Helpful tips

What should my timing advance be?

What should my timing advance be?

That is typically 15-35 degrees before TDC (top dead center) of the power stroke depending on the engine speed. Best power is achieved when ignition timing is set to fire the spark ahead of time to reach that peak pressure at about 2 degrees after TDC.

What should ignition timing advance be at idle?

between 5-20 degrees
Most engines have between 5-20 degrees of ignition advance at idle. This is referred to as initial timing.

What happens if your timing is too advanced?

If ignition timing is too far advanced, it will cause the fuel-and-air mixture to ignite too early in the combustion cycle. This can cause the amount of heat generated by the combustion process to increase and lead to overheating of the engine.

How do you know if your timing is too advanced?

Some things to look out for:

  1. Engine knocking: Engine knocking occurs when the air-fuel mixture is ignited too soon in the cylinder.
  2. Decreased fuel economy: The timing of the spark plug is crucial during the ignition process.

How do you check advance timing?

Rev the engine past the point where your mechanical advance is fully engaged. (Usually, 3,000 – 3,500 rpm will do it.) Watch the timing mark on the harmonic balancer using the timing light. Rotate the distributor until the timing mark lines up at zero with the light.

What happens when vacuum advance fails?

Eventually the deterioration will reach the point that the vacuum advance no longer adjusts the timing, causing the vehicle to hesitate when the engine attempts to move the vehicle’s weight. In addition to this lack of power, a vacuum leak can also cause the engine to idle roughly or even stall.

Does advanced timing lean or rich?

as was brought out, the timing has little effect on rich/lean issues and even less on a computer controlled engine. the ecm looks at all of the parameters and calculates the needed corrections to a burned in fuel map.

What causes timing to advance?

Ignition Advancing vs. Ignition timing advancing means that the spark plugs are firing earlier in the compression stroke, farther from TDC. The air and fuel mixture in the combustion chamber doesn’t burn right away. Ignition timing retarding causes the spark plug to fire later in the compression stroke.

How much timing does vacuum advance add?

A vacuum advance unit can add up to 15 degrees of advance.

Does advancing timing increase idle?

Our experience shows that connecting the vacuum advance to a manifold vacuum source will add timing at idle and improve idle quality in gear with an automatic transmission.

What kind of advance plate does a Hei use?

THE ADVANCE SETUP: Centrifugal and vacuum advance. Centrifugal advance assy. on the HEI is pretty darned good. The stock weights and advance plate are perfectly acceptable for all but the highest HP/RPM engines.

How many degrees of mechanical advance does a Hei have?

Once more the setup for 35 degrees of mechanical advance: 14 initial + 21 centrifugal + 12 Crane adjustable vacuum advance without EGR = 47 total. 14 initial + 21 centrifugal + 16 Crane adjustable vacuum advance with EGR = 51 total. 14 initial + 21 centrifugal + 22-24 stock vacuum advance = 57-59 total.

Can you change the advance curve of a HEI distributor?

There is NO WAY to change the advance curve of a computer-controlled HEI distributor- timing is controlled ENTIRELY by the ECM’s programming! The only change you can make in the advance curve, other than buying an aftermarket performance chip for the ECM, is to manually advance the base timing (usually worth a little HP by itself).

What kind of springs to use on HEI distributor?

(The medium and heavy springs in these kits can be used with stock weights.) Heavier weights bring in the curve quicker, as do lighter springs. However, very light springs will fatigue quickly, and the weights will stick more toward the open position, causing hard starting and poor performance.