Have you disconnected your OSAC system?

Yes, but only do it if you want your car to stop running as if its shoelaces are tied together. Don't do it if you like hesitation and mushy acceleration, because you'll be disappointed with the results.



Yep, do not pass go/do not collect $200.



Not even a little bit.



It's a purely academic exercise. This system—OSAC stands for Orifice Spark Advance Control—was a cheap and nasty means of squeaking the cars past 1974 emissions standards so they'd be legal to offer for sale. The system delays vacuum to the distributor by a set number of seconds to reduce spark advance during acceleration, eventually letting vacuum through to allow spark advance during cruise. This lessens NOx emissions while severely degrading driveability (meanwhile, the EGR valve is in on both parts of that game, too).
Thanks for weighing in, Dan. I got rid of the EGR system on my engine a long time ago. Sounds like I just need to connect the vacuum line on the distributor directly to the vacuum nipple on the base of the carb (stock Holley 1945), bypassing the OSAC valve on the air cleaner. That way, the distributor's vacuum advance will continue to operate. Sounds like my engine will run better, altho it runs really well right now. I haven't noticed the mushy acceleration that you referred to, BTW. I just wanted to make sure I didn't royally screw up anything with my engine before I try this. Thanks! CRUISER