Engine Measuring Tools

Engine Building Measuring Tools

Building engines requires the mastery of many measurement techniques. You must understand volume, length, time and more.
Building engines requires the mastery of many measurement techniques. You must understand volume, length, time and more.

The French created a measurement system in 1790 called the metric system. While the U.S. has never managed to switch over to it completely, as we were supposed to in the latter half of the 20th century, most automotive techs are familiar with it today because of the fasteners and components on late model vehicles.

Building engines requires the mastery of many measurement techniques. You must understand volume, length, time and more. One tooling supplier said that engine builders used to measure in thousandths, but today tolerances are such that in many cases that isn’t good enough and you need to measure in the ten thousandths or more.

We talked to some tooling suppliers to see what the latest tools they had to offer engine builders to help them stay on top the measurement game. The tools that are most needed today are really about measuring any and all components to ensure the integrity of the engines you’re building. One tooling expert said that all engine builders need a quality set of micrometers, dial bore gauges, spring testers, surface roughness testers and vacuum testers as well. But that is just a start.

Performance Trends

Running a successful machine shop today requires more than a good set of micrometers, you must also keep very accurate records of the engines you build. Kevin Gertgen of Performance Trends offers various software for engine builders including the Engine Build Log Book. He says it is a “must have” for any professional engine building shop. Not only can you record all your engine information, you can have the program do calculations and checks, like estimating piston to valve clearance, valve spring bind clearance, cranking compression pressure and more.

Gertgen says you can supply your customers with professional, organized printouts, and even the actual data files which they can review and print with our free demo version. The program has 7 levels of an engine build you can choose from, from a simple Machined Short Block Only, to a Complete Short Block or Complete Head, or all the way to a Complete Engine with Dyno Results.

You can customize the program to match how your shop does things.  For example, you can tell the program your own preference for checks, like to flag out clearances that are higher or lower than your limits.  You can also eliminate inputs you do not use.  You can choose to enter multiple inputs for selected inputs, like cranking compression, leakdown, or just one nominal number.

Gertgen says that Performance Trends also offers an electronic measurement equipment such as its Valve Spring Tester that uses electronics to measure spring force and height to accurately measure spring rate, spring force at seated and open heights, coil bind and more. You can test springs up to 4? tall and 2,500 lbs, or as low as 100 lbs. and less than 2? tall. The system is available in either a manual or automatic (pneumatic) package, or as an affordable retro-fit kit for other types of testers.

Sunnen Products

Sunnen offers a few tools that engine builders would find hard to live without. They are the creators of the dial bore gauge for checking cylinders before and after honing, as well as rod dial bore indicators. These gauges have been a staple in shops for years, but now they offer a new twist on an old favorite: an electronic dial bore gauge.

Sunnen’s Phil Hanna says that their dial bore gauges are now available with optional large LCD indicators. Simple design and quick setup make fast go/no go judgments a snap. The optional, large-readout electronic indicator is available on its entire range of dial bore gauges. Highly visible in the shop environment and a quick reference for multi-tasking operators, the new electronic gauges feature precision indicators with 6 digit LCD readouts, 11 mm character height and three large buttons for easy operation.

Capable of checking bore sizes from .054? (1.37 mm) to 12? (300 mm) and bore lengths up to 24? (600 mm), Sunnen’s electronic bore gauges allow users to set upper and lower tolerance limits for go/no go judgments, which are then displayed in full-size characters. Standard analog indicator-equipped gauges read out in tenths (0.002 mm), models with five-tenths (0.010 mm) read outs are also available. Hanna says operators can easily toggle between inches and metric measurement read outs.

The electronic dial bore gauges are accurate to ±0.00012? (±0.003 mm) with 0.00005? (0.001 mm) resolution and provide the ability to perform scaling calculations, judge tolerance, hold data and perform general comparison measurements. Internal calculations using a simple [F(x)=Ax)] formula. The gauges are ideal for shops honing production runs of parts that require SPC data at multiple points in the bore. Data output via SPC cable enables direct transfer of bore measurements to a computer for use with SPC software.

The indicator face displays the spindle’s absolute position via an absolute linear encoder capable of relocating the origin, even after the power is turned off, for quick-start, multi-point measurement. The positive/negative count resulting from the spindle’s up-and-down movement can be toggled, and the indicator face can be rotated 330 degrees, for easy reading at virtually any angle.

Hanna says the gauges are adjustable to ensure proper centralization over the entire diameter range for more accurate centering action, even if the gauge is tilted off the bore axis. A right angle attachment is available for conditions where the gauge is difficult to read or total gauge height is an issue. Blind hole probes and probe extensions are also available. Probe extensions are 2.5? (63.5 mm) long, and up to three extensions can be assembled together.

Hanna says their gauges feature all-carbide gauging points for applications where exposure to extreme wear conditions – like heavy production, rough workpieces or abrasive materials – is a factor.

King Electronics

Many engine builders will tell you that accurate ignition timing is the real key to obtaining maximum horsepower and efficiency out of an internal combustion engine. But virtually no one knows how accurate his engine’s timing is, and if the mechanical and vacuum advance curves are functioning properly, or if the breaker points or electronic ignition module is providing the correct dwell for a hot spark. Now, with a King Electronics D16 or D16-T distributor machine you can quit guessing and actually test these components including the complete ignition system to see if your ignition is performing properly, and if there are any hidden problems like distributor shaft run-out causing erratic cylinder-to-cylinder firing.

