Since Mr Ken Crocie brought up the 8156 Double Pumper Carb in a post, I will add some additional info on that carb.
Here is a Link to the #8156 750 CFM Double Pumper Carb.
A Post by "Tuner" (He goes by Yeti) on the Yellow Bullet Forums)
http://www.yellowbullet.com/forum/sh....php?t=1321578
"The 8156 came out in 1978 and is essentially a 4779 double pumper with four corner idle. It was the first four-corner-idle double pumper Holley produced. Original jet size is 70P & 83S. Should work OK on a T-Ram."
This link shows a nice picture of the Johnson Linkage
https://books.google.com/books?id=_f...s-8156&f=false
The carb was a 750 CFM carb as mentioned by several people. It used a 70 Primary Jet and a 83 Secondary jet. It used a 6.5 Power Valve on the Primary side of the carb. It had 4 corner Idle, (IT WAS THE VERY FIRST 4 CORNER IDLE HOLLEY CARB, I worked on that carb in 1977). It used a .028 Pump Shooter on the Primary and a .031 Pump Shooter on the Secondary. It had the normal 1-3/8" Primary & Secondary Venturis and the normal 1-11/16" Throttle Blade Base Plate.
The 850 CFM version of the carb was List #8162.
You can see the Johnson Linkage and how the linkage was much more complicated with the cam slot mounted on the primary lever (with a horizontal slot vs the 660 center squirters vertical slot), the pivot/roller on the main body, the link from the pivot to the secondary throttle lever, the cut off airhorn (production) and the 50cc Pump system sometimes installed on the Primary side of the carb, like a 660 center squirter carb. The pic shows the small pump.
The carb had a normal Power Valve on the front and a blocked PV on the Secondary block.
The front metering block number is 8542A, the Rear Metering Block is 6541A. The base is 12R-112-32.
Tom V.