Forum » Engine Building Fundamentals » One time use OE bolts and torquing down for bearing clearance measuremnts

One time use OE bolts and torquing down for bearing clearance measuremnts

Engine Building Fundamentals

Discussion and questions related to the course Engine Building Fundamentals

= Resolved threads

Page 1
Author
138 Views

Was just wondering if there was any advice when measuring bearing clearances.

On a particular build I'm busy with, customer has supplied OE main bearing bolts.

When I torque the main caps down to measure bearing clearance. I've now used the one time use bolt which I will have to remove again assembly.

How does one get around this? Can i use the old main cap bolts for the clearance measurements and retain my new bolts for final assembly?

it is not a issue to reuse them in my experience when they have not had a heat cycle thu them

Awesome thank you. Was just worried wanted to double check

I would agree with head gaskets, mostly, - but with "one time use", or any other type of fastening where the fastener is deliberately taken beyond the elastic limit, it really shouldn't be re-used as, technically, it's already been taken to a fail point which it won't recover from.

If you're just checking clearances and crush, I would re-use the old bolts for that, taken to the initial torque level. If it were an alloy block and/or girdle, which may also deform slightly, and I were checking for bore distortion, there is an arguement for springing for a set of bolts just to check it, but, again, I would re-use the old bolts and also angle tighten them as required - there will be a slight difference in clamping force, but not enough to worry about - and, besides, if you're using OEM spec fasteners you're just duplicating the stresses that the engine has before - it isn't like you're using aftermarket studs with a different nut pitch which will affect the clamping force.

So, IMO, ONLY use the new bolts for the rebuild IF they had been torqued but not angle tightened during the dummy build(s) - it's the last bit that imparts the permanent deformation. Your engine, your call, though.

That's what I was initially thinking use the old for the dummy for measurement and the new for the build.

Thanks for your input appreciated. If client is as keen on being thorough as I am then maybe he will accept the additional costs for new set of bolts for dummy. I'll let him wiegh in.

Thank you