Vacuum gauge

[Contours]

The gauge shows a fair reading only at tickover when tapped into the spare plug on the throttle body. Either my M40 is showing its high mileage or you cannot get a correct vacuum reading from this location. Just wonder which is the case here. Maybe one has to tap elsewhere in the engine to show a more favourable result.

[Speedtouch]

Normally, vacuum gauges are fitted to the inlet manifold, i.e., after the throttle body.

Vacuum is usually high at idle, or on the engine over-run.

[ChrisHC]

Correspondingly, the vacuum is low when the throttle is opened. This led to interesting times for those with the vacuum operated windscreen wipers of the past, they would pull out to overtake, put their foot down and their wipers would slow to a crawl.

[Speedtouch]

Indeed, on such cars as the old 1950s Ford Popular and Prefect.

[paultv]

I was stoked when I found a 6 volt wiper motor at the scrappy and fitted it to my 1953 Prefect!

Paul

[Speedtouch]

Quite an upgrade - must have made your neighbours green with envy, I imagine...

[paultv]

Ha! Ha! I have to admit that overtaking was nothing I ever had to deal with! and anything more than light drizzle made progress impossible. I think I paid a whopping £10 for the car in 1975.

Paul

[Contours]

How did this post end up back in 1953