Old dog, new trick?

pamcopete

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Well, the old dog part is right. Not sure about the new trick. It's new to me!

I used my shop vac to test the vacuum slides on my carbs. Just hold the vacuum hose on the cylinder side of the carb and open the throttle. The slide will open up proving that there are no holes and no binding and no flutter.

CAUTION: MAKE SURE THAT THERE IS NO FUEL IN THE CARB BOWL AND THAT THE CARB IS COMPLETELY DRY OF FUEL.
 
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I cant remember how many atmospheres a shop vac pulls at, but im sure its far stronger than our little325cc cylinders pull.
I wouldn't do it. Thumb test shows fine.
pulling that much air thru could mask a very large hole. Im surprised the pull didn't just cock the slide in the hole, preventing lift.
 
angus67,

A more important consideration is this:

CAUTION: MAKE SURE THAT THERE IS NO FUEL IN THE CARB BOWL AND THAT THE CARB IS COMPLETELY DRY OF FUEL.
 
Sounds like someone one has parts of a vacuum cleaner scattered around the yard.
 
Angus ever stuck your hand over the carb of a running motor? You will be impressed how much vacuum 325cc can create! An old clear the jets trick :wink2: We used to do that with V8s.
 
Yes, a vacuum cleaner can pull a lot of CFMs, but not much vacuum before the centrifugal vanes begin to stall. So, it's safe on the carb. A positive displacement piston/cylinder can pull a lot more vacuum, which puts more stress on the throttling components...
 
Angus ever stuck your hand over the carb of a running motor? You will be impressed how much vacuum 325cc can create! An old clear the jets trick :wink2: We used to do that with V8s.
What do you mean "used to". ? I do that to my 67 fairlane all the time
 
Youre all Woodheads...:doh: ?

No Vacuumpump ...all over the World(!!!) can't create a load over -0,99 Atmospheres.
One 4stroke Piston .325cc pull's ~1600liter / 400 Gal. Air in 1 Minute(!) at 10ooo Rev. (0,325liter x 5000 = 1625 liter) Don't worry about the Carbs!
In the End the Slide also move if you blow pressAir in the right direction into the Carb. with open Throttle!

I still also synchrone the Carbs with the Vacuumcleaner on the Workbench bevor i reinstall them. Because all mecanical motorfoults are had no influence then.

If the Carbs installed and now are any differnces: it must came from the Valves ore the Pistons ...

Think about!
Heri :bike:
 
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CAUTION: MAKE SURE THAT THERE IS NO FUEL IN THE CARB BOWL AND THAT THE CARB IS COMPLETELY DRY OF FUEL.

Reminds me of a time where a friends sister wanted fuel for her car from her parents car using a shop vac. Didn't turn out so well. She did live.
 
That is true, i allways did it after reinstallation, so i don‘t think about such possibility of stupidness
But it should be clear and i thank for your advise!

Greetz heri
 
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