Carbs

[Jim Vorhees]

Anybody have three two barrels on a Chevy 350? I like the look but at $1650.00 I need to know more about performance. I only get 10 miles per gallon on my souped up 350 ( roller rockers,cut back valves,525 cam,hyd lifters,and a 750 carb which may very well be the problem). Thanks in advance.

[Harry Craycroft]

Hey Jim, I'll give you my two cents on this. Everyone that I know that goes for the three two's ends up taking them off down the road due to high gas consuption and always tunning. If you are running a 750 at present, I would go down to a 650 or 600 for better gas milleage and roadworthy operation. That's my two cents worth.

[Steve Stock]

I wonder what linkage they were running with the three dueces. Seems that a progressive linkage where the center carb is the only player at idle and cruise should do well. At least that is what they say. I haven't had the three carbs before so I'm shooting from the hip here, but would like to know too.

[Bob Lemke]

3 dueces set up with a sliding progressive linkage produces good off idle performance and if you don't bury your foot in it, good mpg. The advantage of this set up is for the first half of linkage travel only the center carb is being opened. When flowing through a small single carb, the flow is at a higher velocity and for off idle response a single small two barrel gives much crisper acceleration than a larger carb. 90+% of your driving is from off idle, not foot mashed, so if you got the coin and like the look, you will like how 3X2 performs with the correct linkage set up.

Just my 0.02 worth, and not even worth that.

[Jim Vorhees]

I am hearing from all of you the same thing I hear with the guys in my club. Linkage seems to be the major key to making this system perform. Harry, I also like your idea of a reduced size carb, that was my original though. I to have heard of a few guys taking the three set up off. Thanks to all of you for your quick response.

[Bob Lemke]

Jim,

In my younger days I bought into "big is better" even for carbs, silly me. I had a blown 427 Ford side oiler that I had dual 600 CFM and as in the case of being over-carbed, had a bog. As I started learning more I came to realize what I had done wrong, but being young and not flush with coin, I had to find a way to dial this in without running out and buying (2) 390 CFM four barrels which at a total of 780 CFM, would have only been slightly over-carbed. Of course the first thing I did was just drop the linkage off the 2nd 600 CFM and it was a night and day improvement. I was afraid to leave it that way because I feared at full throttle the 4 cylinders furthest from the single carb could go lean on me. So I fabricate a sliding linkage and mount it 2/3's closer to the throttle shaft than the stock location and this reduced the moment-arm so that when the sliding linkage came to the stop that begins actuation of the 2nd carb (about 3/4 throttle pedal movement), it takes a short distance pull to get that carb from first cracked to wide open. Worked great. These were the only pictures I could find, don't have a good one of the linkage.

On the picture below, how do you like the plate held in place to the air box with valve springs? In event of a nasty backfire the hope was the pressure spike would vent past the plate as the springs would compress instead of launching the blower to the stars.

[Harry Craycroft]

Jim, Let us know what moves you make on this carb thing and how your changes, if any, worked out for you! We would like to see you happy with any changes that you make!

[Jim Vorhees]

Not really set to jump just yet,but it sure looks like it all revolves around linkage. My bucket runs super right now so that alone has me wondering if it is worth it. Thanks for you concern.

[Harry Craycroft]

Go for it Jim!