VP "C" Series Racing Fuels show a lean appearance on spark plugs as compared to other racing fuels, this is do to the low Aromatic Hydrocarbon content in VP blended racing fuels. Aromatic hydrocarbons are the soot forming properties left over after the combustion process.
Listed below are the basic tuning characteristics of VP Racing Fuels.
1. Always set your timing before doing a plug reading, adjusting the timing afterward may change your plug readings.
2. Install a new set of spark plugs and gap the plugs at the recommended plug gap for the type of Ignition system you are using. Electronic distributors require a wider plug gap than point type distributors. Make sure you have the correct type of plugs and heat range, this information should come from your engine builder or an experienced racing engine tuner.
3. Note the jet sizes in the primary and secondary sides of your carb, make one full hard pass in drag racing or 8-10 hard laps in your circle track or road race car.
Upon exiting the track shut down the engine without allowing it to idle, coast or push the vehicle to the pit area for the plug reading, pull All of the spark plugs and keep them in the correct order of the cylinder they were removed from.
4. With the correct jetting the plugs will look some where between a new plug to a very light gray color, if there is a yellow tint present that means you are to lean, jet up 1 jet size on the primaries and 1 to 2 sizes on the secondary. If there is a green tint you are very lean and must jet up 1 to 2 sizes on the primaries and 2 to 4 sizes on the secondary side.
A spotty or solid dark gray color indicates you are to rich and must jet down for the right mixture. After re-jetting make another hard test run and check your plugs again until you reach the correct color.
It is always safer to run on the rich side, rather than the lean side when jetting.
Contact Smith Wholesalers, Inc., VP Fuels Distributor
North East Texas (903) 796-3186