Tighten .010 main bearing clearances.
- Thread starter czimpel
- Start date
i too trust my bore gauge AND my micrometer i can't believe some of these answers there is a +/- .0005" tolerance for the bore get outside that and you just might get into big trouble not having proper bearing crush to hold it or too much to deform it the answer here is simple and every high performance engine shop does it on a regular basis if you want the clearances on the low side have the bore honed to the low side of the spec ( of course you have to take the variation of the crank into consideration as well) then measure bearing shells and sort them by thickness if you measure several sets of .010 bearings you will find that they range from .0979 to .0984 and it doesn't matter what brand of bearings you measure they vary from production run and from box to box and even within a single box---------that variation will give you a range of +/- .001 and everywhere in between in steps of .0001 depending on how you mix and match them and you will still be using .010 bearings sometimes it can take me a couple hours to fit just the four mains and twice that long to do the rods I have cabinets with drawers that are filled with hundreds of bearing shells marked STD, .0008, .001, .010, .020 i know a friend who once had a job in a NASCAR engine shop and his job all day long was to just sit and mic bearing shells and sort them by size when people bring me an engine to build i tell them in advance that the chances that the bearings they bring me will end up in their engine is very slim they will most likely end up in my bearing cabinet in place of the bearings that were the correct fit for their engine------personally i tend to set my mains between .0018 and .0022 but everyone has their preference but if you think you are going to just take a box of bearings and drop them in and they are going to be even close to correct you better have one really skilled crank grinder with a lot of patience......................RCI agree. I trust my bore gauge!!!
for those that havent taken the time to examine the range that you can expect from bearings here is some useful information
mains marked STD range from .0929 to .0936
.001 range from .0935 to .0940
.010 range from .0979 to .0984
.020 range from .1032 to .1036
rod brgs marked STD range from .0612 to .0616
.001 range from .0618 to .0621
.010 range from .0663 to .0669
.020 range from .0714 to .0717
please note that these measurements are at the center of each half shell and that the ends of the bearings are quite a bit thinner than they are in the center
mains marked STD range from .0929 to .0936
.001 range from .0935 to .0940
.010 range from .0979 to .0984
.020 range from .1032 to .1036
rod brgs marked STD range from .0612 to .0616
.001 range from .0618 to .0621
.010 range from .0663 to .0669
.020 range from .0714 to .0717
please note that these measurements are at the center of each half shell and that the ends of the bearings are quite a bit thinner than they are in the center
Phoneguy
Cometic HG stress tester
- Joined
- Aug 27, 2002
When we built my engine at Richard Clark's shop , he opened at least 6 sets of rod bearings to get my clearances perfect! Richard is as anal as they come when measuring! His measurements are an art...
Hoping for a 9 second time slip in BG. If I get it , it will be his 3rd 9 second 109 that he built. I am hoping to do him proud. Thanks Richard !!!!
Bryan
Hoping for a 9 second time slip in BG. If I get it , it will be his 3rd 9 second 109 that he built. I am hoping to do him proud. Thanks Richard !!!!
Bryan
Nice ! Good luck with your killer !
