| dggohl | -- 05-15-2019 @ 6:05 PM |
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I have a 53 Merc 255, and I'm preforming a vacuum test of the intake. I'm reading 19. I can't find the right spec on where it should be. I was told around 25. If that's the case is there a way to increase the vacuum to normal specs?
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| 40cpe | -- 05-15-2019 @ 6:21 PM |
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Vacuum reading is an indication of the mechanical condition and tune of the engine. IMO 19 is a very good reading for a flathead if the needle is steady. If the needle is not steady, there are charts to assist in diagnosing what might be causing the unsteady reading.
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| TomO | -- 05-16-2019 @ 6:33 AM |
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Here is an explanation of engine vacuum and how to read a vacuum gauge: http://www.secondchancegarage.com/public/186.cfm When you take your readings, disconnect and plug the vacuum line to the dual diaphragm fuel pump, to prevent false readings. Tom
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| 37RAGTOPMAN | -- 05-24-2019 @ 9:09 AM |
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HI you might be able to increase the amount of vacuum, by adjusting the air mixture screws on the carb, screw them in slowing one at a time and see it the gauge goes up too far it it will stall, to far out will run rich, also you can adjust the timing to see if that might increase the vacuum. mark the distributor, then loosen it up and turn one way the other and see if you get a different reading, also and use a timing light to see if the timing is correct on the factory marks, you might be able fine tune it, a steady reading is what you want, a good vacuum gauge has the instructions on it, telling you if your timing is off , also bad valves, air leaks, my 2 cents, 37RAGTOPMAN
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