| carcrazy | -- 03-19-2013 @ 4:04 PM |
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I have a V8-60 engine which runs great but produces fluctuating vacuum readings. The only two vacuum tap sources available on this engine are: the one between cylinders #5 & #6 (for the distributor signal) and between cylinders #7 & #8 (the windshield wiper motor vacuum source). Since each of these taps only senses two cylinders, a fluctuating vacuum reading is produced. Would a restrictor placed in the vacuum line provide a steady vacuum source with a healthy running engine? What would be a good size orifice to use? Thank you for any suggestions.
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| shogun1940 | -- 03-19-2013 @ 5:02 PM |
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how about a plate right under the carb, 1/4 outlet should be good.
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| 40 Coupe | -- 03-20-2013 @ 4:39 AM |
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The reading should be steady without any modifications to the engine or the gauge, connect to the port between 7 & 8. You can remove the rubber vacuum wiper hose and connect your gauge. If the reading is not steady, first look at your gauge. They sometimes have a small orifice at the hoes end and the orifice can come out so try it on another car to make sure it will give a steady reading. If the gauge is good and the reading unstable on your car note between what readings the gauge fluctuates, say 10-15, 12-17,5-20 and note if the reading is floating or jumping. Then look at a chart for vacuum reading, this will tell you what areas to look at. You can find the charts on the web. This message was edited by 40 Coupe on 3-20-13 @ 4:41 AM
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| supereal | -- 03-20-2013 @ 7:42 AM |
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If you need a vacuum chart, I will post one. Vacuum is rarely steady, in any case, but large variations indicate problems. You can connect anywhere on the intake manifold. Most use the wiper tap, but before the backfire valve, if you have one in the hose.
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| Old Henry | -- 03-20-2013 @ 7:21 PM |
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Here is a site that can be very helpful in interpreting vacuum gauge readings. Scroll to the bottom of the page and click on the green buttons for various animations of gauges showing different conditions. http://www.secondchancegarage.com/public/186.cfm Old Henry (The older I get, the better old looks.)
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