Babbit clearancing
 

I have my engine out right now and wanted to check clearances while out. Following the book setting clearances to .001-.015 at 50ftlb on the mains and 35ftlb on the rods.

When I torque the crank to the full 80ftlb or any one of the rods, it locks up. So judging by that I need to be looser than the spec in the book in order for the engine to turn? Anybody dealt with this situation?

I guess I need buy new shim packs and start all over? Feeling like I never should have touched it.

Re: Babbit clearancing
 

Go one at a time and find out which bearing is locking and then work it with needed shim or shims.

Re: Babbit clearancing
 

I went by the same guidelines and my engine did the same thing. I checked with a local A engine builder and he said when he sets the clearances he torques it down to the 80lbs instead of the 50. I tried that and mine did fine.

Re: Babbit clearancing
 

Brass shims may compress some but not so much that it locks up. The old steel ones won't. If only one is locking up the that will make life easier. If more then not so much. It shouldn't lock up if shimmed for proper clearance. Shims can be too thick so it can be a PITA to get clearances to specs if that's the case.

Re: Babbit clearancing
 

I went one bearing at a time full torque, removing the thinnest shim one at a time, until crank locked, then added one shim back. (Also need to verify shim pack thickness on each side of bearing, in case of different thickness remove from the thick side.) Also I torqued the adjacent bearing/s to 50ftlbs to ensure crank alignment and bearing even loading, but not effect the crank lockup. Did pretty much same on rods at lower torque settings, but no worry on the alignment issue as with the crank. Worked excellent. But time consuming, plus my engine is in my car, rear main was tough, just don't drop anything into the bell housing. Good luck, anything worth doing, is worth doing the best you can. I hate looking back and thinking I didn't do my best.

Re: Babbit clearancing
 

So to put this in perspective, 50ft# tork should net approx 9500 # clamping force and 80ft# 12500 #clamping force.
If the clearances do not remain constant that would indicate movement /distortion causing the binding.
It could be the caps or the shims are compressing, you just have to test each one.

Typically, 1/2-20 (GR 8) bolts max tork at 80-90ft# lubed before yielding.

John

Re: Babbit clearancing
 

Start over with new shim packs removing one pair at a time. Go to full torque. I use 35 and 75. When it locks up put one shim back in, torque again, if it still has drag, put the other shim in. Time and patience you will get the job done. Do the mains first. It is never easier than when it is out and upside down.

Re: Babbit clearancing
 

Amen!

If that was my block and... i had it out and upside down (lol) i would start with stock specs. and with some plastigauge in each bearing. I would just clamp load to spec everything. then see who is too tight or too loose. then adjust accordingly. My thots are not novel....

I see the subject has come up before on the Ford Barn.

thread title: Platigage and bearing clearances

Re: Babbit clearancing
 

Why are you torquing the rods and mains to 80lbs? That’s too high for both and double what they should be for the rods.

Also, why are you setting the clearance at one torque setting and then finishing at a different torque?

Re: Babbit clearancing
 

OP:"When I torque the crank to the full 80ftlb or any one of the rods, it locks up."

It sure reads that way! But... i tend to think he means the mains at 80 and (implied) the rods at 35. ;)

besides, rods prob would strip at 80 ft #s!!! :eek:

Re: Babbit clearancing
 

Too add, be careful on the center main cap. That bearing tends to wear more. If it is in fact worn more, say on the bottom half, then the crank may try to bend during torque up. You have to consider this or it will be problematic to get it where it will still function. It can be tricky to get old worn journals adjusted to working specs. Sometimes it just doesn't work out well. Folks used to lap the caps to get the journal back straight or somewhere close but this tends to be self defeating over time when a person goes to overhaul & repour the bearings. Aligning the mains with new babbitt is the best way to eliminate this kind of problem.

Re: Babbit clearancing
 

Another answer is to use the yellow Timesaver to bed in the offending bearing. The yellow Timesaver will remove material from soft metal but not the crankshaft. Bring the torque up a little at a time while using the yellow Timesaver and turning the crankshaft over. When done, clean out all the Timesaver.

Re: Babbit clearancing
 

Idkwibp

Re: Babbit clearancing
 

my stocker engine had a low rpm, high load growl... that only spelled one thing! bad main! yup! looked into it some of it gone, some of it barely tinfoil. now has a new bottom cap. Prussion blue and a scraper... later than sooner, i had it close enuff to try. :confused: sounded much better. it was me that was upside down and under, but not out!

https://fonts.gstatic.com/s/e/notoem....0/2615/32.png

Re: Babbit clearancing
 

That's the way I was taught to set/check clearances.

Re: Babbit clearancing
 

That's probably what I'll do. Start again with new shims and go at full torque.

Yeah I almost think I could do it by feel better than with the plastigauge.

80 and 35. I'm doing the process described in Les Andrew's book.

Interesting that you say that. I also have a similar growl and found my rear main has failed. Although I don't have the time or money to rebuild right now I was going to stick it back together and run it a while longer.

https://i.imgur.com/0pzCRkd.jpeg

Re: Babbit clearancing
 

IMO, .001" is too tight. I'm a racer and set all my clearances at .002" minimum. Too loose is better than too tight!

Re: Babbit clearancing
 

I am never going to work on bearings from under a vehicle again.And I have a lift to make it easier too.Upside down,looking down.I rolled bearings into Caterpillar,Cummins,Mack,and Detroit engines laying on my back for over 40 years.Never going to fight the oil dripping into my face again.I've always felt that that 64 pound flywheel hanging on the rear throws the rear main adjustment off.I've had the best luck using the tin foil method.Just check every piece before you put it under the cap.They are pretty much .001 thick,but have found some old american made foil to be a little thicker.Dollar store store foil works just fine.

Re: Babbit clearancing
 

There are thousands of cars running around with bearings that are too loose - there are NO cars out there with bearing too tight.

Re: Babbit clearancing
 

My method as well. Foil here is 0.0005" thick so I use three layers by cutting a 1/2" x 1 1/2" piece and folding it over to get 3 layers 1/2" x 1/2".