I know this forum is about performance but for me that means Low end Torque. I have a 95 F150 with a Mazda 5speed OD. I love this truck and I use it to pull Trailers in Baja. now I have been doing this for 20 years and I have tried just about every combination of equipment Ford has made. the 300 six is by far the engine most suited for what I do. with as many low gears as possible and a couple high ones for when I finely get to see some highway. most of the time I am driving I am going under 45 and under 2000 RPM I never ever get over 3000 RPM and the only time I get over 2000 is when I am going down steep grads and using the engine to brake.

my question is do any of you know what Mods can be done to the 300 six that will increase ? I mean between 700 and 1700 RPM I don't care about anything over 2000.

 

You could look into a different cam. The 300 was built for low end pulling to begin with. If you had a carb there are kits to mount a 4bbl on it.

 

It's about as good as it gets, bone stock. But read the RESULTS pages of Project MPG. I noticed worthwile improvements from a K&N drop-in, and intake insulation.

 

In that low rev range there really isn't a lot more you can do without major changes, being that the engine was made with primarily low end torque in mind.

Even the newer inline engines with variable valve timing and all kinds of electronic goodies have a hard time duplicating the low end torque of the 300. They make good torque at higher revs, but for your application that wouldn't do you any good regardless.



And although a lot of questions here are more performance oriented, most people are just as helpful regardless of what type of performance you want to improve.

 

This truck is 100 % factory stalk right now and has only75,000 miles on it, and it is in excellent condition.

some things I am going to do right away are.

1 change the Mazda five speed OD transmission for a ZF. this will give me a heaver duty higher torque Transmission and a much needed lower first and reverse gear. it also has a Little bit higher ratio in 5th OD about .76 as apposed to the Mazda's .80, this is nice because it will allow me to go to a lower rear end ratio.

2 change the 2.73-1 ring and pinion in the stalk 8.8 rear end to a lower ratio. I am still trying to figure out the optimum ratio. Maybe 4.11 or 4.56

3 I am looking in to cam shafts, sum suppliers have low RPM high torque cams but here is one place where I really need help Crane and isky and all the rest make lots of claims but I want honest input from people that are using these cams. so I don't end up doing the job 5 times. the problem is few people use these cams. most want to build the 300 for racing, and I have done that and been there.

 

You know, for what you are doing and the very low gear ratios you seem to want, you might come out ahead by swapping to a 4x4. Even if you add a transfer case to the 2WD you can take advantage of the lower ratios when you need them, yet still get the higher ones for the times you do get on open road.

With rear end ratios as low as you are thinking about, you're going to run out of gear really quick when you do get to some open road. In 4WD low, even the 302 has plenty of low speed torque.

 

signmaster is right. The slightly higher OD of the ZF won't come CLOSE to making up for the 2.73->4.11 swap. Your top speed will be 2/3 of what it is now: that means roughly 60mph max.

Take it ONE step at a time. You know the Mazda is a problem. Swap to the ZF & then drive it for a while. You won't waste any effort by doing the rear end later. I bet the ZF does everything you need. I have an NP435, 3.08 gears, & 32" tires, and I have no trouble towing 10,000 lbs or hitting 105 mph.

 

4.11 is just too much gear for a 300 unless you're running big tires. The ideal combination is probably going to be the ZF and some thing like 3.55s

 

allot the Cams I have checked that say they will increase low RPM toque have basically original equipment specks. so I don't see where I will gain much there. with that said it looks like the engine will be staying stalk. as for tires I don't like real fat ones. but I will go to a 265 75 15 Lode rang D or better. a high profile tire is more resistant to road hazards and works well for me. I have considered using a transfer case for the low range and that is a possibility. this would be very handy for those long steep down grades. I don't want or need 4X4 it just seems to be more things to go wrong and to maintain and it adds a lot of Waite. so it looks like for now I am going with the ZF then make a couple of trips and see how it does.

 

Those 265/75-15s roll at about 680 per mile vs. 720 for the stock tires. That is going to hurt your performance a lot.

Right now 65 MPH in OD is about 1700 with 2.73s and stock tires.
Swap to the 265/75s and it drops to around 1600.
Swap in the ZF with it's taller OD and the bigger tires you're looking at about 1540, which is too low for performance and quite probably too low for economy.

With that combination of tires and tranny, you're going to really want 3.55s or possibly 3.73s

 

yes and I am thinking possibly of going to 285 75 15 so we are moving closer and closer to that 4.11 set, but the 3.73s looke good.

I might have located a ZF with transfer case. do you see any problems with swapping it in? how would I get it to shift HI to low? I know I'm going to hack more drive line, but that is no big deal.

I relay appreciate your input on this you are helping me more that you think.

 

Ya just pull back on the stick



If the ZF came from a 351, just bolt er on and move the crossmember back.

Adrianspeeder

 

I notice yours has a manual shift. do you know what years came with manual shift and which years came with the electric shift?

 

All years were standard with the manual shifter. Electronic Shift On the Fly was optional with an automatic tranny from '87 on. I prefer the manual shift.





Adrianspeeder

 

The Tirerack doesn't show 285/75-15 as an existing size.

The closest is a true LT tire not a P-Metric (which is probably better for the Baja anyway) 32 x 11.50-15 which is pretty tall and rolls at about 655 per mile. That is probably about as big as you can go on a stock height 2WD without things rubbing.

That would give you about 1430 at 60 with your present tranny and gears. Not good.

Go to the ZF and it drops to 1360. Even worse.

To get to 2000 at 60 with the ZF and those tires you'd need the 4.11s

EDIT:
I had my brain partially turned off on the above all those RPM figures are correct for 60 MPH, not 65 as I originally posted. It wasn't a good day at work.