Thread: Crankshaft prep
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Old 10-08-17, 07:01PM   #8
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Join Date: Mar 2008
Location: Pittsfield NH
Posts: 632

Have my Scat custom crankshaft form they requested I fill out since I'm paying for a forged 4.0 stroke 400 crank with a custom rod journal. The rod journal is being downsized and offset to increase stroke with a -.020 BBC rod journal size . The diameter of the rod journal I spec'd @ 2.179" for a clearance of .0023-.0025 with the rod bearings that have already been calico'd and professionally measured. I had also spec'd an offset of plus .010 for a stroke of 4.020 as I thought thats all that would be available from a 2.20 rod journal and I wanted strong even fillets. My block has been decked and measured to 10.220.

Scat told me after putting down my deposit they only had a raw forging so I asked them if I might be able to get the additional .010 I had wanted for a 4.040 stroke and zero deck height with my 6.900 rod and 1.300ch piston. They said "maybe" and sent me this form. It specifically asks for rod width and journal width I had professionally measured, rods are .994 so desired journal width of 2.008-2.010 for a .020-.022 side clearance was advised. Im using CB-743HN -.020 rod bearings (FM 113M-std mains).

Was curious about thrust dimension they will grind in and wondered if anyone here might have gotten a Scat crank and measured it and know what they typically run and whether that works well or not? I have the opportunity to have them grind that to my spec since its a raw casting. Possibly make other small beneficial changes too? Thanks for any input ... will be sending form shortly.
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