i've got a 73 RX-2 with an engine from a 80 RX-7 in it. I'm using a ported out 84-85 intake manifold and the original 73 carb (for simplicities sake and ease of connecting the various cables/linkages). All emission valves are removed, and openings are blocked off with plates.

My carb is jetted per Racing Beat specs for the original engine - 90/150. My Haynes manual for RX-7 says that my year of engine should be have the carb jetted at 93/160.

At 3000 RPM in 2nd or 3rd gear I get a constant surge. I *think* it's a lean surge. I'm pretty sure that at 3000 RPM I'm on the primary circuit, so if it is a lean surge, it's probably because I'm jetted 90 instead of 93.

Any thoughts on this?

Other differences between the carbs are:
primary main air bleed: 1980=90, 1973=80
secondary main air bleed: 1980=140, 1973=160
primary slow jet: 1980=46, 1973=50
secondary slow jet: 1980=120, 1973=130
Primary Slow Air Bleed: 1980=70/150, 1973=70/210
Secondary Slow Air bleed: 1980=160/60, 1973=100/60

So basically, the 1973 carb is a much leaner carb than one for 79-85 engines. I have a 1980 carb available - should I just take all the jets and airbleeds from it and install them in the 73 carb so the mixture is better suited to the better flowing engine?

thanks in advance.