No. I think.
The model 73010 is a two gauge unit. It would be used with a shop air supply hose connecting the tester to the compressor that would have its own regulator and gauge. A third gauge if you would.
The gauge on the compressor or shop supply line is set at 115psi to 125psi. Then a 20 foot hose or what ever you need to reach the tester and engine. The left gauge in the Longacre tester is adjusted to 100psi with that regulator and the reading for leakage is on the right side gauge. IE, compressor gauge is 115; left Longacre gauge is 100; right longacre gauge is 93; = 7% leak. With this setup, the short hose is already connected to the spark plug hole and to the tester.
With the single gauge unit you said you were building, it's done a little differently. 115-125psi at the compressor. Then 20 feet of hose. The regulator(has no gauge) is used to adj 100psi on the gauge(that is on the "T" between the orifice and female connect). Then the short hose is plugged into the testers connector. The gauge reading will drop at this time. If the gauge now reads 90psi, you have a loss of 10%.
Hopefully the regulator will maintain 100psi on the other side of the orifice. If that regulator had its own gauge, then you would know for sure. That's where the two gauge unit would be considered more accurate.
The two gauge unit would not necessarily have to have a detachable short hose, but it makes it easier to thread into the spark plug hole. You can also make up two short hoses for two different plug threads.
