I am thinking about hooking up to the sled at the local fair this year with my 79 F250. It only has the 351M so I'm not expecting much out of it. It has dana 60 front and rear with a 3.54 gear ratio. It also has a granny gear. I will be running 33'' tire.

My question is do I want to use granny gear in low or high lock or do I want to use 2nd gear in low or high lock?

I've never hooked up to a sled before but hey there has to be a 1st time for everything. My 6 and 10 year old son will enjoy watching me place probably last! LOL

 

I used to pull with mine years ago,I always used 2nd gear and low range and it worked well.It is a fun and addicting sport.

 

Would granny gear in 4HI be about the same gear ratio?

 

First high and second low are essentially the same. There's no reason to pull the high side. You're much more likely to break parts in front of the t-case that way.

-Jared

 

I did not know that high on the transfer case was weaker than low range. Things like this is why I'm asking questions on here, to learn.

So, I would'nt even want to think about wanting to use granny in low huh? Would the wheel speed too low or something?

 

It's not that the high side is necessarily weaker than the low side. Think of it this way. First gear is around 6:1 and second is around 3:1. When using the high side the transmission output shaft, yoke, middle driveshaft, and transfer case input shaft are having to deal with engine torque multiplied by 6:1. Using low range allows those components to see roughly half of that, with the transfer case multiplying torque the rest of the way. The output shaft of the trans in your highboy is actually pretty small, and would probably be the first thing to break if you were to pull on the high side.

All that being said, you probably won't break anything with your 351m. I pulled mine with the stock 400 a few times and had a blast. My best suggestion would be to use some smaller tires if you can. That'll help you get some rpm, and it will be easier to get out of the hole. Make sure to post up some pics and vids. I love watching old fords pull. Good luck not getting addicted.

-Jared


Check out this thread too.

https://www.ford-trucks.com/forums/753370-pulling.html

 

Thank you for the info! Info like this is what I'm looking for.

 

The biggest factor is going to be track conditions. For a sticky track 2nd/low, for loose track you'll need wheel speed, 3rd/low.

Typically run more tire pressure in the rear and about half in the front as well.

Josh

 

I'm building my 1975 High boy up to pull sled, but its also getting a powerstroke, a divoriced NP205 and other stuff. But 2nd in low range loc is what you want to do. That what most guys around here in the gasser class do.

 

7.3, 6.0 or other Powerstroke?

I am also getting into the pulling game. My dad was heavily into it late 70s into the late 80s. But I think I am going to do a 1993 7.3 IDI.

Josh

 

Third low is absolutely out of the question, regardless of track conditions. Not unless you want to see one hell of a smoke show coming from the bellhousing. You won't get the sled to move, I guarantee you that. The tire pressure suggestion if worth noting.

-Jared

 

Dully noted, I forgot the OP has a stock 351M, I was thinking supercharged big block or Diesel.

Many here on a loose track run 3rd, a lot of diesel guys are using 4th.

I would reckon 7 out of 10 gas engines use 2nd/Low.

I wished truck/tractor pulling was at least half as popular here in Colorado as it was in my home state Kansas. Every weekend in the Hutchinson/Wichita area you could catch a truck pull, not to mention all the dirt circle track races.

Josh

 

@ Bullitt: If you read my sig lol its a 7.3 from a 95, they are bulletproof (Ford dalerships will tell you that) but its getting the whole treatment, turbo, big injectors, nice IC, nitrous, methanol, and custom tunes for street and track =D its going to also be a dually.

 

I have been commenting today on an iPhone which doesn't show signatures...

Josh

EDIT: and oddly as I get on my laptop my sig doesn't show up in this post? Hmmm...

 

As long as you don't let the truck start bouncing bad you are not going to break anything. You will find out quick though if you have a bad or weak u-joint, lol.