Potential MPG of a 300 Galaxie?

[Parker]

Even with the 3:1 first gear, dragging the clutch on take off is required on my truck. It's difficult to back a trailer, or anything requiring slow speed maneuvers, it requires clutch abuse from having to slip it constantly to effect. Where you live, moving that heavy car with a 3.03 and 2.75 gears will be an annoying experience. Pulling away from an up hill stop without stalling will be a challenge. With the clutch out in first, only 1000 rpm at 10mph. You could go about 50mph in reverse.
I'm not big on spending someone else's $ or giving advice- but with the work you're putting into this unique build, a rear-gear swap needs to be included.

Yeah that's definitely on the table of things I will do once it's running. I'm gonna throw the old clutch in and wear it out, then replace the clutch and swap gears.

 

[bubba22349]

What about a drop-in electronic points conversion kit? I have one in the glovebox from the last guy. He was going to install it in the old v8 before it blew. I had never heard of one before.

Yes those conversion Kits can work fairly good if the Distributor is still in good shape. But if that one in your Glove Box was made for the Chevy V8 that was in it, than that's not likely going to fit and work in a Ford Six. The PerTronix # 91261 fits all 1965 to 1974 Ford 240 or 300 Six Distributor's. The one bad thing thought for most of the stock 1965 to 1967 Ford Six's were the old Load O Matic Distributors, if yours has the 1968 to 1974 than you would have a Duel Advance System and your all set.

 

[Frank]

What about a drop-in electronic points conversion kit? I have one in the glovebox from the last guy. He was going to install it in the old v8 before it blew. I had never heard of one before.

That's ok. Or you can use points fired by the EFI ignition module.

Upgrade Points Distributor To Fire With A TFI Module

Converted my wife's daily driver to points-controlled electronic ignition using a Motorcraft ignition module off a '93 F150. Credit for this swap goes to gofastforless.com. I emailed the man who wrote the site to verify a couple of specifics, and he responded, which I appreciate. The goal of...

fordsix.com

 

[Parker]

That's ok. Or you can use points fired by the EFI ignition module.

Upgrade Points Distributor To Fire With A TFI Module

Converted my wife's daily driver to points-controlled electronic ignition using a Motorcraft ignition module off a '93 F150. Credit for this swap goes to gofastforless.com. I emailed the man who wrote the site to verify a couple of specifics, and he responded, which I appreciate. The goal of...

fordsix.com

Thanks, Frank. I was just looking for your post about this.
My memory fails me sometimes.

 

[Lazy JW]

So apparently, with the 2.75 gear, this barge is going to be an absolute DOG until I hit about 30 mph, am I getting this right? At 55, it's just past 1750 rpm. Is this where the torque is? I've never driven one of these enough to know how the motor likes to behave.
The only thing I know is that it was an EFI, and it hated being lugged under 1700 RPM.

So cruising MPG doesn't look too bad so far as prospects go - am I screwed at anything around town? How well do these engines do on take off from a stand still? I'm mostly worried about stalling on slight hills when starting out. Do you think I'll have to slip the clutch?

I'm up for the challenge just to say I've done it with 2.75 gears. Most of my driving is to commute 18 miles to work, 55 all the way. Eventually, I'll have to drop in something a little shorter.

You will be quite happy with those 2.75 gears most of the time...

I owned two F-150's with 300-6 T-18 2.75 gears and they were very good on the highway, not much fun in stop-and-go traffic though. Of course I had that delightful granny gear when needed.

 

[PSIG]

Agreed on most of it, and I'd expect 15-18 mixed/20-23 highway with a reasonably tuned carb 300. EFI would push this up mostly due to sharper practical tuning and better holding of tune in conditions, for perhaps 20-23 mixed and 25-27 highway at 55. 65+ mph will suck much more fuel with the much higher drag. No matter how you feed it, tuning is a requirement for maximizing anything from economy to power.

I also agree the gearing won't affect the MPG much, as there is a trade-off between peak-torque economy (best engine breathing) at higher rpm, versus the reduction in parasitic internal engine drag at lower rpm. So, perhaps 1800-2200 (or higher) is a good range for the engine to be happy. By moving to a steeper gear, the MPG won't change appreciably due to this, but the driving should be more enjoyable. Local MPG may increase due to less required throttle in stop-n-go around town. I'd definitely gear it down, but that's me. Do you.

As a random but personal experience, we swapped a healthy street car's 4.11 gears for 3.25s to make a road trip. Oops. Economy fell as the rpm were too far below the cam's happy range. With the 5-speed, we made most of the remaining trip in 4th to get the economy back. Your example is similar but different. Lower rpm is not always better, and should be coordinated as a package. Only make compromises to meet your goals.

 

[Parker]

You will be quite happy with those 2.75 gears most of the time...

I owned two F-150's with 300-6 T-18 2.75 gears and they were very good on the highway, not much fun in stop-and-go traffic though. Of course I had that delightful granny gear when needed.

Thanks for the detail. I dropped a 5 speed 3650 out of a Mustang into my Crown Vic, and with the 3.27 gears, if I only use 2nd, 4th, and 5th gears, it has ratios similar to the 2.75 with a toploader behind it. Slow, but steady and reliable - and I don't need to be getting any speeding tickets now do I? As long as I've got that low end torque, I doubt the 2.99 first gear will be much of an issue.

If it's truly miserable to drive, I'll find a 3+1 .80 O/D cast iron toploader out of an econoline or something. They're not all that rare. Heck, maybe even a T5 eventually.

Were the T-18's any good? What about overdrive options?

 

[Lazy JW]

Were the T-18's any good? What about overdrive options?

The T-18 is a cast iron heavy duty boat anchor truck transmission with non-synchro granny gear and a great big tall long-throw funny-looking floor shifter sticking out of the top; high gear is direct drive but a Gear Vendor$ overdrive can be attached.

Never heard of anyone installing one in a car.

 

[Bill56]

The T18 is fine... if you have it in a truck that will be used to actually haul stuff.
It's major claim to fame is in being able to use that very low 1st gear to get a heavy load moving without abusing the clutch.
I think the 3 speed will do the job with the 2.75, but won't be much fun.
Since the 300 has a small block bell housing, it should be simple enough to bolt up a T5 just as if it was in a Mustang.
If you run that with a 3.50 or 3.73 it will have a more leverage to move that full size Ford and work out better if you start adding goodys to the engine later.