Vacuum gauge reading with a Model B distributor

[Ian in Mississauga]

I always hook up a vacuum gauge at the start of the season as a diagnostic tool. With a model A distributor I get a range of about 16" to 20". Recently I installed a model B distributor. What numbers are normal with this set up?
tia, Ian

[Patrick L.]

I don't see where there should be a difference. We're talking about engine condition not ignition system. The base timing is advanced more than an A, thats all.

[michael a]

I always set my distributor at the highest point of vacuum this is an FSI unit with flyweight advanced positive High Point at idle

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[SeaSlugs]

http://www.onallcylinders.com/wp-con...-reading-1.png

invaluable tool. Between a compression tester, leakdown tester, and a vacuum gauge you can tell everything there is to know about any engine and anytime a suspected engine issue, backfiring, overheating, or low power these 3 basic tests should be run. Easily do all 3 in less than an hour.

Link is a great chart you can print off and pin to the garage wall or wrap the vacuum gauge in it.

Model A has an easy access vacuum port right on the manifold so it cant get any easier.

[Corley]

Originally Posted by michael a

I always set my distributor at the highest point of vacuum this is an FSI unit with flyweight advanced positive High Point at idle

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Huh? "Splain yourself Lucy?"

[100IH]

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Comparing distributors is, to me a fuzzy thing because the A with the manual advance will be all over the map for vacuum depending where basic is set and where lever is set. B same thing for basic timing and except for all of the variables in camshaft profile, timing covers and A vs. B block variables and condition of centrifugal timing on B dist. Like comparing track shoes to horse shoes.
I commend your use of the vacuum gauge though.

[michael a]

Originally Posted by Corley

Huh? "Splain yourself Lucy?"

Have you ever used the vacuum gauge

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[Corley]

Originally Posted by michael a

Have you ever used the vacuum gauge

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Only for the last 60 years or so. (I'm 78 now, been wrenching most of those years.) However, your sentence did not make sense to me. Positive? What's that about??? I've never found highest vacuum reading to be the optimal timing set point. In fact on many engines, timing and vacuum readings are not really related at all, unless timing is way out.

Being a Jr member here does not imply one is new to As or mechanics, only that one tends to not post much.