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Autolite 4100 - Secondaries Not Opening?

I'm looking for the procedure to check and see if the secondaries are opening on my autolite 4100. I'm suspicious that they aren't because when I examine the carb, I notice that the butterflys for the primaries are smooth and clean, while the ones for the secondaries are not - like there's no air/fuel flowing past them and they've been sitting closed forever. Also, I don't see them open when I look down the carb and rev up the engine in park. Should I be able to see them open, or would they only open under a load? I know they aren't frozen because I can open them manually by moving the part (whatever it's called) near the secondary diaphram. Maybe the diaphram is bad or not adjusted right? I just had the carb rebuilt by a reputable (as far as I know) local carb service place. I'll probably end up going back there, but I wanted to check it on my own first so I know what's going on.

If it maters, this carb is on a 66 289 daily driver. I've just added a new cam, and that's when I really started looking at the carb. The engine idles and runs fine. I just wonder if I'm not getting the acceleration I should be getting.

Thanks for your help, Mike

Reply to
Michael
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You will never get a vacuum secondary to open by reving the engine with no load. The primaries will flow enough air (under no load) to let the engine rev to self destruction. The secondaries are only going to open when the primaries can no longer supply adequate air flow for the engine

Reply to
Jimz466

You could try blocking/taping/jamming the secondaries/linkage closed so they can't open, then go for a little test drive and remove your modifications and try again. If you notice a difference in power and sound then they work. Just a thought. You could also have a buddy (trust is important here

*snicker*) sit on the fender and you can nail it down the street real quick while he watches the secondaries. Again, just a thought. ;)
Reply to
Cory Dunkle

Michael opined in news: snipped-for-privacy@posting.google.com:

  1. Take off air cleaner and drive it... moderate accel then WOT..

- If they're woking you can tell by the sound as they opn.

  1. DONT REV AN AT CAR IN PARK!!!!!!!!!!
Reply to
Backyard Mechanic

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