Journal taper..how would that happen?

kopeck

Member
I've finally got my engine out of my '47 A. I was measuring up the journals and found one of my rod journals to be a little over .001 tapered. Plastigauge tipped me off and my mics confirmed it.

The weird thing is visually it looks perfect, like right out of the machine shop perfect. I really wonder how it ended up that way.

I'm going to bring it to the machine shop and see what they think. I was getting .003 to .004 of clearance but a couple of of the journals could use a polish so there might be a bit more clearance there then needs to be.

K
 
(quoted from post at 21:07:57 06/22/15) Isn't that within specifications ? I supose the stone was wore that much!

.003 is within factor spec, so one side of the journal is in spec the other side's a tad big...

K
 
I restored a Farmall A in 1975 that was in sad shape. The engine was a basket case and it needed tires, rims, steering wheel, seat, wiring and the engine was stuck and I installed a new sleeve kit. The crank was brownish looking and it measured .002" undersize. It only needed polishing and the machine shop furnished the new bearings. The tractor came with the 16-inch moldboard plow. I plowed my garden with it that Spring. I gave $100.00 for it. Hal
a194344.jpg
 
I'm hoping the crank is just in need of a polish.

The factor calls for .0015 - .003 of clearance but it doesn't really give a "it's all worn out spec". The engine made very good oil pressure before I tore it down.

Running .004 doesn't seem like the end of the world to me. The taper caught me off guard though, maybe it's not as big a deal as I think it is. Like I said I'm going to bring it into the shop and see what they think.

The original pistons are in really nice shape, the sleeves do show some wear but I think I'm going to run with them too. The ring gap is more then I was hoping for (.022 - .024) but probably still useable.

K
 
Does the taper start at one side and taper down or is it in just a
small area. do you know what rod and bearing came off the space. I
would mic the bearing and if the bearing is part of the rod I would
mic that bearing by using a depth mic.
 
Yes, the rods very definitely need to be professionally checked, both for straightness and "small end" and "big end" size.

A bent rod can cause the crank journal to wear to a taper.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top