic advantage over a 3.03 toploader?

In my last car, a 300 6 found it's home under the hood. On this go around, I've seen several 240 motors for sale on facebook, and they're on average $200 cheaper than their 300 successors. I am tempted to pick one up.
Would a 240 make a good daily that is capable of holding 55 mph on the interstate, while averaging 16 mpg with 3.00 rear gearing? Speculation is welcome! Thanks for the help.
Hey Parker. The 240 needs to rev 25% higher than the 300 for the same power output. 3.0 gears/240 is too tall for a heavy car IMO. That's going to feel like a 2.40:1 gear if it was a 300. My 240 with a mild performance cam is stronger and more economical than the 300 it replaced, once over 1800rpm. A 240 will be weak lugging, unlike the 300 which pulls good cruising @ 1500rpm. The 240 needs to be turning at least 2000 rpm at cruise speeds.
 
Hey Parker. The 240 needs to rev 25% higher than the 300 for the same power output. 3.0 gears/240 is too tall for a heavy car IMO. That's going to feel like a 2.40:1 gear if it was a 300. My 240 with a mild performance cam is stronger and more economical than the 300 it replaced, once over 1800rpm. A 240 will be weak lugging, unlike the 300 which pulls good cruising @ 1500rpm. The 240 needs to be turning at least 2000 rpm at cruise speeds.
Good to know. I like cruising at 1,800 or so RPM. I'll dig up a 300 then. Someone in Pennsylvania has a 300 industrial motor i may go take a look at. Thank you for the input.
 
With the correct camshaft the 240 can also have a wide power band with good usable low rpm torque.
True, and this Crower grind and @-1* advanced is not at all correct for optimum low-end. Actually all my high-gear driving is below 2000 rpm, there's ample "good usable low rpm torque". I'm in flat country, Parker is in the highest/steepest region of the Appalachians, I was taking that into consideration.
 
True, and this Crower grind and @-1* advanced is not at all correct for optimum low-end. Actually all my high-gear driving is below 2000 rpm, there's ample "good usable low rpm torque". I'm in flat country, Parker is in the highest/steepest region of the Appalachians, I was taking that into consideration.
SLEEPER
FORD 240 6 CYL. HYD ROLLER CAM
.450/.450 252/252 195/195@.050
110 LSA WITH 2 DEGREE OF ADVANCE
BRUTAL TORQ FROM 1600 TO 4000 RPM THE SLIGHT HINT OF EXHAUST NOTE
MAKES ONE QUESTION WHATS IN THAT.CAN BE USED WITH OEM STALL
POWER RANGE FROM 1500-4800 RPM
 
Good to know. I like cruising at 1,800 or so RPM. I'll dig up a 300 then. Someone in Pennsylvania has a 300 industrial motor i may go take a look at. Thank you for the input.
Cruise at the rpms the engine tune wants. You don't need a tachometer. I like the idea of 1,100 to 1,200 feet per a second piston speed being most efficient. I got the best milage (36 per a gallon average) in my 98 civic ex 5 speed at a steady 100 mph/ If I remember correctly it was 3800 rpm for a 1,000 mile drive. I wouldn't do it again but that was in my younger years and thankfully I did not get pulled over because I had a suspended license at the time from selling weed.
 
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