Hot Rods Do I need special carbs to run on a 671 Blower

As title says also street only
Thank you

 

Not necessarily, but they have to be "boost referenced". Lots of articles about that on the web. What kind of
carbs are you running. I last used two 650 Holleys on a 350 sbc on the street. They worked great.

 

They don't have to be boost referenced, but they can be. I've never bothered...seems they do fine without, if you don't go crazy on the boost, compression, etc.

I ran a pair of 4777 Holleys on the 454 in my 55 for a long time, and now have a pair of 9755 Carters on the 427 in my Chevy II. Neither one ever went over 8 psi boost. The stock jetting in most "hot rod" carbs like these is on the rich side, and will work ok with a blower.

 

Jim, did you ditch the power valves or were they already plugged. On the holleys I mean. Lippy

 

I left the power valves in.

 

Thanks.

 

I have a pair of 650 Holley with vacuum secondary's

 

Pair of old Carter Competition 750s with 389 cubes at 10# of boost. I started out with two 600s, but it was WAY lean on the dyno. They are not boost referenced but are rock solid and trouble free.



-Abone.

 

It seems you need bigger carbs to seal the blower up with fuel WO. Since on a street blower not many run stripped blowers. Teflon stripped I mean. Lippy

 

A loose blower is your enemy. Lippy

 

Boost referencing can be done with Holley or Edelbrock/Carters. It is not necessary, but it can bring better throttle response depending on the build, cam selection, and a variety of other factors.

It will allow you to run smaller carburetors, without fear of lean-out, as they will more closely follow the demand curve from the engine. This can improve performance/driveability on the street, where you (I hope) are not pedal to the floor, all of the time.

As I am fond of mentioning, rich and lean are not a factor of CFM. Rich and lean are factors of jets, step-up springs, metering rods, etc. CFM is maximum efficiency point. Yes, above that you will start to go lean, if you get there. If you are enriching your fuel mixture by using a larger carburetor, or carburetors, you are incidentally getting richer, because those carburetors have larger jets, step-up springs, metering rods, etc. You can just buy those. They are usually pretty cheap.

For less than the price of a single new carburetor, you can get a wideband Oxygen sensor, and prove it for yourself. You don't even need to leave it in the vehicle, just tune, and then take it out.

In any case, we'd all need more info about what you are building, what size engine, which cam, compression ratio, what heads, etc? Give us as much info on the engine as you can.