The total of the items I bought at Grainger is $23.66 (this is with the tax added in). I could have saved a little money if I would have shopped around. I know you can get the air line couplers and coupler plugs cheaper. I also know that I could have got the pressure gauge about a dollar cheaper. I also could have gotten the nipple and reducing coupling for about one dollar for both at a pipe supply store. But, I was there so I just got it all at once.
This is a list of the parts from NAPA. The total here was $6.17 (including tax). This brings the grand total to $29.83. This is going to save you about $10.00 over buying one (not including shipping and handling). Maybe even a little more if you shop around for some of these items. Now I am going to show you how to make the sparkplug adapter from some more parts that I found at Discount Auto. You will have to buy an o-ring but I didn't add this on the parts list because I already have one. I don't think it would be more than a dollar though. I found an adapter in Discount Auto that is called a Spark plug NON-Fouler. What it is intended for is to screw in the sparkplug threads and then screw the sparkplug into the adapter. I bought the 14mm short plug adapter. It was $1.99. 1/4" NPT pipe threads and the 14mm spark plug threads are very close to matching. I used a 1/4" NPT pipe tap and reathreaded the inside of the adapter. Now the air hose with a 1/4" pipe thread will fit inside. Make sure you use good Teflon Tape on all of the screw fittings. This will ensure a good seal.
Make sure when you are doing the leakdown test you have a way to LOCK the flywheel. Remember you are applying 75-100psi to the top of the piston and that can send the piston flying down the cylinder fast enough to hurt you. As you can see in the pictures above, the way I do it is I take the Briggs flywheel holder and put on the flywheel and then C-Clamp the motor to the table with two C-Clamps. This ensures the flywheel will not move when pressure is applied to the cylinder.
| 75 lbs. | 90 lbs. | 100 lbs. | Percentage |
|---|---|---|---|
| 74.4 | 89 | 99 | 1 |
| 73.5 | 88.2 | 98 | 2 |
| 72.7 | 87.3 | 97 | 3 |
| 72 | 86.4 | 96 | 4 |
| 71.2 | 85.5 | 95 | 5 |
| 70.5 | 69.7 | 94 | 6 |
| 69.7 | 83.7 | 93 | 7 |
| 69 | 82.8 | 92 | 8 |
| 68.2 | 81.9 | 91 | 9 |
| 67.5 | 81 | 90 | 10 |
| 66.7 | 80.1 | 89 | 11 |
| 66 | 79.2 | 88 | 12 |
| 65.2 | 78.2 | 87 | 13 |
| 64.5 | 77.4 | 86 | 14 |
| 63.7 | 76.5 | 85 | 15 |
The way to perform this test is make sure the air pressure supply is at least 10psi greater than the testing pressure. I have my air compresser set at 100psi. I normally test at 90psi. Before you hook up the leakage tester to the air line make sure you have the regulator turned all the way down. Now, hook the regulator to the supply line and slowly turn the knob on the regulator until the pressure comes up to the test pressure you want. Lets say we are testing at 90 psi. Now, hook up the line connected into the sparkplug hole. Look at the gauge and write down the pressure or if you have the chart in front of you look at it to determine the leakage percentage. You can also listen to see where your leakage is coming from. If it is coming from one of the ports your valves are not sealing and you need to go back and do some more valve work. If it is coming out of the valve chamber cover (breather tube) your rings are not sealing. 2%-4% is normal for a fresh motor. 4%-10% for a motor that has races on it. Anything over 10% and you need to do some motor work.
You can reach me at phinishline@yahoo.com for comments, questions, and suggestions.