B model gear ratio

[doubleclutchinweasel]

I tjhink it will struggle to keep up 75 mph with one car on. My GCVW is around 27K lbs and 65-70 is comfortable to run with 4.10 gears. Just runs outta power trying to keep up any faster speeds and it will not pull hills well. I can use my last OD and pass someone and run it up to 75 or so on level ground, but it just doesn't have the power to keep it there.

Therein lies the problem, doesn't it?

The speeds are there, but the torque isn't.

[nasty51ford]

Yeah, was a little concerned about that, but I figured the truck by itself and just one car wouldn't have a problem, with 505 - 527 lbs of torque, my next question was going to be, how do you turn the pump up to get a little more power without going overboard and melting the pistons, or washing down the cylinders ? I remember back when I was young there were guys with these old B models running like mad with the pumps turned up on them, I had a fast "80" Pete, I was running late to get loaded, and was running about 90, I saw a sparkle in my side view mirror, looked and I could make out the unmistakable grille and headlights of an old B Model, he was coming down off a grade on 27 coming into Clermont in Florida, and he was gaining! Lol. I put my foot down into the pump hard in my 400 Cummins, and it was turned up A LOT !, and pushed it up to 97, that's all she had, we started pulling up a slight grade, I figured, "he'll drop off now" ...............NOPE !! He kept gaining, by now I could see it was a beautiful old B61, Not even a B73, or 75! All I could keep saying to myself was "WHAT THE F@CK??!!" Lol !! When he finally got up alongside of me, there was an older man, looked to be in his early 70's, and that Mack was a beautiful red, chrome grille, chrome bumper, twin chrome 6" straights, Full chrome rear fenders, and lots of other chrome, and it was barking louder than my 400, which had straights also, and man it sounded SWEET! All I could figure was it must have had a 300 stuffed in it, but couldn't figure out how the hell he would cool it if it did! He was pulling a dump trailer, and it was a SINGLE AXLE tractor !! He just smiled at me, shook a finger pointing straight ahead of him, and motored on by! I won't forget that till the day I die! Lol ! I also remember my dad telling me in the old macks, I guess the LF's and LJ's, that they would tie a wire on the rack on the pump? He said when they were pulling a long, or real steep hill, they would pull on that wire, which would open the rack, but he said you had to be careful or you could blow the engine if you held;d it too long, or too far open. Maybe that was the Lanova engine? But, I figure if I can turn that pump up just a little, it would help, plus I'd like to see the fire come out of the stack at night! Lol "stacks" eventually

[Freightrain]

Depends on the pump. I turned mine up years ago. It ran well but only got about 4 mpg. Once diesel got to $4/gal I dialed it back and get about 8mpg now. It is not as snappy off the light but gets me there. Just a light haze out the pipes under throttle. Never got fire, but never really tried.

With no oil cooled pistons I'm sure you have to be careful. Don't have the money to put a motor in it so I keep it easy on it.

[nasty51ford]

I crawled back under there this afternoon, the only number I could find on the driver side of the transmission was a little flat boss on the bottom side of the main trans, just ahead of where it bolts together with the back box, it reads 47 over 62, does this mean anything?

Thanks

Keith

[Freightrain]

Nope. Should be a nice flat pad on the side if it is a Mack transmission. Did you see the Mack script on the side?

[Maddog13407]

my 707/711 has decent power bobtailing empty with 4.00 gears and a triplex but usually a good hill will make you drop it back into low. im sure with one car on you could get 55-65 comfortable but you are never gonna see 75

[nasty51ford]

Yep, it has the Mack script on it, but that is the ONLY number I can find, guess I'll search some more! Lol