best vacuum port on a Series 1?

[jedwards]

Gentleman,
I have always been a fan of tuning an engine using a vacuum gauge, but can anyone tell me the best place to take the inlet vacuum pressure from?

The vacuum advance at the base of the carburettor appears the only spot however this is not always very reliable at the butterfly setup can confuse matters easily.
The S1 has no brake booster, so no usable port, so what does this august group recommend?

thanks in advance
Jeff

[series1buff]

Hi

This has been discussed on the UK series 1 forum. The only thing to do is drill and tap a hole in the inlet manifold.

Some types of engines seem to respond to the vacuum gauge method of tuning better than others do , don't know why this is so.

Tuning for me , is rather a hit & miss process on these series 1 engines , I noticed my engine kicking back on start up so I retarded the distributor a few degrees til the kick back stopped , it seems to be running fine !

[JDNSW]

If drilling the manifold, from memory the manifold has a water jacket to prevent icing, and you really don't want to drill into this!

[series1buff]

If drilling the manifold, from memory the manifold has a water jacket to prevent icing, and you really don't want to drill into this!

The water jacket inside the inlet manifold surrounds the carby base, it is nowhere near the two outer inlet ports

[JDNSW]

Yes - if drilling a vacuum port, just make sure you know what you are drilling into.

[jedwards]

126154 There is a convenient threaded hole already in my Manifold on the firewall side of the inlet and nowhere near the jacketed area ardour the carbs. I assume it is there as a mount for something that my 1953 80" does not have. This seems the most method as I can just drill through the centre, and use the existing thread for a plug and for a vacuum take off.

Any reasons why not?

thanks
Jeff

[JDNSW]

I'd be wary about that - I think it is a place for something to bolt on to, and I am not sure a hole drilled into it would go into the manifold itself - that bit on the end could be solid; I can't think of any good reason why it would be hollow!

[1950landy]

I'd be wary about that - I think it is a place for something to bolt on to, and I am not sure a hole drilled into it would go into the manifold itself - that bit on the end could be solid; I can't think of any good reason why it would be hollow!
The bracket for the hand throtle cable bolts to that hole

[B.S.F.]

It's quite save to drill and tap..W.

[jedwards]

It's quite save to drill and tap..W.

Many thanks. That is of great help.

regards and thanks
Jeff

[mfc]

I drilled in between the mount and the water jacket from memory( mines a 1955 and dosent have that plug beneath the bracket which holds the hand cable as above but from underneath)