Need advice on carb selection....

[HotRod47]

I recently acquired a 66 Chevelle that has a 454 in it. It has a very stout cam, has Rectangular port 69 Corvette heads, and open plenum Weiand intake and a AED 850 carb on it now. This is a 4 speed car if that matters much. I just did a rear gear swap to make the car more drivable to my liking. The guy liked stop light to stop light cruising and had 4:88's in it!

So with 3:55's the car is definitely more drivable. With the cam that is in it I need to pull away from a light or stop sign with the RPM's up higher then I like. I have been told by many to swap out the intake and carb to a duel plane intake like and Edelbrock RPM or something like that. So that is next, but what about the carb? What do I really need?

Planning to most likely get a Holley, but which one? Is a 750 the only way to go hear? Is the Street Avenger 670 too small?

Remember, this is a street car. I will never take it to any type of track, drag or autocross. Cruise nights, local car shows, out with friends etc.



Appreciate any advice you guys can offer.

Thanks,
Glenn

[65 drop top]

Swapping the intake and carb may help increase bottom end torque, but with a big block you will already have plenty. It sounds to me like maybe you have too much cam for the street. Do you know the cam specs?

[Sean Cooke]

http://www.gtsparkplugs.com/CarbCFMCalc.html
Not the end all solution for picking a Carb but maybe a guide to get you in the ballpark..

[TheJDMan]

Personally, I would not spend any money on a carb. Take a look at FITech they offer a reasonably priced throttle body EFI which will outperform a carb.

http://fitechefi.com/

[another69]

I had a great experience with Pro Systems when I bought my carb from them in 2007ish. Best carb I ever had, no doubt. You give them all of your vehicle info and they "build" a carb to match. That being said, this year I swapped to efi and will never go back.

[HotRod47]

I am going to install EFI on my project car, but on this one I just want to replace the carb and call it a day. I plan on selling this next year and really don't want to invest the money to put injection on it.

[another69]

Nothing wrong with going with a carb, but are you sure that you have a carb issue? Do you know your cam specs and your compression ratio? If those are mismatched you may never make good low end torque. Same goes for a motor with a big cam built for high RPM- generally low RPM power suffers. You may just need a new intake and flat tappet cam, which would be cheaper than a high end carb. More info on the motor would help...

[matt816]

Tune the current setup. Plugs, timing and idle circuits. Measure your vacuum at idle, 850-900 rpms. below 10" and your cam most likely doesn't like the new gears. Im betting its not tuned for normal cruising and the cam is too big

[HotRod47]

Nothing wrong with going with a carb, but are you sure that you have a carb issue? Do you know your cam specs and your compression ratio? If those are mismatched you may never make good low end torque. Same goes for a motor with a big cam built for high RPM- generally low RPM power suffers. You may just need a new intake and flat tappet cam, which would be cheaper than a high end carb. More info on the motor would help...



I know it isn't a carb issue per se. But I am still trying to get an idea on what people suggest.

Big block with a huge high RPM cam, an open plenum Weiand intake and an 850 AED carb. Carb has been set up to flow at a little over 900 cfm. The engine dyno'd at 589hp as is. HP is fine, but the set up and parts selection is way too much for the street. I was hoping to get away with a intake and carb swap, but the more I drive it, the clearer it has become that I must do a cam as well. I have consulted with Competition Cams as they did the custom grind on the cam that is in the engine. I want to find something compatible with the rest of the engine, heads etc. I have done that now. New cam on order, as well as a Edelbrock RPM intake. Still unsure what I should get for the carb though.

Glenn

[another69]

Sounds like a pretty stout big block! What makes you think that you can't use the AED that you have now? Is it a mech. secondaries? For that motor it would probably be best. If you are asking for suggestions, I would say the best carb will be one custom built by someone like Pro Systems. The next best thing would be to tune what you have now VIA a wideband O2 gauge.

[alky]

See you have sold the car, never mind
good day.........

[sam 74]

take a look at FITech, its worth it, but if you're set on a carb i wouldn't go smaller than a 750 with any kind of work done to a big block, you may want to consider an HP series type of carb, or if you have the specs of your motor you can always have a carb custom built to your motor which is usually what i do with high performance stuff, they just run better than an out of the box carb.