Re: Engine Timing

Posted by Tim Cole On 2020/3/29 8:45:51

I always hooked up a hand vacuum pump to the distributor tube. The unit should hold vacuum. Additionally, the unit feed is ported vacuum so the timing should react per the service manual specifications for a given amount - somewhere in the area of 11-15 inhg, but don't hold me to it. In other words, the unit doesn't need to be stressed to 25 inhg to be tested. You also can watch the breaker plate reaction visually using this method.

As well, timing is worth little if the dwell varies when you raise the rpm to 2,000 rpm. Varying dwell indicates a worn distributor shaft, breaker unit, and possible drive gear wear. This means the timing is not steady and can cause intermittent pre-ignition. This can cause engine overheating.

As for visual inspection of engine noises, you can buy instrumentation to measure such using a volt meter or DSO. The sensors can be glued or bolted to the motor with the wires run into the passenger compartment. Another method is to bolt a long copper tube to the motor and measure the resonance through the tube using a microphone. This will prevent distracted driving and the risk of crashing the car. This is also an easy way to isolate various engine noises by cylinder, chassis noises and rattles. On the proving grounds it is the only safe way to do such at speeds over 140 mph.

That's it for now. I have a paper copy of Dr. Zhivago and a higher mathematics book to work through to keep me from getting sick.