Accurate Measurement Device

Engine Analysis Software

Over the years, we have developed The Engine Analysis Software and the limiting factor was ALWAYS the difficulty of ACCURATELY measuring all the dimensions.

Many devices have been developed to measure head clearance accurately. We used those initially. They worked for us, along with dial calipers and a high intensity light, to see when the ports closed. One-day, Norris Sparks, our Dyno machinist and part of our development group decided that the measurement system was not as accurate as needed. SO, Norris came up with a different approach. He, being a machinist, knew that a height gauge would be ideal IF a system could be developed to be able to measure the port heights of a liner accurately. He decided that the way to do it was to make a stem which would accurately snag the port. Following is the height gauge with the special stem installed. Following is the stem, highlighted for clarity.

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Using this system, we were able to get accuracy to 1/2 thousandth (.0005"). That was fantastic! Better than that, we were able to measure a complete engine and document it into The Engine Analysis Software in less than 5 minutes with +/- 1/2 thousandth accuracy. We have found additional uses for the depth gauge. We measure the TDC position of the engine with the liner installed, the head projection, top of liner/top of piston difference, etc. We also have a dial indicator, which mounts onto the depth guage, to use for measurement of piston travel.

A similar depth gauge can be purchased from any machine supply store for about $500. Norris has found it as an import at Precision Industrial Tool & Supply, Inc. (800-433-7487) for $195.00 (as of 03/2016) ( It is a 12" model #EHG-605 The pin is an EX4 hard pin with a ground flat area of about .015", ground ALMOST (.030"-.050") to the bottom. This allows the pin to lay against the liner and still stop on the port lip because of the .015" ground flat area. We also recently found a less expensive depth guage that can be found here: It is about $50.

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Other notes for EAP Registered Users:

Dr. Brian Callahan and I have developed a little auxiliary spreadsheet program to calculate the exhaust port area. This is an input item in the newest version of EAP for calculating the ideal tuned pipe. It will also be used in future versions for calculating time/areas. If you would like this little program you may download it from

ENGINE Analysis Software for the Serious RC Nitro Competitor



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