Boring a block

F

fatfrog

Member
Whats a good piston to cylinder wall clearance with a stock replacement .030 b&s piston i know on clones its between .003 -.004 clearance was wondering if the animal is the same?
Thanks
 
Joe,
By "latest," are you referring to cnc,or a specific technology?
That certainly wouldn't be us. I've got a 30+ year old mill with DRO, oh yea, and a couple of EZ Bore set-ups. :)
It's kind of funny -- knowing how to operate a manual mill and lathe has become a lost art today. All they teach at tech schools anymore is programming and how to push a green button and a red button, which qualifies these same kids to get a job doing the latter more than the actual programming.
 
yes thats what i am referring to i no the basics of how u set it up to bore it an if u are off just a tad its toast. i know it would take a lot of time to make sure that u have it right on the older machines thanks
 
It really doesn't matter if it's a manual or cnc machine, if you don't take the time in the setup, you can still make scrap.
 
oldloco said:
yes thats what i am referring to i no the basics of how u set it up to bore it an if u are off just a tad its toast. i know it would take a lot of time to make sure that u have it right on the older machines thanks
Click to expand...


An EZ Bore does an amazing job and simplifies the centering process - and can also do offset bores and slant bores if you so desire.
I can align bore a cylinder with the EZ Bore in less time than it takes to indicate in a block on the mill.
For sure, you want to align off of the crank and NOT off of the deck (or bottom of the block) for engines we use in karting.

Even if you used a CNC, I am guessing that the set-up would still be very time intensive.

Measure twice and cut once, right?
I think that still applies. :)
 
Easy bore has 2 ways to center the boring bar. The boring bar is a 1" shaft sticks out of the top of the engine (bore) that centers off another shaft that goes in the engine in place of the crankshaft. The quickest way to center the boring bar in the center of the cylinder is to use the plastic plug that slides over the boring bar and fits in the top of the cylinder. This can be set up in minutes but it's judgemental and not real accurate.
The more precise way to center this boring bar is to attach a special EZ Bore dial indicator to the shaft and sweep it around the cylinder to get it within .0005" (1/2 thousand) of an inch centered. After 20 years it still takes me a long time to get this perfect.
Just like anything else good things take time.
 
^ That is correct.
Using their indicator is the best way to do this. The centering plug is only to get you close (in my opinion.)

It's still much simpler/quicker than dialing the bore in on the mill. :)
 
I still like doing it on my Bridgeport. Somewhat of a successful and an accomplishment feeling when done.
 
The early Honda hybrids had the bore 3/4" off center.
 
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