"I have a 1990 7.4L Mercruiser
"I have a 1990 7.4L Mercruiser with a Thunderbolt IV ignition that I can't get the timing to 8 deg TDC; it stays advanced at approx. 25-30 deg. BTW, the engine starts easy/immediately, idles less than acceptable with the slight cackling sound. Upon rotating the distributor clockwise in an attempt to retard the timing (and adjusting the idle to compensate), the engine barely runs and then kills. I’ve verified TDC by putting the timing marking on zero (0) deg and inserted a Bic plastic pen (eliminate metallic damage) in spark plug hold thereby feeling the top of the piston, while verifying the rotor position, which points to #1 on the distributor. And verified firing order. I've replaced the ignition sensor, dist. cap, rotor w/timing wheel, spark plugs and coil ... all Mercuiser/Quicksilver components. I did not replace the spark plug wires (8mm, three years old).
Any suggestions or comments are welcome in order to get the timing correctly at 8 deg TDC."
"I have a 1990 7.4L Mercruiser with a Thunderbolt IV ignition that I can't get the timing to 8 deg TDC; it stays advanced at approx. 25-30 deg. BTW, the engine starts easy/immediately, idles less than acceptable with the slight cackling sound. Upon rotating the distributor clockwise in an attempt to retard the timing (and adjusting the idle to compensate), the engine barely runs and then kills. I’ve verified TDC by putting the timing marking on zero (0) deg and inserted a Bic plastic pen (eliminate metallic damage) in spark plug hold thereby feeling the top of the piston, while verifying the rotor position, which points to #1 on the distributor. And verified firing order. I've replaced the ignition sensor, dist. cap, rotor w/timing wheel, spark plugs and coil ... all Mercuiser/Quicksilver components. I did not replace the spark plug wires (8mm, three years old).
Any suggestions or comments are welcome in order to get the timing correctly at 8 deg TDC."