Edelbrock's are somewhat self-regulating if an oversized carb is used.
The engine doesn't pull the air controlled secondary valves open all the way if the carb's CFM rating is not reached.
By the same token an undersized carb will pass more air than it's CFM rating if the engine can pull the CFM.

Since the 600 carb is already installed, make the best of it, jet, rod & spring it to suit the purpose and run it for a while.
Since the carb will seldom be under full throttle I'm sure you'll find the car to have good manners in the driveability dept when on the primaries.
Speaking for myself, if I was running a 283 I wouldn't worry about replacing the 600 Edelbrock.

Years ago, a friend stuck an 850 Holley on a 283 powered El Camino.
I thought he was crazy, but it ran prety good.
He did go to a smaller Carter later on and the 850 Holley was a temporary expedient.
Interesting to see though.

Along those same lines, I oughta con my pal into sticking one of my jetted-for-the-altitude 750 Edelbrock carbs onto his 327 powered 29 roadster.
He's running an overly rich 600 Edelbrock right now and it runs quite well.
Pretty much a stock 327 with a bit of a cam, headers (inefficient block huggers) and a whiny gear drive.
I'm betting the 750 would run pretty good.


Fwiw - couple of years back, Car Craft ran some dyno tests on what were considered oversize carbs and had very good results.
Not sure if it was in the same article or not, but they also found not a whole lot was to be gained by port matching - as long as things were fairly close, good enough.

That article and personal experience makes the old carb size formula an ok place to start, but it ain't the end-all and be-all far as carbs go.


Quite a few years back, Holley ran a vendor/tech help tent at the WinterNats.
They found most problems were cured by returning the carb to factory baseline.

My opinion is that most carb problems with new carbs are simply an incorrect choice by the purchaser.


One last story and then I'll shut up.
About three years ago I went into my favorite speed shop.
A small one in Farmersville, California that carried a lot of genuine speed equipment and stuff for the hard-core drag race crowd.
No bling wheels here although there was a stack of gennie Halibrands on a big shelf high up on the wall.
Along with $30,000. worth of Earls fittings on the other wall.

The owner always had a few intakes, some with carbs, a couple boxes full of used stuff at good prices etc.

One bright and sunny day, I spotted a brand new looking 750 Edelbrock sitting on top of the stuff in one of the boxes.
It was about two weeks old and the speed shop owner thought the kid who bought it had mis-jetted/rodded it.
The kid brought it back cuz he wasn't happy with it and had gone to a Holley.
Which is ok, but since he couldn't make the Edel run, my bet was it wouldn't be long until he painted himself into a corner with the uber-adjustable Holley.
Said adjustments not being a bad thing, in fact a very good thing for some.

Anyway, I asked how much for the carb that the owner had bought from the kid and the price was $125.
Not bad considering the thing cost bout $287. at the time

I bought it, jetted it to the factory baseline level and it ran great.
It's the same carb mentioned above that was later jetted for 3400' altitude and it still runs great.

I don't know what happened to the kid, but I sure am enjoying his 'old' carb....