if an engine has low vacuum, is it possible that it will it not open the secondaries all the way?
vacuum secondaries question
curley8788
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if an engine has low vacuum, is it possible that it will it not open the secondaries all the way?
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The vacuum that operates the secondaries isn't produced in the manifold, but in the venturi of one of the primaries.
Look on page 6 of this Holley manual:
http://www.holley.com/data/TechService/Technical/Carburetor Tech Info.pdf
Look on page 6 of this Holley manual:
http://www.holley.com/data/TechService/Technical/Carburetor Tech Info.pdf
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On a VS carb, there is a spring that determines how quickly (or if) it opens. As said above, not dependent upon engine vacuum - but it is very possible the secondaries are not opening fully.
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i know all too well about those springs...ive been changing them and playing with the check ball for weeks now to no avail.
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I hate to even suggest it and I`ve never done this before but I`ve seen VS carbs that someone had put a screw in the linkage so that it opened the secondarys mechanicaly instead of tuning it correctly. Again, it`s not something I would do but you could try it and see what happens.
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Good point - check the screws on the bottom of the carb holding the baseplate to the main housing as well. I'm not sure of all the circuitry, but you might have something else going on that's affecting it.
Was it a new carb? Rebuilt? Unknown history?
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rebuilt carb. it has all the gaskets and the diaphram is perfect. the carb looks great inside and out. im totally mind boggled when it comes to the lack of performance of this car.
Mike..are you familiar with the paper clip test?A micro switch would be better..but it is an old school technique that works.With the engine shut off,place a paper clip on the vac sec link tight to the bottom of the dashpot.As the secondary rod lifts on a full power run,the rod will slip thru the paper clip and then return to closed.Shut off the engine and then manually open the secondarys until the paper clip again contacts the dashpot.You can now view down the throttle bore and see how far your secondary blades rolled open.Hope this helps.
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Mike, you got any money for a carb? I saw a bunch on ebay for under $100. you`ll need to rebuid but you can sell your vs carb to offset the price.
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yep. im going to try that once i get the carb back together.
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