DeTomaso Mailing List: May 2001, Message #29

When I purchased my Pantera it had the original 4300D Motorcraft.
It did not have any lag.  The carb doesn't require a secondary 
accelerator pump due to it's air valve secondary design.  I'd 
wager that the majority of Holleys on Panteras do not have 
secondary accelerator pumps, either.  Usually, only the mechanical 
secondary versions are double pumpers.  Have you checked the 
primary accelerator pump to see if it's working.  Also, the secondary 
opening point may not correct.  IIRC, only the early model 4300's have 
adjustable secondary air valve.  The adjustment procedure is:

1. Loosen clamp screw and let housing rotate to no load position.
2. Hold air valve in closed position.
3. Scribe reference mark.  
4. Rotate nylon spring housing counter-clockwise the proper number 
   of knobs and then tighten screw.  The proper number of knobs is 
   defined in the shop manual.

The previous owner had the 4300D rebuilt before I purchased the car 
because there was hesitation and it generally didn't run very well.
After I bought the car, I traced the problem to an improperly set up
dual point distributor.  

Dan Jones


Current question deals with a predictable "lag" when you stomp on the 
accelerator.  Current set up is bone stock Motorcraft.  Is this why so many 
people convert over to Holly where there is a secondary pumper that will
keep 
up?  I hate to keep messing with this original survivor, but I am starting
to 
understand why so many of these cars are modified.