Ok, I just tried putting a Holley 1909 onto my 144. The engine ran fine, carb working fine. I tinkered for a while to fashion a hot air choke tube, then screwed it on. Then when I restarted the engine, for no apparent reason, vacuum started sucking through the automatic choke! I haven't taken it apart yet, but what the heck is going on when your auto choke housing (with the spring)) is sucking vacuum?!!