428CJ carburetion

[saltshaker]

What are you trying to do or get out of the motor with a carb or linkage change? What's your cobra not doing for you?

[wemooz]

It is the question of the unknown. Here I am with my ERA cobra that I have been happy with for 21 years. But, since I have a pair of 390's and the original cars had a pair of bigger carburetors, I wonder what the difference would be if I changed from 390's to 600's. It is an academic question, and if someone tells me that using 600's would be far more satisfactory as a daily driver, I might be inclined to make the change. The subject of progressive linkage entered this question from left field, but it is there and it is a valid consideration. So I am not saying that I am unhappy with the 390's, but I am curious about what it would be like with 600's (probably with progressive linkage). Thanks for your questions, but this is an interesting learning experience for me.

[ERA Chas]

Originally Posted by saltshaker

What are you trying to do or get out of the motor with a carb or linkage change? What's your cobra not doing for you?

Exactly the point.
Unless you have an aggressive (not race) cam and heads that flow 280-300+ CFM just stay as you are.
A. It works and is not problematic.
B. You have no demand from the other systems in the motor for more carburetion.
C. It's the least expensive thing to do.
Take the advice from Holley man with a boulder of salt.
Progressive linkage alone will not lean certain cylinders. That's more a function of which intake you use.
Larger than 390's are NOT too much for your combination. Vacuum simply allows the engine to only use the CFM it wants, making larger carbs a bling thing.
You're fixated on progressive-or-not linkage.
A. Leave it as is.
B. Experiment and vary the rear carb feed-in in small stages.
C. Experiment and make a 1:1 link and see how it runs. I did, it does.