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Discussion Starter · #1 ·
Don't wont to start a war on here but im thinking of moving up to a 650 or 700 carburetor just wanted to know which carb u guys think is the best and most reliable for a 350 with somewhere around 340 or more hp. I didn't build the motor in my nova so i don't no everything that's been done to it but at the moment im running a 600 holly. So im asking with out causing any issues what's your opinion on Holly and edelbrock which have u guy's got the best performance and bang for your buck..thanks for putting up with guy's like me that's just starting to learn. We got to start somewhere and this seems to be the place to ask..
 

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IMO Edelbrocks are great for a street driven cruiser. If you are thinking about putting it on the track then I would go Holley.
 

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The Edelbrock is a glorified Carter and they are a good carb for a daily driver and can get decent mileage, had one on my dually and have one on my C-10 now and they work great, but for any kind of performance the Holley is the way to go..
 

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Discussion Starter · #4 ·
I was leaning more towards the holly carb but glad i asked. I just picked up a brand new holly street dominator intake from a friend of mine that needed some money so now i can go with holly on top of holly...lol....Thanks again u guy's are the best.
 

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Both carbs are good. The Edelbrock isn't a glorified Carter carb it is a Carter AVS licensed to Edelbrock by the Carter corporation. This is because Carter no longer made the older 1960s design AVS as they use their newer ThermoQuad (which Edelbrock can not legally as yet make) has replaced it in production cars made before everyone went to EFI. Edelbrock wanted the AVS because Chevy and Chrysler used those carbs on early sixties muscle cars that Edelbrock made manifolds for "back in the day".

Because Holley was the first carb company to make a 750 cfm and bigger carb all of the racers switched over to that brand as a single big carb is a whole lot easier to tune than two small ABS or AVS carbs sitting on top of a motor. Holley was the first to market with Double Pumpers (mechanical secondaries) and for an 850 cfm, a 950 cfm three barrel and finally a 1000 cfm small bore (4150 series) carburetor. This was just for bragging rights as the 750, 1050 and 1150 cfm Holley Dominators appeared on the market by the mid sixties to meet racers needs and the 1250 is now produced to meet the needs of all of those cars street driven on the internet that have a thousand horsepower (though I easily broke the 1000 horsepower barrier with my 582 BBC thanks to the addition of a 250 shot of nitrous all with ONLY an 1150 cfm Dominator on top of the motor).

So much for marketing hype. Let us discuss the real difference between the two carbs. First and foremost is that the Holley has the edge in ease of tuning. It literally used to fall apart with only the application of a straight blade screw driver. This is why every Chevy and Ford Muscle Car from the sixties had a hole in the drivers seat caused by a person hopping into the car to go for a ride after tuning up their Holley; and forgetting to remove said screw driver from their back pocket. I guess that was the reason Holley switched over to a hex cap on the screws that hold the fuel bowls on recently. It also helped to protect those expensive Corinthian leather seats in the SE Hemi 'Cudas and Chargers (and later Challengers) because they had twin Carter AVS four barrels on top of their "Rat Roaster" manifolds. Holley two barrels made up the "Six Pack" used on top of 340 and 440 motors so they were at risk however.

The real difference is in how the carbs operate. The AVS or Automatic Valve Secondary from Carter had a variable venturi secondary that they copied off of the Rochester QuadraJet. I really can not say Carter copied the design because physically they are different with the Carter being an improvement. But Carter did manufacturer the "Rochester" QuadraJet for GM when Rochester couldn't keep up with demand for the carb that was a run away success for GM and used on top of all of GM's four barrel equipped V8 engines. So they had really good insight into how GM engineers designed the carb.

