4age 100kw rebuild - main bearing clearance

[Grega]

Hi

for those more educated than i am (with practical knowledge if possible), i'm rebuilding my 100kw motor.

i had my crank ground 10 thou on the mains and big ends as they were no good and the crank had the slightest 'bend' in it. the rod ends were resized and with the new bearing shells come in perfectly all at 0.051mm. lovely

my mains are another story, with the new 10thou shells,

1,2,4,5 are all 0.076mm
3 is 0.051mm

my book tells me the following

U/S 0.25mm (10thou) 0.013mm - 0.053mm should be the standard oil clearance
max oil clearance is 0.10mm, so at 0.076 i'm in tolerance.

remembering that 3 also has duties of thrust it has less clearance than 1,2,4 and 5

would this pose me any problems and is this acceptable given i'm within tolerances. for the life of me i can't find my other clearances when i built my last sweety 4age

comments/flames/thoughts all listened to.

[fixeruperer]

have you measured the crank or swaped bearings around ?
if its within tolerance it should be fine, but it would be nice to find out why its out. (you do get the odd one out everynow and then) if you cant find a prob, measure the crank maybe you can play with that.

[Grega]

no - that i havent done.
its well within tolerance so theres no issue, but, that #3 main with the 0.051 is interesting.
the only thing i'm thinking is that the #3 tunnel is possibly a little tight over 1,2,4,5 - it wasn't resized (my rods were and they are absolutely perfect)
waiting to speak to machinist.

[fixeruperer]

ahh k, i thiught you had it tunneled aswell. well measure them up and see what you get.
i usually do it all when i build a problem engine (like your bent crank) re-size rods, tunnel bore mains and measue/grind/linish crank.