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Intententional .001 taper during engine boring?; Never heard of this before but someone told me they like their engines done this way...
Topic Started: Sep 25 2012, 08:44 AM (505 Views)
cwatkin


A mechanic I talked with told me that it is a good idea to have cylinders .001 larger at the bottom than at the top of the bore. I have never heard of this before and was wondering the exact purpose. This guy has built all kinds of engines for racing applications so I think he would know what he is talking about. He indicated this slight taper really helps with oil consumption.

Anyone ever heard of this? If so, is it ever done on Metro engines?

Conor
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75monzatc
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just jeremy

There are many different things that people swear by, but the way I understood it the less taper, the better. What is listed as acceptable taper depends on how old you engine is, later model cars have alot tighter tollerances than say 60's & 70's engines. When you have taper in a cylinder, you will have ring flex which over time leads to metal fatigue and finally failure. I've always dealt with v-8s and tried for the truest bore on my race engines, no taper at all. I use a van norman boring bar and a torque plate when honing(steel or aluminum based on what type of head I am installing) to simulate having the head bolted on the block after boring so there is no deflection possible from head bolts. On your stock motor, most of that is overkill for the price involved to perform. The main thing is that as an engine wears, most of the taper starts at the top of the cylinder, that is when the oil starts getting through. Here is a link to a pretty decent article explaning about cylinder bores, might help answer your question. http://www.enginebuildermag.com/Article/83759/boring_and_honing_tips_and_tricks.aspx
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