alright guys , im pretty confused at the moment about what does runout and taper mean ? are they the same thing ???
i'm trying to find out how much runout can my main journals on sbc eagle crankshaft have.
on a book that i have they say that GM allows up to 0.007" runout but a competition engine should have no more then 0.001"runout...
my engine is a 383 with about 350 hp. and i got a 0.002" runout on my main journals,
is that good to go for me????

thanks , Ron

No more than .001

with the crank laying in the block with only a front and rear main bearing in place,, spin the crank by hand with a dial indicater on the center main to check runout.

mic the journals from front of the crank to the rear of the crank in at least 4 places arround the journal. a change from front of the crank to the rear of the crank on each journal is measuring taper. remember each rod pin has 2 journal spots,, so to speak.

what's your bearing clearance showing? how fast are you going to spin it? larger bearing clearances can tolerate a tad bit more runout.
andy

with the crank laying in the block with only a front and rear main bearing in place,, spin the crank by hand with a dial indicater on the center main to check runout.

mic the journals from front of the crank to the rear of the crank in at least 4 places arround the journal. a change from front of the crank to the rear of the crank on each journal is measuring taper. remember each rod pin has 2 journal spots,, so to speak.

what's your bearing clearance showing? how fast are you going to spin it? larger bearing clearances can tolerate a tad bit more runout.
andy
alright i got it now, (taper / runout)
yeah, so i did the runout check and like i said i've got a 0.002" runout
my bearing clearence is 0.003" to 0.0035"..
this engine ain't going to see no more then 5.500 rpm

alright i got it now, (taper / runout)
yeah, so i did the runout check and like i said i've got a 0.002" runout
my bearing clearence is 0.003" to 0.0035"..
this engine ain't going to see no more then 5.500 rpm

so,, your runout is .002,,,, so with it less than your bearing clearance,, i'd run it.
andy

so,, your runout is .002,,,, so with it less than your bearing clearance,, i'd run it.
andy
alright ,thanks

your welcome.
andy

alright guys , im pretty confused at the moment about what does runout and taper mean ? are they the same thing ???
i'm trying to find out how much runout can my main journals on sbc eagle crankshaft have.
on a book that i have they say that GM allows up to 0.007" runout but a competition engine should have no more then 0.001"runout...
my engine is a 383 with about 350 hp. and i got a 0.002" runout on my main journals,
is that good to go for me????

thanks , Ron

Does the crank spin freely when it is installed in the correct clearance bearings lubricated with lubriplate and the mains torqued to spec?

If so you are golden.

alright i got it now, (taper / runout)
yeah, so i did the runout check and like i said i've got a 0.002" runout
my bearing clearence is 0.003" to 0.0035"..
this engine ain't going to see no more then 5.500 rpm

With .002 TIR thats only .001 off center it should be fine to run.

Does the crank spin freely when it is installed in the correct clearance bearings lubricated with lubriplate and the mains torqued to spec?

If so you are golden.
yes,thats what i did right after the runout test...
thanks

With .002 TIR thats only .001 off center it should be fine to run.
thanks !!!