Mitutoyo 511-Series Dial Bore Gauge

In automotive and light truck repair, most tools are designed for the trade. Simple hand tools might be common to industrial applications, but nothing is as time critical as automotive repair, which has led to lots of special, labour saving tools. If you rebuild engines for a living, or just want to do it once and not again for a long time, measuring what you have, be it journal diameters, bearing clearances or bore sizes, is critical. Cylinder bores are the heart of the rebuild, and whether to re-bore (and if so by how much) can determine whether or not the job is cost effective.

SSGM recently tested Mitutoyo’s 511-833 (part of the firm’s 511 Series) dial bore gauge on a standard aluminum V-8 bare block with dry liners that had severe ring blow-by. Mitutoyo is not a common brand name in most shops, but in precision industrial and scientific metrology, it’s a major brand and like the repair trade tool vendors, carries a large catalogue of time saving tools. The 511-833 dial bore indicator ships in a sturdy blow molded case with the base unit, extension bars, tools and a set of multilingual instructions.

The “511” is easy to use. We followed the simplified instructions and had the unit assembled in under five minutes. The design of the tool uses a three point contact with the bore, guaranteeing true diameter readings with simple handling.

A carbide ball tip prevents marring of the workpiece, making the unit ideal for measurements in soft aluminum parts like connecting rod big ends. Once set to the desired value, in this case 3.500 inches, the dial indicator shows how much under or over the bore is, simply by drawing the tool up and around the bore. This allows the tech to very quickly measure bore taper, ovality and overall wears, as well as any serious surface imperfections. Could you do this the old fashioned way, with a bore gauge and micrometers? Yes, but with this technique, multiple checks are required, easily a dozen or more for a careful job, which adds up time-wise in a multi-cylinder application like a V-8. In addition, the Mitutoyo “511” allows the tech to “sweep” the bore, picking up voids or pits that could be easily overlooked with the limited number of contact points available with traditional gauging. In our test block, one cylinder had a void in one bore that the Mitutoyo tool picked up immediately. That bore needed a new liner, and without the dial gauge there’s a real risk that the block would have been sent for a 20 “thou” overbore that wouldn’t clean up the issue, wasting time and money.

The “511” saved lots of time and effort. The series can be configured with a wide range of accessories to expand the range of measurements and the tool’s reach and for true precision junkies there are super-accurate ring-type standards available for bench testing of the unit. Precision measuring tools like the 511-833 aren’t cheap, but they’re much faster than conventional bore gauging, making the time saving significant in cylinder measurement as well as bearing bores, re-sized rods and multiple other engine tasks. And the other advantage of using tool and die quality measuring tools? The Mitutoyo unit can be tested, calibrated and if necessary, repaired by in house technicians at the firm’s Canadian office.

Is it worth the money? Considering how easy it is to invest four or five thousand dollars in a good rebuild of a high performance engine, the answer is clearly “Yes.”