how much crankshaft endplay on a small block shevy is considered damagingly too much?

I am in the middle of the motor and since it was a straight forward rebuild I didnt check it with just the crank in there, I only checked the bearing clearances on the mains and rods as I was assembling it. As I was putting a socket onto the snout to turn the motor over (all rods and pistons in place and torqued, oilpump in and torqued) I notice the crank moves backwards quite a bit, I measure it and its just under a 1/16th of an inch!!!!!
Is this too much to run? I used the correct bearings.

 

We are talking thousanths, not fractions here.

The spec should be .003-.010

Bret

 

I'll measure it with a feeler then, I was just eyeballing it and didnt think it should move that much.

 

Measured it with feelers and it came out to .018. What can I do besides a new crank to tighten that up? the thrustbearing?

 

The rear main bearing is used to control that.

The problem is there is not a good solution to your problem other than maybe a new main cap on the rear main bearing, but it's most likely a crank that had that spec off.

Bret

 

I see exactly what youre talking about. I have a standard SBC 350 crank setting here and anfter I read your reply I measure both through there, the used eagle crank I was trying to used looks to be worn here and is definately wider where the thrustbearing is as well by .0082 (if I'm reading my caliper right).
I guess a new crank is what I need.

Dad-burn it I just had this thing balanced too (180$)

One other question, could I bring the new crank (buying the same kind) along with the old crank and my flexplate and harmonic balancer and would they be able to balance it from how the old crank, or should I bring everything back to them?

 

Is it true that there are oversized Thrust bearings? if so whats your thoughts on these? Besides this clearance the crank is good.