149 engine teardown for cam replacement

[dodge trucker]

Originally Posted by J-Mech

I do. I have one that goes down to 5ftlbs.

I also have an inch pound that only goes up to like 50, and I also have a 3/4" drive that goes to 600ftlbs.

I have at least 4 torque wrenches....that I remember.

Yup so do I.... but you and me aren't the ones doing this particular job that the thread is about.... that question was meant for the OP.

People don't realize but converting units of torque is often one of those ideas that is better on paper.

Without looking back within the thread, I think there was some in/lb measurement that came out to (something like) 23.6 ft/lb. I'll use that figure for argument's sake.

In/lb. is a much "finer" scale than ft/lb. which is kind of "coarse".

The whole reason for torqueing something to a certain setting is to control distortion, tighten evenly/equally, stretch the bolts to optimum and not beyond, and also to not "strip" any threads. Sometimes you can go past that prime point of "tight" and not realize that something is starting to strip out until it is under stress, from thermal heat/cold cycles to mechanical "work". If not done right, you might as well use a plain ol ratchet and socket. Sometimes approximating by using a coarser scale, isn't any better than not using a torque wrench at all.

I, too, have several torque wrenches from the old Craftsman beam style, to 3-4 clickers in between, up to (probably the same) 3/4", that goes to 600 ft/lb that Jon has. I have both in/lb and ft/lb and even a fancy expensive digital one that I can change units on, just by pushing a button. The snap on guy really liked me that day, ha ha....

One thing to keep in mind here, is that most torque wrenches are NOT ACCURATE in the lower 20% OF THEIR SCALE> which often starts somewhere other than zero.
On one of my Snap on clickers, it goes from 20lb to 250 ft/lb. So 20% of 250 would be 50 ft/lb. But the scale starts at 20.
so 250-20=230 lbs of "scale" 230/5= 46. so for the 1st 46 lbs of scale that torque wrench isn't as accurate as it is in the top 80% "of scale". So we add 46 to 20 (the lowest the scale reads) we come up with 66 ft/lb. That is the lowest reading to which that torque wrench can be "trusted. almost 3x the "converted" in/lb. to ft/lb number that you are dealing with on that rod spec. and then if the reading is to be 23.6, how do you know if you got 22.8 or 25.1 ft/lb? and are both exactly THE SAME? Sometimes "close enough," isn't.

I completely understand, we all had to start somewhere, and most had basically "nothing" when we did start working on things (some had access to tools at work, or at Dad's garage, or the neighbor, whatever) and I also completely understand not wanting to buy a tool to be used one time and then collect dust. Been there many times as well. BUT when we set out to do a job, we set out to do it right, the best that we can. and in a case like this, if the job doesn't last, most likely nobody will get physically hurt (tractor engine blows up, you hear a boom... but no bloody limbs and such) but the time it takes to do it right (and I am glad to see you asking questions to help be sure it is, in fact, right) isn't much more time than to do it haphazardly... but the difference in results, and how long they last, can be HUGE. I myself hate redo's. Yes you still learn from having to redo a job, and maybe more so than it everything turns out like you hope and expect it to. but for what it costs to have to redo something, that's what hurts....

I'm saying all of this because though Jon hammers on some of the details like your piston to wall clearance, there are certain fasteners that need to be tightened "just right". and by converting in/lb to ft/lb and the result being that low on the chosen scale, it is extremely hard to be accurate.

In this case you would be better off begging, borrowing, or (no, probably not stealing) a torque wrench of the scale you need for the job at hand.
At very least I'd be watching garage sales, auctions flea markets and such for some of these tools that you need but not all that often. if only for "next time".
I am NOT AT ALL a fan of Harbor Freight but in a case like this for what you think might be a 1- time deal they can be handy. Never know, if youre like the rest of us your 149 won't wind up being your "only" Cub, you'll use this stuff again!!!

Having said all of that, I appreciate reading threads like this of somebody "digging in and getting their hands dirty" instead of today's mentality of either A) "throw it away and get a new one" or B) "let someone else do it for me, and I'll just write a big check"...and it appears by your questions, you know your limitations/ believe me, we all have them.... but for all the work it takes to do a job like this, if you want it to last another 20 years, heck even 5 years, you gotta do things right.
The most important fasteners to torque "the right way" on one of these engines, is the rod. The head comes in a close 2nd. so all that said, I wish you luck on your project, I hope it holds up for as long as you need it to and maybe beyond. but if it doesn't, just remember things like this....