I am currently building a b18b with ITR pistons. I plastigaged the mains and I feel that they are out of spec. I would like to hear from experienced builders to confirm this.
The specs for 1,2,4,5 are .024-.042 service limit .050
journal 3 is .030-.048 service limit .060

Main Journal 1


Main Journal 2


Main Journal 3


Main Journal 4


Main Journal 5


Any feedback will be greatly appreciated

 

what are the measurements in " thousandths?

 

1 mm is approximately 0.039"

Basically, the .038 mm section is about .0015"

Why are you comparing them to what you want instead of showing us what you actually have?

Running the mains at 0.002" or 0.051 mm is not necessarily a bad thing.

 

for a race motor i wouldnt run anything less than .002 on the mains, i like to be closer .003 especially on the rods

for a street motor .002 is fine as long as you have plenty of oil psi

the spec for #3 calls for more clearance because the crank will flex in the center so you definately want to keep it no less than .002

i would say what you have looks good for a street motor assuming the plastiguage is accurate, .0015 on #s1,2,4,5 and .002 on #3

 

get the mains around .002 and the rods above .0018 in my opinion. higher power/revving motors i have seen first hand do not like rod bearing tolerances less than lets say .0016. i usually set my specs at the upper end of factory specs