Guest tony78_280z Posted July 16, 2004 Share Posted July 16, 2004 I'm almost positive my engine bogging at take off is due to poor vacuum advance. How do I check it without replacing the dizzy? Quote Link to comment Share on other sites More sharing options...
Miles Posted July 17, 2004 Share Posted July 17, 2004 For a stock 72 SBC with a points style distributor: I hooked up a hand vacume pump to the hose that goes to the vacume advance. I pumped up the vacume and watched for the plate that the points are attached to move. It didn't move. I also noticed that the plate was loose and wobbled around. I checked the timing with a timing light. The timing jumped around due to the plate being loose. I replaced the worn distributor with a rebuiilt unit which also included a new vacume advance. Now the engine runs smooth, starts easy and has better throttle response. Miles Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted July 17, 2004 Share Posted July 17, 2004 Sorry, double posted. Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted July 17, 2004 Share Posted July 17, 2004 If you aren't afraid of getting 'car cooties' you can just suck on the hose to the vacuum unit on the distributor... If it won't hold a vacuum against your tongue, the diaphragm is bad. If you take the cap off the distributor and repeat the procedure, you should see the breaker plate move. PS- This looks like a generic "ignition and electrical" type question. FYI: The mechanical advance could be stuck and cause your bog, but the vacuum advance is there for fuel economy, and doesn't do much if anything at WOT (very little vacuum). Quote Link to comment Share on other sites More sharing options...
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