Mixing Bearings... Safe?
12-30-2005, 07:11 PM
#1
Mixing Bearings... Safe? I just got a call from the engine builder who I was having balance the rotating assembly and checking the bearings clearances. They said that they had to mix and match standard and 1-under bearings to get the clearances right. They said that with the standards, the clearances were about .003 on all the mains and the rods(thank you Eagle
). Wouldn't it make sense just to use the entire set of 1-unders besides mixing and matching them?... I told them to use the whole set and they said they would... I guess not. Also, they are probably mixing brand too because I have no idea what brand bearings were in the block already, and I think they put in Clevites. So is it safe to mix brand and size bearings? Thanks
). Wouldn't it make sense just to use the entire set of 1-unders besides mixing and matching them?... I told them to use the whole set and they said they would... I guess not. Also, they are probably mixing brand too because I have no idea what brand bearings were in the block already, and I think they put in Clevites. So is it safe to mix brand and size bearings? Thanks 
12-30-2005, 07:21 PM
#2
Yes it is safe and done to get clearances close. Sometimes clearances are such that the next full size up or down is too much and mixing them allows builders to get closer to "just right". It would cost a lot more to grind the crank or resize the rod big ends.
12-30-2005, 09:55 PM
#4
Ok, just making sure. It looks like there were Clevite standard sized race bearing in the block already, and then they mixed with Clevite 1-under race bearings. Looks like they only had to mix on the #2 main. Heres what they ended up with...
Main #1: .0017 (Both 1-unders)
Main #2: .0018 (Upper standard, Lower 1-under)
Main #3: .002 (Both standard)
Main #4: .0017 (Both 1-unders)
Main #5: .0019 (Both 1-unders)
Rods: .0018 (All bearings are Clevite race 1-unders, no mixing)
These clearances looks very nice to me. Should have good oil pressure and long life. I am pretty happy with the shop's job on this, although it was VERY pricey.
EDIT: The standard sized bearings are actualy Federal Mogul, instead of Clevite. They have a 'F/m' stamped in them, while all of the Clevites have 'CLEVITE' stamped in them. So my mains have three Federal Mogul bearings, and seven Clevite bearings. Only one main has both FM and Clevite bearings. I assume this is okay? However, the oil races in the Clevite and FM bearings are different. The FM oil races stop at about 8:00 and 4:00, while the Clevite races stop at about 10:00 and 2:00. So with the FM upper bearing and Clevite lower bearing the oil races are coming to a SUDDEN stop at 9:00 and 3:00 instead of a smooth and gradual stop. How will this affect the oiling on the #2 main? I will take some pictures to better explain.
Main #1: .0017 (Both 1-unders)
Main #2: .0018 (Upper standard, Lower 1-under)
Main #3: .002 (Both standard)
Main #4: .0017 (Both 1-unders)
Main #5: .0019 (Both 1-unders)
Rods: .0018 (All bearings are Clevite race 1-unders, no mixing)
These clearances looks very nice to me. Should have good oil pressure and long life. I am pretty happy with the shop's job on this, although it was VERY pricey.
EDIT: The standard sized bearings are actualy Federal Mogul, instead of Clevite. They have a 'F/m' stamped in them, while all of the Clevites have 'CLEVITE' stamped in them. So my mains have three Federal Mogul bearings, and seven Clevite bearings. Only one main has both FM and Clevite bearings. I assume this is okay? However, the oil races in the Clevite and FM bearings are different. The FM oil races stop at about 8:00 and 4:00, while the Clevite races stop at about 10:00 and 2:00. So with the FM upper bearing and Clevite lower bearing the oil races are coming to a SUDDEN stop at 9:00 and 3:00 instead of a smooth and gradual stop. How will this affect the oiling on the #2 main? I will take some pictures to better explain.
Last edited by Ferocity02; 12-30-2005 at 11:42 PM.
12-31-2005, 12:08 AM
#5
Here are some pics of what I am talking about...
Federal Mogul bearing, oil races stop at 4:00 and 8:00
Clevite bearing, oil races stop at 2:00 and 10:00, no oil race on bottom half
Federal Mogul & Cleavite bearings, oil races suddenly stop at 3:00 and 9:00
Federal Mogul bearing, oil races stop at 4:00 and 8:00
Clevite bearing, oil races stop at 2:00 and 10:00, no oil race on bottom half
Federal Mogul & Cleavite bearings, oil races suddenly stop at 3:00 and 9:00
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01-01-2006, 12:13 AM
#9
****. I guess I will try to find a single Clevite standard upper main bearing half, or buy a whole set and change the thrust bearings also to Clevite. Here is another question. If I replace the FM STD bearing half with a Clevite STD bearing half will the clearance be about the same, or will it need to be rechecked? Thanks!
