[mrennie]

Hello,

After getting good main bearing oil clearance I checked the thrust bearing clearance and it is toooooo tight...I am getting .0015".

I removed the cap and checked with just the upper (block) bearing shell and got just under .007" end play.

So I pulled out the crank, then reinstalled the cap and bearing, and put a straight edge across the bearing shells near the parting line and saw light on one side indicating a gap. If I put the straightedge on the other side I also see a small gap except it is on the other bearing shell.

I was thinking that maybe the bearing cap might have been misaligned (and I was hoping it wasn't since the block was line bored), and with just the cap installed (no bearing) I could not detect any step or misalignment between the block and cap.

To confirm this I installed the cap and just 1 bearing shell, and after torquing the cap I could easily rotate the single shell around the bore so it does not appear that the cap in misaligned.

I then started checking the bearing shells and have found that the thickness of the thrust flange changes from from one end to the other, by about .0025". This seems to be consistent across both the upper and lower shells, in the same direction, and when you install them it results in a "step" difference at the parting line of around .005" which I have confirmed with a straight edge and feeler gauges.

How come nothing is ever simple for me!!!!!!

I checked a different model bearing (but same manufacturer) and get close to the same variation/step. A different brand of bearing (but which has too little oil clearance so I cannot use them) only has a variation of .0015" from one end to the other when I measure them so I am not seeing things.

Anyone seen this before? Is there anything I can do to fix this?

I have read about sanding the thrust surface to increase thrust clearance, but if I correct both sides I am sure I will end up with more than .009" clearance.

I suppose the rear is the really important side so I am hoping to sort this out.

My initial thought is to slide the the upper/lower bearing shells onto the cap so the parting line is at the 12 o'clock position, then sand the rear side with 800 grit on a surface plate until the ends are closer to the same thickness, then remove and reinsert so I am working of the opposite parting line area of the rear side.

Does this make sense or I am out to lunch?

Any advice is appreciated.

Thanks

Michael

[Formulas]

Try installing the crank leave thrust cap loose tap or pry crank front to rear then tighten the thrust cap and check play

[gtofreek]

Now you are starting to understand what we engine builders go through on a daily basis. This is no problem. There is almost always a difference in thickness in the flanges. Concentrate only on the rear flanges. Take the thinnest rear flange and mike it all the way around. You will find even the same flange will vary in thickness as you check around it.

I hold the bearing in my hand with my fingers pressing down on the flange and hold it flat on your surface plate. Now, using your fingers to apply more pressure to the areas that are thicker, you can sand in circular motions until the flange is equal thickness all the way around. You shouldn't have to remove more than .0005"-.001" from the thinnest area. Now that you have the thinnest flange equal, you now need to just make the rear flange of the other bearing the same thickness.

I just lightly sand the front flanges just to clean them up. If they are not the same thickness, don't worry about it. Making them equal will only increase thrust clearance. The rear is what needs to be lined up good so each half can absorb the pressure. You can use 220 grit to rough them in then follow up with the 800 grit to smooth them out. Some fine scratch's on the surface are good for holding oil.

After you have the flanges equal, put the crank in and torque down the other 4 main caps but just lightly snug the bolts on #4. Maybe 20 ft. lbs. Then, like Formulas mentioned, hit the front of the crank snout with a big rubber mallet, then hit the rear crank flange hard enough to knock the crank into the thrust bearing and shove it evenly against each half. This is much more critical on other engines since they don't have dowel pins to locate the main cap, but I still do it on these as it can move a minute amount. Now I use a prybar or big screwdriver to jam in between one of the other main caps and crank counterweight, to hold the crank snugly forward against the rear flange of the thrust bearing, and torque the bolts down.

Now, rather than check the crank thrust play with a dial indicator on the front snout, use a feeler gauge and check the rear side of the thrust bearing for clearance. Check each half of the thrust bearing to be sure they are equal. Check all the way around because sometimes they can be crooked, causing the clearance to be tighter on one side of the block. If you just use a dial indicator, you will have no idea if the flanges are equally clearanced.

[mrennie]

Originally Posted by Formulas

Try installing the crank leave thrust cap loose tap or pry crank front to rear then tighten the thrust cap and check play

I had done that, but it did not result in any extra clearance. It wasn't until I removed the cap and got extra clearance that I knew I was in for some fun.

[mrennie]

Originally Posted by gtofreek

Now you are starting to understand what we engine builders go through on a daily basis. This is no problem. There is almost always a difference in thickness in the flanges. Concentrate only on the rear flanges. Take the thinnest rear flange and mike it all the way around. You will find even the same flange will vary in thickness as you check around it.

