3 replies to this topic

[G-Man]

Been lurking on this forum and appreciate the expertise here...

I need some help jetting the stock Nikki carb on my 1985 12A IT-A Rx-7, please. And I hope this research will be helpful to others.

Please note - I race in Colorado at about 5,000 feet above sea level. About 18% less oxygen at this altitude and summer trackside temps exceed 95F (very low humidity).

Here's a comparison of stock carb, current race carb jetting, and one recommendation. First number is jet size in millimeters, and second number is jet size in inches.

Main Circuit Primary Main Fuel Jet
Stock 85 Manual 0.92 / .036
Race Carb 1.25 / .049
Recommended 1.02 / .040

Main Circuit Secondary Main Fuel Jet
Stock 85 Manual 1.60 / .063
Race Carb 1.35 / .053
Recommended 1.85 / .033

As is, the car runs extremely rich during partial throttle.

Also, it was recommended I remove the spring from the secondary venturi diaphragm. This should make the secondaries open super fast. Thoughts?
Thanks in advance for the help!

[Bench Racer]

Try Karl who owns a 1st gen RX7 in E production.

Karl McColl
RE/MAX Alliance McCOLL TEAM
EP #88
Homes4racers.com
Carbuffhomes.com

[G-Man]

Good suggestion, David. Karl's a darn good guy!
(Alas, he runs a Weber and doesn't know the Nikkis.)

[Bench Racer]

I would suggest Paul Yaw, but he can be a hard dude to get a hold of.

Try getting him through:

San Dimas Auto Repair
203 E Arrow Highway
San Dimas, CA 91773-3338 map
Los Angeles-Long Beach, CA Metro Area

Phone:(909) 394-1225