Jkson 6/1 rebuild

[Gippslander]

The main bearing castings shold pilot on the crankcase bore. Measure the bore and the pilot on the bearing casting or simply place it on the crankcase by hand and check for movement. Should be a slip fit with very little movement.

OK . Yes I just tried what you have suggested .

The bearing casting moves up/down about .010"  in the bore of the crankcase .

I may have to use some steel shims around the circumference of the bearing castings ?

Thanks  Mike

[38ac]

"010 definitely falls into the iffy category for fit up and there is no easy fix. One of the of the  members had to move his crank centerline on one side to correct some shoddy machine work. Maybe he will chime in with what how he coped with the pilot hole. Quickly thinking about it I think I would be more inclined to place about 3 dowels in the casting but I wonder  about how loaded they will be and the casting breaking out around them?

[dieselgman]

Check measurements of both the case bore and also the housing pilot diameter... I can get you the measurements from good parts. Are both sides giving the same variance? You will have to be very careful about getting your crankshaft parallel with block deck such that piston travel is true inside the cylinder. Our usual method is to replace the offending parts. You should do the same if it is at all practical, rather than trying to shim or modify something that is very far out of spec.

dieselgman

[Gippslander]

Check measurements of both the case bore and also the housing pilot diameter... I can get you the measurements from good parts. Are both sides giving the same variance? You will have to be very careful about getting your crankshaft parallel with block deck such that piston travel is true inside the cylinder. Our usual method is to replace the offending parts. You should do the same if it is at all practical, rather than trying to shim or modify something that is very far out of spec.

dieselgman

that is good advice from 38 and dieselman

Would loctite hold the  casting in place in the bore ?

The other side has .005" of up/down play , it is not as bad as the .010"  

yes i may have to buy new castings , I can buy them from my supplier .

I do have a precision machinists level, maybe I can use it to check the crankshaft for being parallel with the deck

[32 coupe]

Have you put it together enough to know how many side gaskets you will
need to set the crank bearing preload and side play ?

That thing will jump around like crazy until you "get it all together".
Try shooting for the preload and crank centering and you may have
a different opinion on the up and down movemnt of the bearing carriers.

Gary

[Gippslander]

I measured the shoulder on the 2 castings , they both measure as 5.749"

The holes in the crankcase measure as 5.760"

I will buy a sheet of .005" shim stock and make a 1/4" wide shim to fit around the shoulder of the castings

Mike

[xyzer]

I measured the shoulder on the 2 castings , they both measure as 5.749"

The holes in the crankcase measure as 5.760"

I will buy a sheet of .005" shim stock and make a 1/4" wide shim to fit around the shoulder of the castings

Mike

Mike,
You may find it very difficult assembling the shim and casting. The math says it is possible but holding it in place while installing the housing may prove difficult. Final assembly with the crank in place will really make it a challenge! I would assemble it and paper shim the housings for the proper bearing load and check crank to deck alignment. You might use the extra clearance to your advantage in improving the alignment. Loctite makes a bearing bedding product you could use to provide some repeatability on assembly. A release agent may be required. Good Luck!

[32 coupe]

Mike,
How will you hold the shim stock in place ??

Read my post above. You will have those bearing holders
on and off several times setting bearing preload and crank
side to side setting to center the crank

One of my engines has sleeve bearings. When I tightened the bearing
carriers to torque specs the crank had a "tight spot" on one end. I had
to play with the torque on the bolts to get the crank to rotate where I
was happy with the "feel" while turning by hand. Different thing but it
gives you an idea of how "things change".

On your engine I would set the crank, play with end play then try to determine
if it was level with the top of the block. If the crank is not level you may try
to loosen the bearing carrier a little, tap the carrier to the correct spot and retighten
the carrier......

On yo

[32 coupe]

Sorry...
on your engine I would try this approach.  May save some time and headaches. ....

Just my 2 cents...



Gary

[dieselgman]

I just measured an original main bearing casting and also an Indian copy off our shelf on the pilot diameter - 5.749" for both of them... From that, it would appear that maybe your block was machined a bit too large in this area. I will have to measure up some blocks when I get the chance.

dieselgman

[Gippslander]

OK thanks to u all for the input .

The problem I have is:  the block has been machined with the bores too large 

I have used shims to fix problems like this before and I feel the .005" shims will work out OK 

I will post some pics of the fix ,  but right now I am still looking for gasket paper 

Mike

[32 coupe]

Mike,
I use shipping envelopes,  you know the brown or tan ones. They will be different
thicknesses.  Sometimes note book paper when needing something a little
thinner. Give a good wipe/soak with oil and you will be fine.

Here again, just my 2cents......

Gary

[32 coupe]

I will add this again.

IT WILL ALL CHANGE WHEN YOU BEGIN TO BOLT IT TOGETHER.


I would personally forego the "shims" for now.

Gary

[Gippslander]

I will add this again.

IT WILL ALL CHANGE WHEN YOU BEGIN TO BOLT IT TOGETHER.


I would personally forego the "shims" for now.

Gary

Ok Gary , the shipping envelopes. good idea 

I have decided to make new studs . I ran a 3/4" BSW tap through the deck threads, the Indian studs are very loose in the deck threads . The Indian studs are made from a soft mild steel , its crap .  I will buy some 3/4 good quaility tensile rod and thread each end of it .  Mike

[Gippslander]

I ran taps through the block and a lot of gunk came out