Hello,


There are a few things that I would do to reduce hydrocarbon emissions.

1. Adjust the valve clearance.

2. Install new spark plugs.

3. Clean the manifolds.

4. Replace the fuel injectors.

5. Recondition the valves.

6. Recondition the bottom end.

7. Replace the catalytic converter.


Changing the spark plug wires may increase the high tension voltage slightly. This could increase the radius of the arc an infinitesimal amount leading to a proportionally small increase in flame front propagation speed. The larger the initial arc radius, the smaller the time until total combustion.


1. Fitting new spark plugs will increase the ignition arc radius via reducing the gap between the electrodes.

2. Adjusting the valve clearance will increase the amount of time the intake and exhaust valves are open. This will result in a more complete combustion.

3. Cleaning the intake manifold will reduce the amount of high molecular weight hydrocarbons drawn into the cylinder. The lighter a fuel molecule, the faster the pyrolysis. The faster the combustion the more complete it is. Cleaning the exhaust manifold will enhance the elimination of exhaust.

4. Replacing the fuel injectors will lead to further atomization of the fuel. This will lead to a quicker and more complete combustion cycle.

5. Reconditioning the valves will increase compression. The increased compression will lead to a more complete combustion.

6. Reconditioning the bottom end will also increase compression.

7. Replacing the catalytic converter will increase the active surface area of the catalyst. Increasing the effective surface area will increase oxidation of unburned hydrocarbons.


You might do well to gamble with a retest.

Good Luck,
Goatman