How much vacuum?

[David Simon]

I finally got a vacuum guage today to tune my carb. When I checked I had 20-21 in Hg and it was very steady. The book that came with the guage said this was good. Before I make any adjustments to the mixture, is this enough vacuum?
Also, how much vacuum should be on distibutor at idle, I had about 7 in Hg.
Thanks,
David

[Tubro]

Well truthfully it how much vacume it holds is not really important. Engines with huge cams, often have very little at idle. Its what the needle does thats important.

[Michael]

If it is constantly steady @ 21 do not touch it. If it is constant period leave it alone. You are on the money. Mine was 16 prior to that. With tunning with the guage it is 21 steady now.

[joe]

You're doing fine David, don't mess with it smile.gif

[David Simon]

Thanks guys, that's what I needed to hear. So, what am I going to do with this guage now? I guess I can check the fuel pressure since it does that too.

[Sgt. Dave]

7" at idle will put you into the Vac advance curve. Check your total timing #s, make sure you don't have too much advance. What idle speed you running?

[Tubro]

Well its really useful when everything is not going well. I know mechanics that can hook up a gauge and be like "Number 2 cyl, exhaust valve cam lobe is worn bout 3/16s of an inch off." Well not really, but almost.

[Tubro]

Oh hey David, I forgot to ask. Have any kids? Well you can let them entertain themselves buy sitting around sucking on the gauge, or did I only do that as a kid. And when they get bored of that the can use your dwell meter (if you have a vaccume gauge, you HAVE to have an old school dwell meter) to play Ghostbusters with, cause it looks like the little PK meter on the movie. Oh and they can shoot each other with the timing light. I had a big heavy steel chrome one. Oh and you can give em a dist cap and plugwires, they can put it on thier head while the watch "Electric Avenue" video. Remember that, dude looked like bob marley, you know plug wires, dreadlocks, well I was a wierd child.

[David Simon]

Sgt. Dave, I don't know what the idle is, no tach, I just set it where it sounds good. I have the timing set at 12.

Tubro, I know a few old guys like that, can look at a picture of a car in a magazine and tell you the timing is 2 degrees off. ;)I have one daughter, but she's only 12 days old so it will be a little while before her mom will let me hook a vacuum guage to her. I have a big chrome timing light from Sear's, it's 20 years old and still works like a champ and still in the original box.