I'm going to go ahead and disagree with the notion that the problem is the brand of the carburetor. I have two Edelbrocks on mine and it runs like a top. I spent a fair bit of time tuning them, but they work great.
As was said in an earlier comment - the Edelbrock is an AFB clone. I had great luck with Edelbrocks on my Mopars, so when the 425 was built, even though it came with a Quadrajet, I switched to the Edelbrock. I had some issues with the first carb that I bought, but the grubby old Edelbrock that I removed from a total POS Chevy pickup that I was going to scrap, has worked beautifully. Using 20/20 hindsight, I am thinking that the problem with the first carburetor may have been fuel system rather then carburetor related. I'm going to use that carb on my dual Quad setup.
I am just reading this thread to be informed. Thank you to all who have posted helpful comments. I am no longer necessarily in the hobby but will be purchasing a project soon to do with a young man who recently lost his father and needs this sort of activity. So - even though it has been stated you can not over carb an engine, would there not be a reason for a stock size cfm carb for a particular motor from the manufacturer? For instance, the OP has a 364. Wouldn't GM/Buick have placed a 625 4 barrel on there in most cases (I am guessing at the cfm, but I would guess it originally came with a 500-625 cfm 4 barrel. And number 2 - what cause a used carburetor to not be rebuildable? Are you saying that at some point the carb core becomes unusable? I have rebuilt a few carbs many years ago, and I would go to the auto parts store, buy a rebuild "kit", clean the carb, reinstall components and away I would go. At some point in the last 20 years did carburetor cores become unusable, maybe from ethanol in gas? Just curious what I am missing.
i think 2 things that the average rebuilt would be hard is the base plate is warped not likely but more likely the throttle bushing is worn.
The CFM of a carb is its maximum flow. If the carb is calibrated and jetted properly, it will only pull what it needs. Edelbrock carbs are one size fits all, at best jetted rich, and at worst sloppily built and assembled. Rebuilders like Tomco use assembly line workers who dismantle, chemically clean and reassemble carbs from multiple parts, repairing or replacing the damaged things they do catch with bottom dollar parts (the jets are sorta close to the size they’re supposed to be). Warped lids get reused, bent hardware is ignored, worn bushings ignored, and none are test run. Speaking from experience as both a buyer and seller, people who knew what they had wouldn’t turn in a ‘good’ core either; they’d put the worst one they could find in the core box. Patrick
i don't get how one size fits all. so in that case why wouldn't Edelbrock just make 800 cfm carbs it would be a lot cheaper and less inventory then having 500-600 650-750 and 800 cfm carbs?
I believe you CAN under carb an engine as far as airflow is concerned, then performance suffers because you can jet it up without it going rich from lack of air.
When I say ‘one size fits all’ I mean that they sell one 750 cfm carb that fits a Chevy 289, 305, 350 and 400 along with all Buick, Olds, Pontiac and Cadillac V8s, plus any number of non-GM products. In 1970, Buick 455s had at least four different Qjets-auto vs. manual, standard vs. Stage 1. Something about each application was different, and new a ‘70 Stage 1 GSX, with a stock cam and driveability suited for a new near luxury car, would run 13.38 in the quarter yet raise no complaints from Buick’s picky customers. Patrick
All a carburetor knows is air flow and pressure drop. That's it. This is why they make calibration kits And why GM made different "models". They were calibrated to each engine's needs. You do need to match carburetor size to air flow requirements for best performance. That is why there are different throttle plate and venturi sizes. A 750 will never perform as well on the street as a 500 on a 289. It might make more HP on the dyno and the drag strip but most of us are concerned about drive ability.
There were several comments made about running the carburetor right out of the box vs tuning the carburetor. It is my opinion that initially you should run the carb out of the box for a bit and find out what you have. My new Edelbrock needed a bit of tuning, but Edelbrock sells tuning kits that come with instructions. The old POS grubby that I grabbed off of a SBC that I was going to sell Ran fine without my doing anything but cleaning it, but when Tom Telesco redid my engine he also did the carb. At that time he told me that I should move up to a 750cfm and it's still on the "to do" list. My skill set is that I can do a disassembly and basic rebuild of most carburetors - I love Holleys, but detest working on them. It is for this reason that I run Carter or Edelbrock Carburetors. I also have nothing against Quadrajets, and I find them easy to work on, but IMHO they are ugly.
