48 IDA Interesting discovery

[priobe]

I am posting this to gather knowledge on the behavior of your 48 IDA and how it works in your application.

First, I would like to ask how well your motor is running. By this, I am simply asking are your plugs a tanish brown, and is your mixture 14.7 - 13.5 while driving and at idle.


I had very interesting conversation the past couple of days with a gentleman that had extensive knowledge with the 48 IDA (finally). Our conversation went in to great detail. As we were talking he pulled out a 48 IDA (cut in half) and explained from start to finish how the carb operates. He also explained the "Myth" as to why there is a certain type of camshaft spec for motors using the 48 IDA.

After explaining, he proved the "Myth" to be wrong. In his shop he fired up a motor that was in a RX 7 and show me the tach that was bouncing from 1600 - 2200 RPM (rotory) . Of course this was all out race car. After allowing the motor to warm up we took the car for a ride. I cant say that the idle was good but the mixture was good. Off of idle through the progression circuit and on to the main circuit the car drove flawless.

After heading back to the shop, we took another rx 7 for ride this one was more tamed but the drive from off idle to main was the same.


He explain to me that most people shoot in the dark when they tune these carb. By this I mean over riching circuit to solve the problem. He also mentioned its not that difficult.There are alot of variables involved.

Camshaft
rear gear
weight of car
altitude
transmission gearing
fuel pressure

With this being said, it is almost impossible to give someone a jet value and have them run it in their car and expect it to work. On the same token to troubleshoot a problem by hearing a person say I am having problems at a particular RPM.

You might be asking well why dont I just have him tune my car and solve the Weber problems for good.

Well, because I want to learn. Also if his practice is true I want to know how to so solve my problems in the future.

Note: By the way chokes are not needed in the 48 IDA if your looking for more volume of air at higher RPM.

I rather not yet post the information that was discussed until I try it out on my application. Things such as fuel pressure, float level consistancy, how to tune drivablility progression circuits.


However, I would like to hear how your motor is running with 48 IDAs.