Volume I, Issue 1, Page 52


The Idle-Eze assembly as installed in the Demon billet baseplate with accompanying milled slots to provide the necessary source of air to activate the idle-discharge circuits.  Air is drawn along the upper milled slots, through the Idle-Eze valve and exits beneath the butterflies.

The Demon Idle-Eze, an indispensable tuning aid for matching camshafts to carburetors. 

When upgrading the camshaft in your street machine, you may experience a change in the engine’s idle quality.  Until recently, the most common remedy for a camshaft-induced poor idle has been for engine builders to drill a hole in each butterfly or throttle plate within the carburetor. 

So let’s find out why the quality of idle can be so adversely affected by the installation of a performance or racing camshaft. And, what do such customized holes do to improve the idle?  What would be the correct diameter of the holes; how would you gauge that; and what are the consequences if the holes are drilled too large in the butterflies?  And perhaps the most informative question:  is there a better way to retain idle quality and throttle response while taking advantage of the extra power provided by a modified camshaft?

Matched to the correct components, performance camshafts offer impressive gains in horsepower.  But, due to their increased overlap (the period when the intake and exhaust valves are open simultaneously), idle quality can suffer because the difference in pressures above and below the carburetor butterflies has been altered.  The upper side of the butterflies mustattain greater than atmospheric pressure, and the underside must be closer to a vacuum, which creates the signal that activates the carburetor and provides the subsequent flush of fuel-and-air mixture.

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