Small jet in vacuum advance line in 81 Interstate

When I pulled off the vacuum advance hose, there was a hard bump in it. When I cut the hose open, I found someone had installed a tiny brass jet in the line which was very restrictive. Is this stock, or someone's modification? :?

Hmm, never heard of it having a restrictor nor seen in any parts fiche. Take that sucker out!

wow its hard to figure this one :headscratch: maybe some one can make sense of this :mrgreen:

A prior owner probably stuck it in there to cut the advance back.
Maybe it was pinging on regular gas and they were trying to prevent that but pinging could also be caused by running lean caused by dirty jets.
Let us know how it runs after removing the restriction and clean carbs.

That would slow down the application and release of the advance mechanism...that's all it would do. We used to do that on the vacuum line for the transmission modulator valve to keep them from "shuttle" shifting. We would take a glass fuse, bust the glass, and then drill a tiny hole in the metal end of the fuse. Then we'd stick that in the vac line as a restrictor.
Don't have a clue why anyone would want one in a vac. advance line, unless the bike was just too powerful for them at take-off... :smilie_happy:

However...now that I think of it, the reason we did it was because the car usually had burnt/mis-adjusted valves, and the vacuum signal would just be bouncing it's butt off on a gauge. The restrictor would calm the pulses down.

id say joel has it on reason....... :mrgreen:

Many vacuum advance distributor set ups on cars had vacuum delay valves. This was a metered oriface to delay the operation of the vacuum advance. This was for Nox emissions reduction on cars, but I'd suspect the previous wing owner was attempting to deal with a detonation problem by slowing the rate of accumulated vacuum to the advance mechanism. I suppose it could help? Remove it and see what happens. You might not need it.

My '82 Standard has a "pinging" problem in warmer weather running on regular gas. Premium gas pretty much takes care of it for me. And for a 4 gallon fill up, what more could it cost? about 50 cents, max?

scdmarx":1sadg0gn said:

My '82 Standard has a "pinging" problem in warmer weather running on regular gas. Premium gas pretty much takes care of it for me. And for a 4 gallon fill up, what more could it cost? about 50 cents, max?

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Wow...pinging! I haven't heard engine pinging in years! BTW, I use 87 octane without any pinging, could be something else amiss?

mcgovern61":3hcrjwem said:

could be something else amiss?

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Absolutely. Still gotta pull the motor out, I'll check it out then. I think our state has the worst gas in the country, but somehow I get the feeling the problem is besides that. However, a little premium gas seems to cover a multitude of "amiss".