It's a 4160 because of the vacuum secondary. You can buy this carb from Summit for $250. Although it doesn't have the milled choke tower or the pretty power coat.

4150--Two metering blocks
4160-- One metering block and rear metering plate.

Either Vac or Mech secondaries.;)

Good to know. So 4160 is always vacuum secondary but 4150 can be either vacuum or mechanical?

The main difference was (IMHO) the air bleeds and the LSA of the cam. His carb was a Holley 750 and mine is a Mighty Demon 750. The Mighty Demon is modeled after a Holley double, but Demons are notoriously lean out of the box.

Also, the throttle pump cams and squirter nozzles were waaay too small on the Demon. Which I think is a result of my LSA, I had the same duration as the other dude.



Another vote here for mechanical, vacuum sucks.

No, 4160s or 4150s can be either Vac or Mech secondaries. It has to to do with the metering blocks.:D

E85
 

August 2008 Chevy High-Performance Mag-- Page 44


Easy E85 --Installing Quick Fuel Technology's Billet Metering Block Conversion Kit. They installed it on a Holley 750 DP. Good Stuff.


I have the mag if you want it.:thumbs_up:

I found this on FordMuscle.com after I found out what I thought was wrong.

"When it comes to Holleys, 4150 and 4160 refer to the two most popular models of Holley carbs. A 4150 has both primary and secondary metering blocks, allowing you to change jetting for both the primary and secondary circuits. The 4160 models utilize a metering plate in the secondary , which has fixed, non-adjustable, metering orifices. All 4160 models have vacuum actuated secondary throttle plates. The 4150 models come in either dual mechanical throttle plates or with vacuum secondaries. All 4150's have dual accelerator pumps, and dual fuel inlets hence the term "double pumper." The difference between vacuum and mechanical secondaries is simply in how the carb actuates the secondary metering system. In vacuum actuated carbs, the secondaries open up only when the vacuum across the primary venturis reaches a certain level. A diaphragm housing on the side of the carb contains a changeable spring which controls precisely when the secondaries open. On a mechanical secondary carb the secondaries open when the throttle lever reaches a certain position. The simplest way to tell which type you have is to look down the throat of the carb, with the engine off, and pull back on the throttle lever. If the secondaries open, its a mechanical secondary."

Here's the artical online. http://www.chevyhiperformance.com/te...kit/index.html

Now I see what you mean. Yea, if you look at it that way 4160 would all be Vac Secondaries. But, 4150 and 4160 is determined by metering blocks--the Vac Secondary thing is just a by line. But, could be true if you want to look at it as a Vac Secondary only.:thumbs_up:

So I can toss the Mag??????????