240 vs 300 mpg and power

[Parker]

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.

 

[pmuller9]

Would you be rebuilding the 240?

 

[Parker]

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?

 

[pmuller9]

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.

 

[Frank]

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.

 

[pmuller9]

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.

With the correct camshaft the 240 can also have a wide power band with good usable low rpm torque.

 

[Parker]

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.

 

[Frank]

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.

 

[pmuller9]

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

 

[hodaka100]

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.

 

[pmuller9]

A 240 with a 300 EFI head will give you the best fuel mileage.

 

[63 Sprint]

Proper ignition curve with an MSD 6A will also help increase fuel economy.

 

[philford]

the industrial motor. likely being designed as a stationary engine might be tuned for "mileage" or economy, and steady mid range RPM's rather than power. Maybe that's just what you want to get the target of better mileage? is it propane or natural gas? maybe you can keep that too?

around here, it may be similar there but we pay road tax on gas, except for farm gas which has die in it and you aren't supposed to drive using farm gas but I've never seen anyone chek. they may in farming areas?
with propane it's pretty difficult to die it or to tell if its for your barbeque so maybe you can get away without the road tax? I remember dear old dad running his diesels on stove oil for that reason.
you might give up a little in power and range, plus having a large tank, where?, in the huge trunk maybe? it needs to be vented , I think.

I doubt its hard to change between propane and natural gas, just a different orifice maybe?

 

[Bronctopia]

you aren't supposed to drive using farm gas but I've never seen anyone chek. they may in farming areas?

Dunno bout the left coast, but here on the right coast they do check, but generally just commercial trucks. At pop-up inspection stations usually. And if they flag and pull a truck at the permanent weigh stations, they may check then as well.

 

[philford]

Ive seen roadside inspections in rural areas, but rarely. back in the 70's they omitted car testing and they did use emissions testing for quite a number of years but when they got all the cars that can actually last very long off the road they stopped. they had a bunch of programs to get older cars off the road. cityfolk don't know what farm gas is, we used to buy drums of it as we used it for boats. they would add the purple dye to the drum. If they liked you they would go weak on the dye, if they didn't know you, you probably got extra ;-)
Many just went to gas stations and paid road tax for their boat gas.

 

[Bronctopia]

Nobody farms with gasoline out here, so the issue is always off-road (red dyed) untaxed diesel.
Municipal vehicles are tax exempt, so the diesels among them usually run red fuel.

 

[philford]

Many who own a ford truck and also a little car, but then we need insurance for both which depending how many miles you drive means two insurance policies and may or may not be worthwhile.

If insurance was applied to gas, or to the driver, it would mean you can drive anything with gas in it and you have public liability insurance. if you drive more, or drive a gas hog then you pay a bit more, that encourages people to use less, without restrictions. Also makes owning the econo car as well, more viable.

My insurance here is about 100 a month for each. so I need to drive quite a lot to make it pay for that second insurance plan. If I can't save at least a full tank of gas about every 2 weeks, its not worth the extra expense of having 2 cars insured. I think I'm near the borderline on that.
they tried putting a larger enviro fee on gas here, but its messy, people don't like the concept much,, it got political. People do economize more as the price goes up.

it could be made more beneficial if owning a second car to save fuel is practical and that could have a positive net effect economically and environmentally. what Im seeing is the insurance costs affecting that balance, here.

 

[sixtseventwo4d]

With the correct camshaft the 240 can also have a wide power band with good usable low rpm torque.

How much higher of a rev limit does the 240 allow?

 

[pmuller9]

How much higher of a rev limit does the 240 allow?

It has such a short stroke that the stock 240 bottom end would be safe to 6500 rpm.
With the longer 7.130” Molnar rods and light weight pistons the 240 would be good to 8500 rpm’s.

 

[Parker]

the industrial motor. likely being designed as a stationary engine might be tuned for "mileage" or economy, and steady mid range RPM's rather than power. Maybe that's just what you want to get the target of better mileage? is it propane or natural gas? maybe you can keep that too?

around here, it may be similar there but we pay road tax on gas, except for farm gas which has die in it and you aren't supposed to drive using farm gas but I've never seen anyone chek. they may in farming areas?
with propane it's pretty difficult to die it or to tell if its for your barbeque so maybe you can get away without the road tax? I remember dear old dad running his diesels on stove oil for that reason.
you might give up a little in power and range, plus having a large tank, where?, in the huge trunk maybe? it needs to be vented , I think.

I doubt its hard to change between propane and natural gas, just a different orifice maybe?

I was actuality planning on running the car on woodgas. There were around 50,000,000 metric rumptons of good hardwood trees dropped here by Helene, free for the taking by anyone with a chainsaw. It's a shame to let it all rot to waste.
An industrial engine would be ideal, but finding one is nearly impossible.