.004" Thrust Clearance... Run it or tear it back down?

[af2]

In case some of you were thinking this : i'm not the op.

I think the lower half is to wide.

As I don't like smacking with a hammer to get the thrust set. I use a good size bar and put pressure on the crank going forward then tighten the rear main on a Chevy. Try that and re-measure with a feeler gauge.

[mike22l]

x2 what af2 said. Thats the way I do it also.

[robert1]

In between all other activities I mounted my crank and measured the thrust clearance.

With the number 5 cap not on the crank. I have .008. With the number 5 cap .003.

A little tight imo. What side would i need to sand and with which grit ?

thanks

I tried to outline this. Take a feeler gage and measure the clearance between the face of the bearing in the cap and the crank. It should measuure .008 as well if that's what you get without the cap. You can then proceed as follows.
1. You can blue each face of the bearing in the cap. pry the crank first forward and then aft as you rotate the crank. One face of the bearing is going to wear the bluing off. You can lap that face with 400 grit paper on a flat surface. When I'm describing this the bottom most part of the bearing is the part lowest when the motor is in operating position.
2. You can remove the dowel to free the cap movement to get more end play. If you remove the dowel make sure the hole isn't through to allow an oil leak. If the hole is through you can just drive the dowel down until it's flush with the block.
3. The face of the cap may not be square with block. Then you would only have to lap a small amount off of the bottom most part of the bearing to increase the clearance. You can verify this with a feeler gage. If it's tight on one side at the top and loose on the opposite side just lap the top of the tight side. When I'm refering to the bottom most part I'm talking about when the motor is in operating position.

[Belgian1979]

In between all other activities I mounted my crank and measured the thrust clearance.

With the number 5 cap not on the crank. I have .008. With the number 5 cap .003.

A little tight imo. What side would i need to sand and with which grit ?

thanks

I tried to outline this. Take a feeler gage and measure the clearance between the face of the bearing in the cap and the crank. It should measuure .008 as well if that's what you get without the cap. You can then proceed as follows.
1. You can blue each face of the bearing in the cap. pry the crank first forward and then aft as you rotate the crank. One face of the bearing is going to wear the bluing off. You can lap that face with 400 grit paper on a flat surface. When I'm describing this the bottom most part of the bearing is the part lowest when the motor is in operating position.
2. You can remove the dowel to free the cap movement to get more end play. If you remove the dowel make sure the hole isn't through to allow an oil leak. If the hole is through you can just drive the dowel down until it's flush with the block.
3. The face of the cap may not be square with block. Then you would only have to lap a small amount off of the bottom most part of the bearing to increase the clearance. You can verify this with a feeler gage. If it's tight on one side at the top and loose on the opposite side just lap the top of the tight side. When I'm refering to the bottom most part I'm talking about when the motor is in operating position.

Thanks for this advice Robert.

Currently I have wacked the snout and rear of the crank with a rubber mallet several times. After some tries I seem to get .005 when prying to the rear and front and measuring with a dial on the snout.

I have a couple of rods and pistons on it now to check for Ptv and pth clearance. Will redo the check with the bluing. I have to mention the block is a 86 up block and doesn't seem to have a dowel in it.

Another question to this : would making a chamfer on the bearing parting line help oiling to the trust bearing ? If so, do you make the chamfer from the oil groove towards the rear or to the front ?

[robert1]

You could groove to the rear. Might help wont hurt. I have some coated bearings that haven't been used yet that have the thrust face flaking. I'm not sure extra oil helps I think it may be just bad electro plating when they make the bearings. Of course they will always tell you you are the only one that has ever had a problem. Take a file and make a 45° chamfer on the upper bearing from the groove towards the rear face at the parting line. One side should be plenty.