[1968KR]

Is it possible to get too much fuel to the secondaries of my carb? My motor is being overwhelmed under hard acceleration, causing the car to hesitate. I am finding black smoke in the back of the carb. I checked the float level and it seems to be adjusted properly, just below the sight plug.

 

[DaveK]

Are you using a mechanical or vacuum secondaries carb?

 

[sharkmouth]

You may want to look at holley's downloadable carb calibration list and reset your holley to factory specs....and start over with tuning.

http://www.holley.com/HiOctn/ProdLine/CarbList.pdf

right click on this link and save it to your pc....good resource for calibration ideas!!
you'll need the adobe acrobat reader to read it

 

[1968KR]

Vacuum secondaries, it's the stock 4150, list 4168 Holley 735cfm

 

[camachinist]

As a baseline, have someone observe the tailpipe emissions while you attempt to duplicate the condition. Note any unusual emissions.

Then, disconnect the vacuum pod accuator rod from the throttle shaft and re-try. I would recommend securing the shaft to remain closed for safety...it shouldn't roll over but, on a big engine, you never know.

Instinct is accelerator pump circuit... secondary possibility is G-induced lean-out from fuel level in secondaries uncovering jets. Especially problematical in applications like my race car which have fairly high G loads upon initial acceleration.

Lastly, due to same condition, primary metering can change due to fuel level interfering with vent flow...

Get back to us with some more observations...