[6pack] dropping idle

[Colin Thom]

Hi Gang,

 

All is well when I first bring the engine down to idle from speed, but it
will only hold a nice 800-ish idle for a few seconds before dropping to
5-600 rpm and starting to sound like it's gonna croak. All I've done
recently is change the fuel filter. I did notice when I did that, that the
new filter wasn't holding fuel at first but now it seems OK. When I
installed the new filter, I did operate the fuel pump primer manually and
noticed that I wasn't able to fill the filter with fuel. Knowing that the
carbs were full and the engine warm, I just started the engine and it was
fine.  The engine runs fine.the car goes like hell. It just doesn't idle
right and this is a new thing. All air hose connections are tight, there's
oil in the dashpots, K&N air cleaners are freshly cleaned. Carbs are
synchronized. Throttle response is excellent and mixture is OK. Cam has a
slightly warmed up "street" profile, hence preferred idle speed of 800-900.
One day it was all sweet but a fuel filter change later, it ain't.  Any
ideas? Might I have a failing fuel pump that is assisted somehow by high
engine rpm so I only see a problem at idle? 

 

Thanks for all suggestions,

 

Colin '75