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I have always wondered and can't seem to tell from operation when the secondary bores of my Holley carb is supposed to "engage"?? I have heard in the past that they only function and wide open throttle, and I have also heard that they can be inoperative and most people can't tell the difference. I understand that they are supposed to open based on vacuum, but from a practical standpoint when do they come in to play and in what conditions? My car is a 67 327/33hp car with factory type throttle components.
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Re: Carb secondary operation - when?
should come in at 3000 or so rpm full throttle application. You should be able to hear them open. You can remove the vacuum pod from the carb and check it's operation with a vacuum pump.Bill Clupper #618 -
Re: Carb secondary operation - when?
should come in at 3000 or so rpm full throttle application. You should be able to hear them open. You can remove the vacuum pod from the carb and check it's operation with a vacuum pump.Bill Clupper #618Comment
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Re: Carb secondary operation - when?
if you look at the secondary side linkage you will see a built in stop that hits the aluminum throttle body base plate to limit the secondary at wide open throttle. but a dob of grease on the baseplate where this stop hit at WOT and go for a full throttle run,come back and look at the grease spot for a mark thar shows it went wide open.Comment
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Re: Carb secondary operation - when?
if you look at the secondary side linkage you will see a built in stop that hits the aluminum throttle body base plate to limit the secondary at wide open throttle. but a dob of grease on the baseplate where this stop hit at WOT and go for a full throttle run,come back and look at the grease spot for a mark thar shows it went wide open.Comment
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Re: Carb secondary operation - when?
Tim,
I've always used a telltale to indicate when and how far yhe secondary throttle shaft opens. I use a wire twist ( like from a loaf of bread, baggies ) and wrap it equal length around the secondary throttle shaft on the drivers side and twist it all the way to the end tight enough so the when the shaft turns it will move without taking the twist with it but when the throttle returns the twist will go along for the ride. The starting point for test is with the twisted end forward touching the throttle body. If after a full throttle to redline run it ends up straight up they opened all the way. Anything in between indicates partial opening which you can visually check after your test by opening throttles by hand with motor shut down until the end of the twist touches the throttle body You can also check when they open by hitting full throttle after launch and running up to a certain rpm and check to see if the telltale moved. If this sounds a little confusing e-mail me with a FAX number and I'll draw a picture of what the setup looks like.
WayneComment
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Re: Carb secondary operation - when?
Tim,
I've always used a telltale to indicate when and how far yhe secondary throttle shaft opens. I use a wire twist ( like from a loaf of bread, baggies ) and wrap it equal length around the secondary throttle shaft on the drivers side and twist it all the way to the end tight enough so the when the shaft turns it will move without taking the twist with it but when the throttle returns the twist will go along for the ride. The starting point for test is with the twisted end forward touching the throttle body. If after a full throttle to redline run it ends up straight up they opened all the way. Anything in between indicates partial opening which you can visually check after your test by opening throttles by hand with motor shut down until the end of the twist touches the throttle body You can also check when they open by hitting full throttle after launch and running up to a certain rpm and check to see if the telltale moved. If this sounds a little confusing e-mail me with a FAX number and I'll draw a picture of what the setup looks like.
WayneComment
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