I hold the bearing in my hand with my fingers pressing down on the flange and hold it flat on your surface plate. Now, using your fingers to apply more pressure to the areas that are thicker, you can sand in circular motions until the flange is equal thickness all the way around. You shouldn't have to remove more than .0005"-.001" from the thinnest area. Now that you have the thinnest flange equal, you now need to just make the rear flange of the other bearing the same thickness.

I just lightly sand the front flanges just to clean them up. If they are not the same thickness, don't worry about it. Making them equal will only increase thrust clearance. The rear is what needs to be lined up good so each half can absorb the pressure. You can use 220 grit to rough them in then follow up with the 800 grit to smooth them out. Some fine scratch's on the surface are good for holding oil.

After you have the flanges equal, put the crank in and torque down the other 4 main caps but just lightly snug the bolts on #4. Maybe 20 ft. lbs. Then, like Formulas mentioned, hit the front of the crank snout with a big rubber mallet, then hit the rear crank flange hard enough to knock the crank into the thrust bearing and shove it evenly against each half. This is much more critical on other engines since they don't have dowel pins to locate the main cap, but I still do it on these as it can move a minute amount. Now I use a prybar or big screwdriver to jam in between one of the other main caps and crank counterweight, to hold the crank snugly forward against the rear flange of the thrust bearing, and torque the bolts down.

Now, rather than check the crank thrust play with a dial indicator on the front snout, use a feeler gauge and check the rear side of the thrust bearing for clearance. Check each half of the thrust bearing to be sure they are equal. Check all the way around because sometimes they can be crooked, causing the clearance to be tighter on one side of the block. If you just use a dial indicator, you will have no idea if the flanges are equally clearanced.

Hi Paul,

THANK YOU VERY MUCH!!

That is exactly what I needed know, and it confirms I am not going crazy. I'll work in this today and report back how I make out.

I really do appreciate that pro engine builders have to watch for a lot of things to ensure a successful engine build, and I thank you for sharing your knowledge.

[mrennie]

Paul,

You were on the money about the thrust thickness varying across the face of each shell.

One shell varied by .0015 and the other by .0025.

First I sanded the one that was the thinnest (which was also the one that varied .0015") until it was flat within .0005". This shell ended up about .0005" less than the thinnest reading when I started.

I then sanded the other shell (which was thicker) until it was flat (removing the .0025" variation), but did not sand it to match the thinner one as I wanted to check their fit first.

After installing in the block (smacked crank with a deadblow hammer from front, then rear, then tightened cap with prybar pressure applied from rear) I got end play of .004-.005". Checking with feeler gauges, I had .004" gap between the thicker shell and the crank, and .008" between the thinner shell and the crank.

I then removed the thicker bearing, and sanded it down to match the thinner bearing, and it is flat within .0005".

I checked end play with a dial indicator, and I am getting .0085". When I check with feeler gauges I feel slight drag with a .008" feeler on one shell ( a .009 is snug) and can't quite fit it in the other shell (a .007" fits OK).

I marked the rear thrust surface with red marker and see contact on about 30% of the shell with the .007" gap, and no contact on the other shell.

Any advice here? I am hesitant to try and take the last .0005"-.001 off the thicker shell as it appears I will end up over .009" for end play.

Thanks again!

Michael

[LPI]

Michael,

What are you using for main caps and fasteners? Also did you put a 45 degree notch (old Pdude trick) on the four mating corners of the thrust bearing flanges?

I have seen quite a few that have an interference fit.

[gtofreek]

I would rather have .009" on both halves than one half take all the force. I would sand it to match. You would even be fine at .010". Some 326's call for .012" from the factory.

Originally Posted by mrennie

Paul,

You were on the money about the thrust thickness varying across the face of each shell.

One shell varied by .0015 and the other by .0025.

First I sanded the one that was the thinnest (which was also the one that varied .0015") until it was flat within .0005". This shell ended up about .0005" less than the thinnest reading when I started.

I then sanded the other shell (which was thicker) until it was flat (removing the .0025" variation), but did not sand it to match the thinner one as I wanted to check their fit first.

After installing in the block (smacked crank with a deadblow hammer from front, then rear, then tightened cap with prybar pressure applied from rear) I got end play of .004-.005". Checking with feeler gauges, I had .004" gap between the thicker shell and the crank, and .008" between the thinner shell and the crank.

I then removed the thicker bearing, and sanded it down to match the thinner bearing, and it is flat within .0005".

I checked end play with a dial indicator, and I am getting .0085". When I check with feeler gauges I feel slight drag with a .008" feeler on one shell ( a .009 is snug) and can't quite fit it in the other shell (a .007" fits OK).

I marked the rear thrust surface with red marker and see contact on about 30% of the shell with the .007" gap, and no contact on the other shell.

Any advice here? I am hesitant to try and take the last .0005"-.001 off the thicker shell as it appears I will end up over .009" for end play.

Thanks again!

Michael

[mrennie]

10-4, I'll work on it some more and see what I get.

Thanks