SHIFTING FROM A STOP WITH HEAVY LOAD

Um, actually, no, a Cummins was/is a whole different animal, I always "babied" a Cummins, and got hundred's of thousands of miles out of them. Most of the old Detroit's I drove, and several V8 Cats, 2nd most worthless motor, without turbo's, and the "supercharger" actually wasn't a supercharger. All it did, was blow out the exhaust faster ( hence blower) Thanks for not taking that the wrong way, it's just at the time, that's what was out there. The biggest motor we heard of was the 350 Cummins, or the 400 Cat, mostly for OTR trucks.The nice thing, is everything after those 238's was an improvement.

 

I'm a BC Cummins man. You know what they need when they need it and do the proper maintenance and you will get good service from one. When the time comes to change one out they are readily available for around 10k. Can't beat em

 

yah,i don't believe detroit ever referred to the blower as a supercharger. when they are cold you gotta crank em in shorter bursts,and wait a few seconds in between to let some air get in the holes or they just crank and crank needlessly.

my point up there was....people seem to think if the old detroits were revved below 1800 rpm they blew up,and its just not true. but the minute a guy says anything all the old guys think im picking on how they drove theirs. its a 5" stroke motor,so yeah they can rev. but they weren't so intolerant of being pulled down,especially the later ones.

sometimes i think the younger crowd likes to pad their cred by talking about how they flogged them old 2 strokes,when all they did was back trailers into a dock in a parking lot with one.

 

I have an early series 60. If I let it pull down to far, then I get behind the power curve all the way down. I look at 1,400 as being as low as I let it wind. If I let it pull down to 1,300, I'm dropping gears the whole hill. If I drop at 1,400, it will hold at the higher rpms.

 

I normally drive a Cat 3406b and Cummins N14. There's no way in the world you could shift them at 1,000 rpm, unless you are headed down a big hill. On both engines, it's best to keep the rpm between 1,200 to 2,100. You get much lower than 1,300 rpm, you are lugging it too hard.

 

Torque is only part of the equation. Horsepower is the other part.

The engine on my truck has a part number plate. It says the maximum horsepower is at 2000 rpm's. You won't get close to maximum horsepower if you are lugging at 1200 rpm's trying to rely on torque alone.

I have been blessed to drive hundreds of different trucks over the last year. Almost all of them are specced for off road driving, with gear ratios north of 5. You DON'T shift at less than 1800 rpm's on an upshift. You DON'T get below 1300 rpm's unless you want to lug it and threaten to stall out. Governed speed in high gear is typically 1800 rpm's.

Every truck is set up different. Turn OFF the radio and LISTEN to the engine. The truck will tell you when you are driving it correctly.

 

I have only run B model CATS my whole life. Every Trans arrangement you can think of. Though we are seldom heavy. 110k gross to 80 .

Progressive shifting is the only way to go.

 

back in my early days- I Got a Mack R-Model with a 350 spin backwards..How I did that was I Hooked to a railvan that was heavy as heck...Popped clutch-She Died- Cranked her back up and spun backwards- Black smoke out the air cleaner housing......And you cant throttle it the same as if spinning normal

 

Hey wore out,

If I start at 8am- Can I get the trans removed,Flywheel,Rear main replaced-Reman trans-new Clutch clutch brake and everything buttoned up with no tower leaks within 8 hours? (Done by Suppertime)

No,I don't move fast-AND My help is limited-

 

Listen to the motor. Do it by feel. Every truck is different. Use common sense.