VTEC_Du_Ma_Mai

So I'm building an ls vtec and came across some issues and thoughts:

1. My rod and crank bearing codes are 3B all across which gives me a Green OEM bearing. I measured the rod journals and they are all 1.7712" +/-0.0001". I have not measured the rod bore. Now if you calculate the oil clearance using my rod journal diameter, green bearings(0.0590"x2), and factory rod bore(1.890"), you get 0.0008" oil clearance which is the tight end of factory B18a/b specs. Even when using the whole range of stock journal diameters(1.7707"-1.7717"), you get an oil clearance range of 0.0003"-0.0013" that barely gets into the B18c range. So my question is, are ls cranks and gsr cranks sized differently? As in, a "B" journal on an ls crank is not the same size as a "B" journal on a gsr crank. Am I on to something or am I totally off base?

2. Assuming I'm on to something in part 1, maybe one of the reasons so many people spin bearings on ls-vtec setups is because they go by the coding system and just drop in the correct bearings without checking oil clearances, whether by mic and dial bore or plasti-gauge. Because the correct bearings for an ls crankshaft will put you into the correct oil clearance range of 0.0008"-0.0015" which is pretty tight for a higher revving motor which requires an oil clearance of 0.0013"-0.0020".

Please let me know what you think and if I missed anything. Thanks.

VTEC_Du_Ma_Mai

Either nobody knows what I'm talking about or I stated something pretty obvious. So I guess I just want to help the beginner lsvtec builders by saying: Do not use the coding system to finalize your bearing choices. Use measurements from a micrometer and dial bore gauge and/or plasti-gauge. Because I'm pretty confident that the majority of the time you will need thinner bearings than what the codes tell you to get in order to achieve your desired oil clearance.