secondaries

[mopardads67]

I have a holley 4160 ,and last night while I was checking wide open throttle with the car off for kick down adjustments I noticed that my secondaries did not open.So I thought "well they are vacuum opperated so start the car and actualy see".They did not even start to open until 6grand.I figure I need a lighter spring but what is a good rpm for them to open?Thanks for any input Mark.

 

[1968FormulaS340]

You can't check the secondary operation on a vacuum secondary carb by hand revving it and looking down the carb.

 

[RustyRatRod]

The car must be under a load. Get a paper clip and attach it to the secondary diaphragm rod right up against the bottom of the diaphragm housing. Go drive the car and fling her wide open a few times. Come back and take note of how far down the paper clip is. That's a good indicator of how much the secondaries open. Also remember this, if you can FEEL the secondaries open on a VC carburetor, you're not going as fast as you could. The transition should be clean and unidentifiable. You should feel linear acelleration.

 

[mopardads67]

Thanks guys.Learn somthing everyday