A variable secondary has the advantage of not over carbureting a motor. If you get one that is too big for your engine bad things happen. Knowing that most street driven 350 motors would be quite happy with a 650. With a SBC 350 needing a 750 only if it was being raced at WOT, and even then using a solid cam to stretch the upper RPM power band. With a 750 cfm rated Carter AVS carb this wouldn't be a problem because the 750 AVS would never draw 750 cfm on top of the 350 unless the motor actually asked for it thanks to the variable secondary. This why everyone who has had experience with the AVS recommends it for the street. If you buy an 850 cfm and stick it on top of your 350, no harm no fowl you have in essence converted your four barrel over to a really big two barrel that might get more if you could spin it high enough. That is why GM put a Holley 850 DP on top of the Z/28 302 that spun to 10,000 RPM with stock 4.11 gears from the factory. It also explains why the 454 in an SS Chevelle had a 780 cfm Holley with a Vacuum secondary.

The Holley has a fixed cfm rating. It will flow less air at lower cfm ratings but performance will suffer on a 350 SBC because it is sized for a Big Block engine that will pull 750 cfm on the street, at lower RPM. You can not easily change the metering blocks to flow and mix the fuel to improve low to mid range operation and if you do it will adversely impact wide open throttle performance. In other words if you have too much carb on top of the motor it will load up and perform poorly at lower RPM operation until the motor can draw in enough air at higher RPM to obtain the design parameters of the carb.

People who have problems with Holleys are people who have bought too big a Holley and they then tried (or had a friend who was a "Holley expert" try) to FIX their problem by tuning it. I have been tuning Holley carbs for over a half century. I'm no expert, but I have learned from those who like Barry Grant (a lineman for Florida Power who was a well known Tampa Bay area racer who could tune a Holley) and Bo Laws out of Orlando are acknowledged experts. After a while I felt comfortable tuning not only my own carbs but others as well. I do know from reading plugs and oxygen sensors on my cars when a carb is too big for the style of driving being used. I just can not do that over the internet. You have to learn or rely upon some who knows what they are doing. If you think you have to tune a carb out of the box suspect you have the wrong carb first, unless you are actually racing or live on top of a mountain.

Big Dave
 

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Discussion Starter · #6 ·
Thanks Big Dave i have always told people when they asked why don't you u put a 750 on your nova my answer has always been i don't think my 300 hp plus motor can perform right with one. I wasn't 100 percent shure but now i have proof....Thanks a lot buddy.
 

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Most people wouldn't put a 1150 Dominator on top of their 275 horse 327 even if they could find a dual plane 4500 flange SBC manifold to bolt it to. Give them an 850 double pumper and most would be hesitant to try it, though if you actually gave it to them for free I am sure some would try it. So were do you draw the line? This comes from experience of knowing just how far to push the line.

Since I usually can find Holley 650 cfm 4160 vacuum secondary carbs at the parts corral at most major car meets for around $25 and the rebuild kit retails for $40 I can have an operational carb for under a $100. That carb came as standard equipment on small block Fords (later replaced with Autolites copy of the Holley) and International and other light trucks as well as a few Chevys running in the 300 to 350 horsepower range. It is dependable and unassuming. Doesn't have a chromed dual feed line or a polished appearance but it works as well as the newer ones do. It also provides a crisper throttle response on top of a 350 that a 750 dual feed 4150 model will even with dual accelerator pumps shoveling on the coals.

I say that because though I am not old enough to have actually seen a coal burning battle ship I know from being around coal burning steam engines that when they crack the throttle they bellow with lots of soot and cinders being pumped up the stack by the vented steam. (it was bad enough being aboard the CVA 66 America back in the sixties when she turned into the wind and went to flank speed to retrieve jets; there was definitely some smoke being made then). Get a carb that is too big for the motor and it perceives the low manifold vacuum as being a bigger engine accelerating or your smaller engine screaming high C. So it runs very rich.

Big Dave
 

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GM crate engine instructions recommend a 600 CFM on their 295 HP version of the 350. It's a Vortec but I suspect it's good advice for the HP you're getting. I love the Holley's but am going to the Sniper EFI upgrade on my 55 Chevy 210. Can't wait to get it installed.
 
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