I am installing my scat crank into my block and I am using clevite 77 bearings. I measured the clearance and i got .003" on all of the mains. My question is in the chiltons manual it says that the clearance on #1 should be .001 - .0015 and .001 - .0025 on all the rest, but in the clevite application catalog it says that the clearances can be from .001-.0036. So which should i believe or are they both wrong and if so what are the correct clearances?

 

I had this same basic question a little while ago. I have the same bearings, and read the same specs, in Haynes and Clevite that you have. I have read numerous times that .0025"-.0028" is optimum, but you can go as high as .0035". Although, that large of a clearance is for 8000-9000rpm engines.

My point is that I SCRUBBED the bearings before I put them in. I'm used to getting metal shipments at work with a protective layer on them. I thought this about the Clevites. Well that "layer" is a soft, lead based coating on there to help trap metal shavings so that they don't tear up the bearing/crank journal. I washed that off and opened up my clearance to .0035" by doing so. Stupid me. So now I get to buy new ones. About $20. Could've been a more expensive mistake I guess. I remember that the #1 should be about the same to. As long as it isn't over .0025".

 

i'd try for .0015 to .0025 clearance i nthe mains. you can buy a set of +.001 OVERSIZE bearings and mix shells to get the clearance down a little. considering how cheap a set of bearings is it isn't a bad idea. are you checking clearance with plastigage? if you are i wouldn't consider it real accurate, not to .0005 anyway. best to check clearances with a dial gage, mikes, and snap gauges.

------------------
ICON Motorsports
1st & 3rd
MM Black Diamond 538 F&AM

 

ok i got some new bearings but was wondering how many times you can torque the main bolts? They are a new set of ARP bolts but i have already torqued them twice checking the clearances.

 

I wouldnt worry about the bolts, you havent run the engine yet so they havent seen any engine loading, and they havent seen any heat cycling yet either.