<VV> Carter YH pump squirt

[Craig Nicol]

Doug asked:

Turbo guys! 

I am used to the behavior of the accelerator pumps on the Rochester carbs.
Take the air cleaner off, pull the throttle, should get an easily visible
squirt, and also hear that "psst" noise.

Am I correct that I should get the same from the Carter YH (air cleaner
housing removed, peering into the end with flashlight). When I checked
Leigh's carb tonight, I couldn't see or hear any evidence that it is
working. Is it especially difficult to detect, or is mine not working?

Thanks!

-- Doug Mackintosh

 

Craig replies:

No, you won't see a squirt on a YH, AFIK.  The pump is pulled down by engine
vacuum. It remains down during normal driving, cocked and ready to go. When
the engine vacuum goes away (think acceleration), two things happen. 1) The
choke plate "blinks" when vacuum goes away at the choke pull-off and 2) With
the vacuum gone, the spring that pushes up on the accel pump piston can
operate and it causes fuel loaded into the pump to discharge (squirt).
There is no mechanical connection between the accel pump and the throttle.
With the engine off (no vacuum) pumping the throttle all day will have no
affect on the pump. With the engine running and the right mirror, you may be
able to see the pump squirt, but I've never tried and the choke plate
"blink" may complicate the sight path.

 

Craig Nicol