To store your carburetor over the off-season, drain the bowls by removing one of the bottom bowl screws and pumping the pump circuit completely dry. This will generally suffice, but an extra margin of safety can be obtained by pouring a mixture of leaded racing gas and Marvel Mystery Oil into the carburetor through the vent tubes, pumping the solution through the pump circuit, and then draining out the excess. Even better: run the same mixture through the entire engine, lubricating rings, valves, and cylinder walls, as well as the carburetor. If you use oxygenated fuel, alcohol, or any blend of ethanol, this maintenance step should be taken frequently through the season to combat corrosion. Now, this process will smoke you out of the shop, but it will help maintain the health of your fuel system.
Probably the most forgotten fact about the crate engine, whether GM, Ford, or Dodge, is that it has a compression ratio of 9.0:1 to 10.0:1. Another fact that most people do not realize is that compression ratios in this range require fuel octane ratings around 110. Using lower octane fuels often leads to detonation which can result in engine failure or leads to a decrease in timing which results in decreased potential power. Pump gas is not held to the quality and consistency standards required to ever be used in a racing application, and the idea of mixing fuel (pump gas and race gas) is a horrible idea. Let me say it again – NEVER use pump gas for a racing application. A good follow-up discussion is on our tech page. The next mistake commonly made with crate engines (and with most other race engines as well) is spark plug heat range selection. The very plug recommended by GM on the valve cover of their crate engine is wrong. First, it is a resistor plug, which is not good for racing applications; and second, it is about six steps too hot. Because of my years with Champion Spark Plug Company, [...]
1991 SUPERFLOW ENGINE TECHNOLOGY CONFERENCE WRITTEN BY: Dan VanderLey / Motorsports Engineer, Champion Spark Plug Co. Mark Twain quotation – “Thunder is impressive and thunder is great but it’s lightning that does the work.” Definition – A device which provides a gap in the combustion chamber of an internal combustion engine across which an electrical discharge may occur which initiates the combustion of an air/fuel mixture.The spark plug performs a simple function in a complex environment. CANDLE IN A HIGH WIND just as in the title the candle is affected by the wind’s characteristics, so in our choice of plugs we must consider not only it’s basic function but more importantly the “wind” it operates in. 1. PARTS AND ASSEMBLY A basic understanding of the parts and assembly will later help in the application and interpretation of the plug. (Cut-away plug below) PARTS A. Insulator – Aluminum oxide ceramic, must have good dielectric and mechanical strength, good thermal conductivity and resistive to heat shock B. Center Wire – Must have good conductivity and be chemically and electrically erosion resistant (Approx. melt temp. of std nickel is 2500 degrees Fahrenheit) C. Terminal Stud – Either solid post or removable terminal nut made from mild steel D. Shell – Extruded or bar [...]