Bearing Clearance Questions
11-06-2016, 07:06 PM
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Bearing Clearance Questions
Yesterday I received back my crank, block, head, and timing cover from the machine shop. I had some questions as I was reassembling:
Using some Plastigauge I just purchased, I measured .002 inches between the bearings and the crank. My book lists this as almost out of spec (spec listed as .0010 to .0022 inches), should I just ignore it and keep going? I am installing all new bearings from LC Engineering.
Second, I can see some movement in my thrust bearings/washers when I rotate the crank back and forth. Should I be worried about that? The thrust bearings/washers on the block side slide back and forth a decent amount, and I was wondering if that was normal. I attempted to follow the correct procedures from the book (torque to spec [40-47 ft-lb] all caps except center, pry back and forth, hold forwards, torque center to spec) but the crank didn't seem to move any noticeable amount. Now that everything is torqued, the crank does move just a little forwards to rear, but only a very small amount.
With everything lubricated with some engine assembly lube, I can spin everything with just my hand. It turns fairly easily, just feels a bit sluggish. I'm going to guess that is from the assembly lube, since there is no audible grinding or anything.
Using some Plastigauge I just purchased, I measured .002 inches between the bearings and the crank. My book lists this as almost out of spec (spec listed as .0010 to .0022 inches), should I just ignore it and keep going? I am installing all new bearings from LC Engineering.
Second, I can see some movement in my thrust bearings/washers when I rotate the crank back and forth. Should I be worried about that? The thrust bearings/washers on the block side slide back and forth a decent amount, and I was wondering if that was normal. I attempted to follow the correct procedures from the book (torque to spec [40-47 ft-lb] all caps except center, pry back and forth, hold forwards, torque center to spec) but the crank didn't seem to move any noticeable amount. Now that everything is torqued, the crank does move just a little forwards to rear, but only a very small amount.
With everything lubricated with some engine assembly lube, I can spin everything with just my hand. It turns fairly easily, just feels a bit sluggish. I'm going to guess that is from the assembly lube, since there is no audible grinding or anything.
11-06-2016, 07:50 PM
#2
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A factory new engine is made as absolutely tight as is possible in mass production.
This is why they often run 300,000 miles the first time around.
Your .002 clearance is plenty tight, don't worry.
Maybe your rebuild will only last 200,000 miles.
It is very likely that the crank endplay is good as well.
The best way to tell is with a dial indicator on one of the crank cheeks and levering the crank back and forth with a large screwdriver, or bar.
Short of this, you could lever the crank one way and use feeler gauges on the loose side of the thrust bearing to get a good idea of endplay.
In service, the crank only turns one direction, and the thrust washers will be pushed to their stop and stay there.
The crank should still turn fairly easily after the main caps are torqued, if it does'nt somethings' not right.
It'll get harder to turn after the pistons are in, and it will take a rachet, or breaker bar on the crank snout to turn it then.
I'm sure that you will plastigauge the rod clearance too. You'll likely find it to be near upper spec also.
Good luck with your rebuild, I'm sure you are doing just fine.
This is why they often run 300,000 miles the first time around.
Your .002 clearance is plenty tight, don't worry.
Maybe your rebuild will only last 200,000 miles.
It is very likely that the crank endplay is good as well.
The best way to tell is with a dial indicator on one of the crank cheeks and levering the crank back and forth with a large screwdriver, or bar.
Short of this, you could lever the crank one way and use feeler gauges on the loose side of the thrust bearing to get a good idea of endplay.
In service, the crank only turns one direction, and the thrust washers will be pushed to their stop and stay there.
The crank should still turn fairly easily after the main caps are torqued, if it does'nt somethings' not right.
It'll get harder to turn after the pistons are in, and it will take a rachet, or breaker bar on the crank snout to turn it then.
I'm sure that you will plastigauge the rod clearance too. You'll likely find it to be near upper spec also.
Good luck with your rebuild, I'm sure you are doing just fine.
11-06-2016, 08:15 PM
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Thanks!
I wasn't sure if it was OK or not. Don't want to put it back together just to have it blow up after 5 minutes.
The crank does turn fairly easy, it just takes one hand. It feels sluggish, but that is probably the engine assembly lube creating drag, as it rotates smoothly. Doesn't seem to be sticking or grinding at all.
I'll probably end up putting the pistons in tomorrow.
I wasn't sure if it was OK or not. Don't want to put it back together just to have it blow up after 5 minutes.
The crank does turn fairly easy, it just takes one hand. It feels sluggish, but that is probably the engine assembly lube creating drag, as it rotates smoothly. Doesn't seem to be sticking or grinding at all.
I'll probably end up putting the pistons in tomorrow.
