Ignition Timing and Webers

[Gaz64]

Originally Posted by wolf k

Connected a vacuum gauge to the tap on the IDF carb, turns out that it is a ported tap. Had a nice steady needle, it was low at 7 in.hg at 1500 rpm, but only drawing from one cylinder. I do have a mild camshaft.

So although you only have 4 ported nipples, if you tee all the ported nipples together, you should get a higher average reading.

[wolf k]

Originally Posted by Gaz64

So although you only have 4 ported nipples, if you tee all the ported nipples together, you should get a higher average reading.

Yes, probably. I was just testing if a single runner would give a steady vacuum signal. I conclude it does, at least with a mild cam. Therefore, I believe, one could run a vacuum advance distributor off a single carb, or runner without the plumbing between multiple runners. You would have to adjust the advance diaphragm for the lower than normal vacuum. I already have a mechanical advance only distributor, so for me it is a mute point, but for a future project perhaps.