Vaccum reading in 5th gear cruising?

davec73

SCCoA Member
What should the vaccum reading be in 5th gear on the highway cruising at about 70? Mine is 18 - 20 and it is still running a little rough. I sprayed carb and choke all around the engine bay and didnt get any variance in the idle either way but it does it intermitantly, any help is greatly appreciated.
David
 
Mine is closer to 10" I think. Depends if you are going slight uphill or downhill. Doesn't make sense it would be that high if you're on the gas a little bit.. when you open the throttle it should always go lower. All I can think is maybe the air filter is clogged.
 
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What should the vaccum reading be in 5th gear on the highway cruising at about 70? Mine is 18 - 20 and it is still running a little rough. I sprayed carb and choke all around the engine bay and didnt get any variance in the idle either way but it does it intermitantly, any help is greatly appreciated.
David

Spraying carb cleaner or ether or anything like that will not find you anything and is a waste of time. The only way to find vacuum leaks is with a smoke test.

18-20" vacuum is very good for idle but not applicable to 70mph cruise unless you are coasting which is misleading. Cruising on level ground with a good running stock SC will net about 12-13" of vacuum.
 
Spraying carb cleaner or ether or anything like that will not find you anything and is a waste of time. The only way to find vacuum leaks is with a smoke test.

18-20" vacuum is very good for idle but not applicable to 70mph cruise unless you are coasting which is misleading. Cruising on level ground with a good running stock SC will net about 12-13" of vacuum.

Thats great but what other than a clogged air filter could cause this issue? I am going to start there but but ive never really dealt with having too much vaccum lol
 
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