Went out on the water today after doing tune up including Cap Mallory, Rotor Mallory, wires 8mm Mallory, plugs AC Delco. When I started the engine at the ramp, had a tough time to idle which had nothing to do with idle speed screw adjustment. No misfire under load but had big loss in power at WOT.
Checked all wires from cap to plugs and was correct. Had a feeling the timing was retarded a little. Did not have my timing light but just advanced the Distributor a little until the idle speed was at a normal speed. Usually time to 30 BTDC but will have to dial in timing next time. Anyway the power was restored with the advance and ran smooth from idle to WOT.
I timed the motor two months ago and ran great at WOT but was a little rough at low RPM which is why I did the tune up.
My question is how did the timing become retarded just by changing the plugs, wires, cap and rotor? I guess the full tune up requires a recheck with the timing light.
Now the motor runs the best it ever has just need to fine tune the timing back to 30.
I was just surprised that those few changes required an advance of the timing?
Any ideas as to why the timing needed readjustment?