2 Barrel or 4 on a Centermount

[PHX65CorsaHT]

Let us know your thoughts/experiences with with using either a 2 or 4 barrel carb on a center mount setup. Kick us anything regarding appropriate jetting size etc depending on running the 2 vs. 4. I have read about the CFM size that should be run but havent really seen anything regarding running 2 barrels all the time vs the primary/secondary 4 barrel. Thanks again everyone.

[Smitty]

I recently bought a 66 with the 4 barrel intake mod. It had the rochester 4 jet carb but it was not any good. So I bought an adapter for a 2 barrel. I put a 2 barrel carb for a 289 mustang on it and it runs really good. Good throttle response with NO lag. It does not load up and get rich. Funny thing happens when the humidity is high. The intake sweats and is covered with water droplets. Also very cold. Just my 2 cents worth. Good luck.

[PHX65CorsaHT]

Smitty.. thanks for the reply. I just changed engines and the centermount is a two barrel. I should have it running in a few days. I will keep in mind you are using a 289 two barrel if I need to change it at some point. Do you happen to have any pics of how your throttle linkage is setup? Thanks again, Joel

[Smitty]

I'll try to get a couple pics for you.

[Smitty]

Here are a several pictures. I do not know details about the cable or the bracket mount that you see attached to the fwd two attach points on the carb. The clamp is temporary till I figure ou where to drill or modify. I hope these help.

[Smitty]

I forgot to tell you that the 4 to 2 adapter has a front and back with this carb. The carb has a bump on the bottom and the adapter will only go one way.

[PHX65CorsaHT]

Thank you for posting these pics. Time to get that linkage together!

[Phil Dally]

I have a 2 barrel Holly on my racecar.

I use a Morse cable from the tunnel bell crank.

These pictures are cell phone quality but you'll get the idea.

I recommend a Holly because you always know what you're going to get.

Plus parts are vairy available at all regular normal auto parts stores.

Either a 500 like mine or a 390 4 barrel like the one pictured.

Jegs, Summit, and Speedway all sell them both and Morse cables ready to bolt on.

The last two shots are my original Morse cable bracket that is for sale.

It bolts under the carburetor and to the back side of the cove area.

No vibration problems because the center mount is connected by the 4-leg rubber.

The Morse cable is flexible and can be mounted from any direction.

P/M me if your interested in that bracket for $25 OBO...I'll ask Mr Kat if I can sell it.

[PHX65CorsaHT]

Thanks Phil. Turns out my Holley is a 500 cfm. Just had it rebuilt. The engine is moderately built so I hope the cfm will be a good match for the engine. Should be ready for first shake out drive next week. Thanks again.

[zappaz]

the water drops is mainly dew to fule mix temp the long tube alows the temp to drop in such a fashion i been thinkin about this latley and with wat i learned and wat i no is a heat sourse would greatly improve performance ''like the vw bug '' my thought was this : weld a box under the remote carb set up with 2 fittings use a remote oil filter set up and plum yr oil to the box and back out this would warm yr intake and help the fule vapor from forming into droplets this is a given a v8 sits ontop of the motor the 4 & 6 cyl sits on the exsaust and i belive this would aid to oil cooling i have a 2 into 1 2bl intake sitting here ''in the living room y not its chrome and ol girl aint happy '' but im waiting on a few things be for i try this
leaning towards a 140 motor swap so i mite not even use it

[UNSAFE]

My two cents -----

500 cfm is way too big for anything less than a race motor.

The bigger the carb the slower the intake air is moving. You need the velocity to make the carb work as designed . A fast moving intake will help atomize the fuel and will prevent precipitation.

A 500 cfm 4 barrel will have much smaller diameter butterflies than a 500 cfm 2 barrel and the drive-ability at everything less than WOT will be better with the four barrel.

Not too mention the considerable distance that the intake charge has to travel while displacing the mixture that is already in the plenums and intake runners . There is no way that it can have as good of snap response as a stock set-up with the carbs close to the intake valve.

[PHX65CorsaHT]

Agreed on all counts. The only thing I have going for me is I live phoenix. The weather may help some on the fuel suspension issue. On the other hand I guess I will have to have my reserve heads ported and angle tubed to handle carburation! I would like to go back to the orig 4 carb setup. Need to rebuild them first. But the 140 I pulled from parts car already had this setup so I will try it. It would be cool to have first hand knowledge of the performance/drivability difference of the different carbon setups. Plan to drive for first time this week! Thanks for replies!

[Smitty]

Kevin, I didn't know what to expect when I put the two barrel carb on my 110 hp. I thought , like you, that there would be a lag in the throttle response. Not so. It is like RIGHT NOW !!! I wish I knew how to put a video on here to show everybody. I am very happy with the two barrel. Just my 2 cents worth.

[Scott V]

My two cents -----

500 cfm is way too big for anything less than a race motor.

The bigger the carb the slower the intake air is moving. You need the velocity to make the carb work as designed . A fast moving intake will help atomize the fuel and will prevent precipitation.

A 500 cfm 4 barrel will have much smaller diameter butterflies than a 500 cfm 2 barrel and the drive-ability at everything less than WOT will be better with the four barrel.

holley 2bbl carbs are rated @ a different pressure than their 4bbl carbs. a 500 cfm 2bbl carb would probably flow about the same as a 370 cfm 4bbl.

-Scott V.