Thread: Holley HP carbs--aluminum and lots of other improvements

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Maybe they're not new, but it's the first time I took some time to look at the HP carbs made out of mostly aluminum, lots of good changes and probably a whole lot more adjustable for racing and street!

Anybody parted with the $$$$$ to try one out yet?

Here's a link to the Holley site showing the carb and it's improvements;

Holley Performance Products 600CFM Shiny with Black Billet, Aluminum Ultra HP*0-80801BK

i just bought one!!!! its the centre piece on my dining room table at the moment lol. it will be a while before i actually get to use it but i'm super excited. i bought the 950. i was told to go big and then jet it down to what i need so ya thats what i did!!!!

Well, if they look as good "live" as they do in the pictures, it would make an excellent centerpiece!!!! 950 is huge! Hope it's going on a big incher with a big set of heads???? They've even got secondary linkage adjustment like the Dominators, I like that!!!!

okie this is my first build so if it sounds like i don't know what i'm talking about i some what don't so i'll do my best. its a 396 bored .30 over stroked to 434. keith black 10:1 pistions and 110cc edlebrock aluminum oval port heads. thats where i'm at so far.

Wow!!! That's a lot of carb for that combination. IMO an 800 would probably work better and offer a lot better driveability on the street.... 950 would be more for like a 496-540 incher with the huge 345 runners and a narly roller cam.. I only ran a 850CFM on a roller cammed, Kaase design SCJ headed 501 incher on the street and it was just about perfect on air/fuel ratio from 1500 to 6500 rpm....

Down jetting a too big carb can cause other issues in the part throttle and mid range rpm....though it will probably work fine at WOT, the engine might be fat and lazy at anything less.....

well its a learning process for me i kinda have to take everones opinion and choose for myself. the guy who's overseeing the build suggested it because he has a very similar set up and he used a 1000 cfm carb and jet it down i guess i'll just have to see. maybe i'll be buying a different carb!!

I've been using those aluminum bodied carbs for quite a while, they're developed by quick fuel and proform and when they get debugged holley starts selling them. They are great carbs, esp the proform street carb which is basically a race carb with a nice electric choke. I've been using them for about 3-4 years and the only issue is that they are more sensitive to heat so you need to isolate them with a wooden or resin spacer (i'm not a big fan of the plastic they are now using and calling 'phenolic').
And, i agree with Dave, the 950 is too big. Jetting a big carb down is problem solving not tuning. The 502/502hp gm crate motor comes with an 870 carb - roughly 10% smaller than your carb on a 15% larger engine. A 750cfm would be just about right.

I have used a lot of carbs that big on engines that size and occasionally even smaller----it takes a few different approaches to idle air, transfer slot mods, accel pump and nozzle choices, selection of power valves and also a very fine tuned distributer advance mechanism. They can start good, idle fine and give decent milage as you will mostly be on the primaries without tipping into the up tuned seconary side except when you have some open road ahead of you!!!

I have a 71 455 in my 69 GTO with KB pistons and all I had was a 600 edel at the time which I thought made it run good. This year I picked up a 750 edel. So after putting that on it made it feel and react like it had 2 more cylinders. I could have probably gone bigger. Sounds like it may be a fast car there Chevygirl. But that is alot of carb to be dealing with. Good luck and have fun with it.

Well don't be surprised if that 950 cfm don't work fine as is. A 950 is really about a 850 with a 750 main body. It does't flow no where near 950 cfm. I had a 454 ci bored .030, KB domed pistons, ported factory oval port heads, about 11:1 compression, crower mechanical roller cam: 641/636 lift and 252/262 duration, Edelbrock Victor jr with a Holley pro series 850 cfm. I rejetted it up 1 size front and back but had to go back to factory size on the front. This was in a 67 Camaro with an 400 auto, W/3600 stall and 4.11 rear. I have recently rebuilt that motor to a stroker 491 ci. I modified the carb with a perform billet base plate and main body. I haven't installed it yet, still getting the body ready to paint. The 950 is supposed to give a better signal for throttle responce than a 850 does. It all depends on the rest of your setup. I think it is a good choice. Good Luck!

A rule of thumb which seems to work well as a start point is cid X 2 equals cfm

Check out this link from Holley, want a good baseline to start with. Could be called a carb desktop dyno


Holley Interactive Carburetor Selector


let me know how you like it ..