King’s distributor machines are a blend of the latest electronics and innovative mechanical features. The 1 hp motor is capable of smoothly spinning a distributor or magneto to 11,000 rpm, and the digital tachometer is accurate to 1 rpm. Whereas the older machines attempted to grasp the distributor shaft with a three-jaw chuck, King uses an ER-40 collet system that totally eliminates slippage. The distributor tester’s housing is machined out of billet aluminum that is black anodized with laser-etched symbols. An internal tubular frame is TIG-welded, as is the roll-around stand (standard on the Premium D16, optional on the Pro D16-T).

Even more impressive is what these machines can do. You can test complete ignition systems from distributor to individual spark plugs. They accept all types of distributors and magnetos including breaker points, magnetic pickups, optical sensors, electronic modules, and they even include a high-tension inductive pickup for magnetos. An optional 1.5 hp motor will spin even the largest Top Fuel magnetos.

Analog and digital ignition boxes can be checked for output and rpm activated switches for delaying advance curves, setting rev limiters and nitrous oxide timers within 1 rpm accuracy. According to frequent Engine Builder contributor, Len Emanuelson: “There is nothing more difficult and frustrating than trying to troubleshoot a faulty ignition box.” With this system, however, that may be a thing of the past.


“We all know that in high performance applications, putting cylinder bores, lifter bores, deck heights and ports in the right places (blueprinting) makes more horsepower. The ability to probe on the Rottler CNC block machining centers and the Rottler head porting machines makes that job much simpler and can actually give our customers the visual tools to sell their customers on doing the job correctly,” explains Rottler’s Ed Kiebler. “We now have the capability to determine cylinder bore locations, lifter bore locations and deck heights in a matter of minutes vs. hours of measuring the old fashion way.”

Kiebler says most engines builders understand that maximum horsepower gains are realized in the area of valvetrain and cylinder heads but it’s also important to have the correct deck height and cylinder bore locations in relationship to crankshaft. “Now you can probe the lifter bore locations automatically and determine how far off those locations are to the centerline of the cam bores. The same can be done for the cylinder bores vs. crankshaft relationship,” he says. “Deck heights can be probed in 8 different locations on both banks on V-series blocks or 8 different locations on inline blocks. Once the deck height is determined you can mill the block to exact deck height without the need to measure each time you make a milling pass.

Cylinder head porting is much simpler and much more consistent with half the effort in large part to the ability to probe a properly ported intake and exhaust port and then replicate it in the rest of the ports on a cylinder head. The ability to probe on the Rottler cylinder head porting machines in conjunction with the Rottler porting software reduces the digitizing/blueprinting portion of that operation to hours instead of days.”

Trend Performance

Valve train geometry is when the rocker arm tip moves from the intake side of the valve stem tip, across the center of the tip (at approximately mid lift), to the exhaust side of the valve stem tip (at full lift) and back. Using an adjustable pushrod such as those available from Trend Performance, allows engine builders to choose the right size pushrod every time.

Pushrods lengths are measured starting at .140 gauge diameter, which means if you start at the center of the ball end and measure .070 in each direction (totaling .0140) then wherever this distance intersects with the radius of the pushrod is where the measurement is actually started.

The rate of the radius will affect the overall actual length of the pushrod. The reason for choosing this measuring standard is that some manufactures have larger or smaller holes with different chamfers, and these factors will change the measured length. Two pushrods with the same actual .140 gauge diameter lengths but manufactured by different suppliers may show different lengths.

To alleviate this problem, Trend’s pushrod length checkers are marked with a standard length that is laser etched into them. This number represents the gauge length of a part (.140 gauge diameter) with the two halves tightly screwed together. Extending the checker one rotation lengthens the gauge length .050. For example, a pushrod etched 7.800 screwed apart one rotation would be: 7.800 + .050 = 7.850 gauge length. Therefore you would order the part number from the catalog based on this measurement.


BHJ’s O-Ring Groove Cutter system can be used to cut grooves for conventional stainless steel O-ring wire for copper head gaskets, copper O-ring wire for “MLS” gaskets, as well as “fire ring” installation in diesel and drag racing applications.

The cutter head can be used on BHJ big-bore register plates as well as the company’s small-bore plates. The Big-Bore Adapter Ring should either be installed or removed as necessary per application.

Absolute concentricity of the wire groove to the receiver groove is ensured with this system when both a wire groove and receiver groove are necessary. When used correctly, the O-Ring Groove Cutter Kit will produce grooves that are well within the dimensional tolerances of any given head gasket and/or ring manufacturer. BHJ recommends referring to the head gasket manufacturer for O-ring groove dimension starting points.

Goodson Tools

Goodson’s Valve Spring Compressors include two top-of-the-line Valve Spring Benches. The pneumatic model (PSB-5000) is designed to work on virtually any multiple valve head and is ideal for heads with recessed springs. A key feature is the pneumatic valve support that holds the valve closed as you compress the spring.

This model has all of the features you’d expect in a quality valve spring press including a head that adjusts 25? in either direction, a table that adjusts 45? to the front and 30? to the rear and a foot pedal for hands-free operation.

Goodson’s manual Valve Spring Bench (CF-500) is also designed to work on heads with recessed springs. As with the pneumatic model, the head can be adjusted 25? to the left or right for canted valves.

What tools do engine builders need to rise above mere mortals? Electronic tools do offer several advantages and seem to be taking over the market from analog units. While analog is still acceptable, it doesn’t record data for easier  comparisons to spreadsheets or records.

What tools would you like to have in your arsenal? Drop us a line and let us know at [email protected].

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