I have an idea, put a NASCAR restrictor plate under the carb. 
 Kidding!
							
						
					
 Kidding!
							
						
 Kidding!
							
						
  One of my most favorite motors was a 283 with a steel crank, pistons, etc, Z28 intake and a holley 650 vac secondary. The way it would wind out, I didn't miss a DP. Besides, it gave me better mileage too.  Ironically, the street setup I had on my Pro-Street/Strip car used two 600 vacuum secondaries on a offenhauser low rise twin four barrel manifold, 468 cube big block chevy. The street manners were for the day, awesome.  It actually rivaled modern fuel injection when it was within a certain temperature range, 
  
 
							
						


  I would swap the carb with my holley for track duty and all was well.  Actually put a few thousand street miles on that carb and ultimately had it on a car that I traded in.  I would have loved to see the look on some tech's face when he discovered why the secondaries wouldn't open. 
							
						


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