Cylinder taper/out of round

A

Anonymous

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What is the maximum amount of taper and out round allowances? I took my block to a machine shop when I first tore it down. It was already bored .030 over, but had no ridge at all. I told them to check everything and see if I could get away with just a hone. They said it was fine, but I think they were wrong.
 

Excelerater

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May 22, 2003
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buy a bore gauge.....check it yourself
 
A

Anonymous

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Excelerater said:
buy a bore gauge.....check it yourself

I did. They have some taper. Two cylinders are about .0015 taper. I have a crappy Haynes manual that doesn't have maximum taper specs in it. Having trouble finding out if thats too much. Seems like too much to me.
 
A

Anonymous

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Thread starter
was there a torque plate on the block when you measured it? was the block at ~180 degrees?

.0015" is very little i wouldnt worry about it
 
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Anonymous

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Kingrat said:
was there a torque plate on the block when you measured it? was the block at ~180 degrees?

.0015" is very little i wouldnt worry about it

no, I have never had this engine running. just wanted to make sure i could get good ring seal with that amount of taper.
 
A

Anonymous

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no offense kingrat, but does anyone else have any input on this? engine builders?
 

budss396

Dragway Regular
May 22, 2003
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Evansville, Indiana
I can tell you from experience that you can get the taper off more than 1 1/2 thousants and have a motor still be ok.

round is also a relative deal, the bolt hole between the hole distort the bore from 0 to 4 thousants when torqued.

if the bore is more than 4 thousants out of round torque the head down with a new head gasket and run your dial bore gage up from the bottom and recheck it.

as long as you are not scufing the piston at the bottom, i'd run it.

JMHO

BUD
 

chevycopcar

Pro Stocker
Jul 19, 2004
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This is just my opinion, but if you don't trust your machinest, you should probably find one you do.
 

K-Star automotive

Amateur Racer
Feb 6, 2006
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York, Pa
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block

If this engine had any miles on it at all you will need to touch the hone up for the new rings...a good machine shop should be able to get the bores straight again.

Don't put much stock on what the tolerance of the bores are listed at in the books....If you found out what you can get away with an still be in tolerance you might get week in the knees..... When i finish hone i get all my cylinders within .0002" straight and round.....

But i have seen engines with more then .0015" taper run just fine...I would not let .0015" taper go in my shop but everybody has there own ideas....

BTW what engine is this...small block, big block...stock all out race????


Keith
 
A

Anonymous

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Thread starter
Re: block

K-Star automotive said:
If this engine had any miles on it at all you will need to touch the hone up for the new rings...a good machine shop should be able to get the bores straight again.

Don't put much stock on what the tolerance of the bores are listed at in the books....If you found out what you can get away with an still be in tolerance you might get week in the knees..... When i finish hone i get all my cylinders within .0002" straight and round.....

But i have seen engines with more then .0015" taper run just fine...I would not let .0015" taper go in my shop but everybody has there own ideas....

BTW what engine is this...small block, big block...stock all out race????


Keith

its a 406 out of a wrecked truck. It had absolutely no ridge in the cylinder and bore is right at .030 over for the most part. I want to build a strong drag engine with it. Would like to run 11's on motor. I just don't want to put a ton of money into a half-*ss block. Only two cylinders had .0015 taper. The rest were more like .0005. They are pretty good as far as being round.
 

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