It's been many years since I've had a pickup with the 300, but from what I remember I prefer it to the v8's. I have been trying to decide if I should put the 390 that was in my '65 F100 when I retired her, or switch to the 300 that came with my '66 parts truck. If I go with the 390 I'm going with 3.00 gears, but was wondering if I could get away with them with the 300-6? Or should I go with the 3.50's I have.

Eric

 

Auto or stick?

 

Towing or hauling or mostly street use?

 

Hilly terrain or flat land?

 

It's the factory 4sd with attached transfer case, this one won't do any work, it will be a toy and my daily driver and hit the dunes on the weekends, and it has low range for that.

Eric

PS; I live on Cape Cod, there are no hills to speak of.

 

What size tires?

 

Snows will be 29-30" mud and snows, beach and road will be 33" at the largest, I also have a set of 32".

 

Best bet is to stick with 3.50's at the very least for both motors if the 2 gears are the only option right now. Then plan on 4.10's for the 390.

Here's a gear calculator for you to play around with. Keep in mind, the 300 will max out around 2800 rpm, the 390 will be significantly higher depending on the build. There's a 12% difference between the 29's and 33's. You have sorta created a wide range with no specific answer here. I suggest for you to run the 3.50 / 3.54's and report back...

Gear Ratio Calculator

 

I drove it on the street and the beach with the 390 and the 3.50 gears for 10 years and it had way more power than it needed, so the 3.00 is a definite if I stick with the 390, I don't race, and the 390 had plenty of torque off the line, but revved a bit high on the open road. Was getting 13mpg. I'm hoping the 3.00 will improve the mpg, time will tell. My only question is if someone driving a 300-6 now thinks it has the torque to pull off the 3.00 on the road, it has the granny low and low range to handle the off road.

 

Here's what *I* know: my F-100 with 240/LD 3 spd., 235/75/15s and 3:50 gears pulls quite well, AND keeps up on the highway, 75 mph is easy, much more than that and the old truck steering dynamics tends to temper one's thoughts towards slower speeds. Notes: tires are too tall, and first is a long gear with this trans. Still the additional torque of the 300 would only prove better.
MPG:
It's a brick. Aero is a no-show. MPG won't be. That said, the 300 should be better as the FEs were not a good design for mileage; Ford sixes were always better, even when similarly sized (300 vs 302).

Then again, YMMV.

Cosmo

 

Absolutely not. Unless you plan on grossing over 10K pounds all the time, 4.10's should not even be a consideration for either engine with the tire diameters we are talking.

My old man runs around in a '64 F100 with a 262 and 3.25 gears and a T98 4 speed and 30" tires. Still takes off in 2nd gear. Cruises at 70 - 80 great, doesn't have to shift down until you get over 4% grade.

I run around with my 416 (think of a very healthy warmed over 390) and 3.31 gears and 32" tall tires behind a manual. Cruises 70 to 90+ MPH great and I have never seen the truck weigh less than 7500 pounds. Only have to shift down when I am going less than 65 MPH and need to blow someones doors off.

If you are going to normally be running 33" tall tires and never drive over 70, I would go with 3.50:1 for either engine. If you want to run more than 70 MPH for extended periods or will normally be on 29"-30" tires, go with the 3.00:1 gears for wither engine.

Either engine with a decent cam and compression will be similar in low end torque output, the 390 will just outdo the 300 once you get over the 2500 to 3000 RPM range.

 

Thanx guys, that was the info I was hoping for. I already have a spare 9", so I'm going to do both, then I'll hold off on the Dana 44 until I drive it with the 3.00 gears. If need be, I'll track down another 44 and have both setups, one for each engine if that's what it needs. After all, it's just a toy.

Eric

 

I put a 9" with 3.00 gears in my '66 with a 240 and 3 spd untill I figure out what I did wrong in rebuilding my dana 44 with 3.50 gears. When driving around town, I've noticed is that I spend more time in 2nd gear, in the higher rpms. When I had the 3.50 axle in, I could shift into third. Definatly like the 3.00 on the highway

 

How was it taking off from a stop? Any idea what it got for mpg with the 3.00?

 

Greetings from Mississippi.
If it helps any I just bought the rear axle & a SROD from an '80 F100 w/ a 300 & the rear axle ratio is 3.5L.