My local machine shop guy says that double pumpers pump excess gas in the engine during normal driving if the roads are bumpy, washing the cylinders and causing
oil dilution, etc,etc. I took off the double pumper and went to vacum secondaries, but lost a ton of instant response and midrange (went from 650 to 750). Was wondering how double pumpers are working for other guys in Cobras that are stiffly sprung--I think he's full of baloney. Am going to rejet the double pumper and try it,as it was way too rich before. Holly tech man recommends a 650 double pumper with mechanical secondaries. Obviously both carbs could be dialed in, but, are double pumpers as a category bad on less than perfect roads? Thanks, fantastic forum.