The latest resident of Jim’s Garage is a beautiful Mazda Miata. It is a 1996 with just under 33,000 miles on it. The owner had already had some modifications done primarily to the suspension a few years back. It has Tokico Illlumina adjustable shocks, an adjustable rear anti roll bar, springs that drop it down a couple of inches, a shock tower brace up front, Jackson Racing exhaust and cold air intake, and probably the shortest throw shifter I have ever experienced.
First on the list was to refurbish and replace the brakes. This is not a track car, but a exceptionally fun street car. So we picked up some Brembo drilled rotors and a set of Hawk pads that were appropriate for the street. I would not recommend drilled rotors for track use, but this was not the case here.
The flexible brake lines had already been replaced with braided stainless steel lines. The rotors and pads were OK but they needed to be freshened up.
When we changed the rotors and pads we also took the time to clean up the calipers, which were corroded, but in fine working order, and give them a nice VHT black finish. This really set off the cadmium plated rotors and will keep the brakes looking sharp. We consulted with the owner and chose black instead of something like a red. This is a great car and red would have made a statement that just would not have fit this car’s personality.
This Miata is no wall flower either. We took it out to bed in the brakes and fell in love with this pocket rocket. It just begs you to drop the top down and look for some curves and we have the sunny North Carolina weather to do it in.
We felt that the suspension modifications were very appropriate, but needed a bit more tuning. The Tokico shocks are very easy to adjust. The adjustment points are right on the top of the shafts and easy to get to. A small flat-bladed screw driver is all that is necessary and the adjustments affect both compression and rebound. I backed off one click on the front shocks to the #4 setting and left the rears at the #3 setting they came in with. The car felt like it still understeered so we took advantage of the adjustable rear anti roll bar and set it on the middle setting.
Now the car was much closer to neutral and very toss-able around corners. This is a very fun car. I only wish it had an LSD rear differential.
The power was very good in the lower RPM ranges, but seemed to lose something as you advance through the mid to upper range. I pulled the spark plugs and it was clearly time for new ones. The center electrodes were worn and the gaps had widened. We have a set of NGK iridium plugs on the way along with new NGK plug wires.
With the spark plugs out we took a flash light and peered into the spark plug hole to see the condition of the piston tops. They were covered with carbon. Time for the miracle of Mopar Combustion Chamber Cleaner (MCCC). I had discovered this stuff when I was modifying my Mistubishi Eclipse GSX. It was a turbo car and the factory ran things rich in order to protect the engine from the higher boost levels. While this Miata was not turbo charged it had accumulated carbon on the piston tops and the combustion chamber over the years and it was affecting performance.
MCCC works great on getting rid of the black carbon. First step, with the help of a volunteer, was to run the engine and spray MCCC through the intake. This would get rid of a lot of the deposits in the intake and behind the valves as well as soften up the carbon in the combustion chamber area. To do so we disconnected the PVC hose from the PVC valve and pushed a turkey baster minus the rubber bulb into the hose. This would be where we would spray in the MCCC. One person would keep the engine running while the other would spray in the MCCC. The engine would need to be kept as close to 1000 RPM as possible so as not to over heat the catalytic converter.
During this process clouds of smoke would be emitted from the tailpipe as the deposits were loosened and ejected from the engine. After the can was all used up the PVC hose was reconnected and the car taken for a short run. Then it was brought back into the garage so all the spark plugs could be removed. This was so another can’s worth of MCCC could be sprayed directly into the spark plug holes and on to the piston tops.
This is something that needs to be done with plenty of ventilation. The MCCC also needs to sit in the combustion chamber for awhile and soak off the carbon. After an hour or two I used a vacuum tool to suck out the fluid through the spark plug holes. It was full of carbon (good thing!). The tool I used is also used to suck brake fluid out of a reservoir. DO NOT use a regular vacuum cleaner or shop vac for this.
Then the spark plugs were put back in and the car taken for another drive to blow out the rest of the deposits. The oil will have to be changed as the chemical and carbon deposits need to be flushed out of the oil as well.
We will be going through the Miata some more. Refreshing the anti-freeze, changing out the radiator hoses and heater hoses, putting on a new drive belts, and a new fuel filter. We may even have a chance to do some engine compartment dress up.
Stay tuned for the conclusion.