HarleyTechTalk

Is it normal for Barrels after using torque plates for boring and honing ,measured perfect with plates on after honing at room temp, to be out of round when remeasuring with out plates ? my friend a engine reconditioner has had a customer come back saying they are out of round, when he measured them ,we know when bolted down on to engine block, this resembles using torque plates in the first place , for this purpose ,i have lent him back my torque plates to bolt back on for re measuring,cheers Barny

It's the reason to use torque plates in the first place.

so it is normal ? has any one measured them ?and how much may they differ in the bore ?

Quote from: barny7655 on January 10, 2023, 08:50:05 PMso it is normal ? has any one measured them ?and how much may they differ in the bore ?

Yes it is normal for them to be out of round without the torque plates on. They measure them after boring/honing only with the torque plates on. The reason why is that they KNOW that the dimensions are going to change once the plates are taken off. They know from years of experience. Remember Harley cylinders are not anything like a multi cylinder engine block where each cylinder helps the other to stay in place.

It doesn't matter how much change there is. Every cylinder is different because the metal, while close, varies in each cylinder. This will give you different deflection in each cylinder every time.

Barny what torque did you tighten em down to? If using mls head gaskets the torque should be the same in plates.

Two things, yes it is normal for the jug to be less than true after the plates come off.  And rough handling will also chase the true away.  The bigger the bore, the more fragile the just is with oems.

You can bore and hone a cylinder perfectly straight and round, take it out of the torque plates, and it'll be distorted.

Interestingly, though, if you put it back in the torque plates and redo the measurements, it's better, but it won't perfect the way it was when you originally bored and honed it. They don't exactly repeat.

So if you put it back in the plates and measure, don't expect it to be perfect.

Also keep in mind that a cylinder in a running motor is not uniformly heated.

The whole thing is an inexact science. We just do the best we can and it seems to work. But it's not perfection.

thank you all,what happens in my industry as a mechanic you always get some one that knows better , since i have never measure the out of round after removing plates , but i think these answers will give me the advice to inform people that ,its normal for this to occur  , cheers Barny

Got me wondering if this also applies to the same degree with 103 to 110 Harley steel lined jugs?