limige

ok, i decided to do a bit of work to the motor 1.5yrs ago when i blew my clutch. i wanted to put a cam in, p/p the heads, install headers, cleanup the intake, and put new rings and bearing in it. a real basic rebuild with some performance in mind.

ok, i pulled everything apart, mic'd the crank and it was nice a round on all the lobes but they were all turned under. it seems this motor was rebuilt just before i bought the car. i bought it with 72K on it and it now has 93K.

so the mains mic'd at 2.419, and the rod journels at 2.08

so the book calls for 2.4988-2.4998 on the mains, so i'm .080 under which means a set of .04 over bearings

the book calls for 2.0978-2.0998 on the rods, so i'm .02 under which means .01 over bearings right?

so when i goto install the new bearings i pulled out the old ones and on the back they were marked .03 on the mains and .02 on the rods!! wtf?

i put the new mains in and as soon as i snug up any single cap the crank does not want to turn. with the rods on and the main caps loose i can turn it over fine, but as soon as i snug a main she's tight.

i don't get it what's going on??? btw i plastigauged the mains they check out at .001-.0015. rods are another discussion all together. tighten to book specs and i'm way open like .003-.005, hard to tell with the wrong plastigauge. if i tighten them down to 60 ft#'s it reads more like .002 oil clearance.


so i don't get it, the crank seems great, just turned under, so anyone got a clue whats with the odd bearing sizes??

mike

limige

bump

limige

well, i pulled everything apart, pulled all the bearings, torqued the caps and measured the bores.

main bore measures 2.641-42
rod bore measures 2.226


so 2.641-2.419=.222
.222/2=.111 per side
.111-.001(oil clearance)=.110 bearing thickness.

my .04 over bearings measure .115
so whats going on here???

same with the rods
2.226-2.080=.146
.146/2=.073
.073-.001=.072
which comes out to a .02 over bearing.

so why don't the crank numbers match up with these sizes compared to the book? i figure the bores must have been changed but i don't have the numbers the bores should measure out to.


any thoughts??

limige

not that anyone seems to care but i figure out the problem.

my haynes manual has the wrong number for the main journels of the crank.
the correct number is 2.4488-2.4498

so my crank measures 2.419 which is .03 under the correct book size. therefor i need .03 over bearings,

being a machinist i wasn't sure if a .010 over bearing was .01 ground off the diameter or the radius. as it turns out it's the diameter.

so all my rod numbers where right i just didn't need to divide by 2 for the radius.
the only reason i thought otherwise was because my book had an incorrect number which measure .080 under, i know they don't make an .08 over bearing so i assumed you divide by 2 for a .04 over bearing.


so if anyone has a haynes manual know the numbers are wrong for the main journels. i'm going to see what i can do about getting them to cover the extra bearing set they cost me. lol like that's gonna happen.

you know for as many people that build engines on here i can't beleive nobody could help.

thanks alot guys....