Vacume advance

[socor7]

While working on my 76 tonight I found a steel ball in the vacume advance hose. Is there any reason that some one would block the vacume advance to the Distributor?

 

[JohnZ]

While working on my 76 tonight I found a steel ball in the vacume advance hose. Is there any reason that some one would block the vacume advance to the Distributor?

Yes! Whoever did that had no clue whatsoever about what vacuum advance is, why it's there, what it does (and doesn't do), and how it works. OR, the diaphragm failed in the vacuum advance can and they stuck the ball in there to stop the vacuum leak instead of fixing it. :eyerole

 

[76ers]

Shade Tree Special

While working on my 76 tonight I found a steel ball in the vacume advance hose. Is there any reason that some one would block the vacume advance to the Distributor?

In my younger years as an actual mechanic, I found BBs all the time in Vac Advances. It was a common cure for a vacuum leak, though the owners had no clue they were screwing up the way the car ran.

 

[socor7]

What is the bests way to check for a vacume leak in the diaphram of the distributor?

Thanks

Drew

 

[vette-dude]

Light a cigarette and blow smoke through the line leading to the cannister. If smoke comes out the dist side, the diaphram is bad. Of course the non-smokers will tell you it will give you cancer and the heart association will tell you you are going to die from a heart attack but what the hey, it works, it's cheap and it's a postitive visual thing.

Randy

 

[JohnZ]

What is the bests way to check for a vacume leak in the diaphram of the distributor?

Thanks

Drew

Remove the cap so you can see the breaker plate and rod from the vacuum advance can that moves it, and use a MityVac to apply vacuum to the can; pump it up so the can has moved full stroke and pinch the hose shut where it connects to the can. The rod and plate shouldn't move at all until you disconnect the hose or release the vacuum at the MityVac.

 

[socor7]

That is exactly what I did and it held, so I am still puzzeled why some one would block the Vac advance. What is the best way to test for full advance at 6000 rpm.

mechanical initial and vacume?

I want to make sure that the advance curve is correct. As I am not sure if the mechanical advance what changed for any reason (previous owner)


Thanks,

Drew

 

[gary55r]

I found a BB in the vacume line going to the EGR Valve on my 77. My guess it was a Bubba fix for a faulty EGR Valve or an attempt to prevent the smog controls from working. I removed it and didn't notice any difference.

Gary

 

[Bob Chadwick]

There is no need to check for advance at 6000 RPM. The distributor should be adjusted so that the mechanical advance is all in at 3000 RPM. The vacuum advance, assuming yours is connected to the port that has vacuum at idle can be checked at very low rpm's.