Hello, I have a 3x2 setup with Rochester carbs . I am having trouble figuring out the connection from the center carb to the rod connecting the outer two. Any pictures or advice would be much appreciated. Thanks I just attached a photo of my linkage. It looks close, but when I open the center carb all the way the outer two only open slightly, no matter how much I adjust the linkage. What am I overlooking?
Progressive. I have tried it different ways, but when I open the center carb all the way, the outer two are barely open.
Along with a sub-forum for brakes only, we need one for 3 deuces. Put the knowledge in one place. front and rear carbs are connected. center carb moves a rod to a stop which opens front and rear
The easy (and often the least expensive if your time is worth anything) way is to use a set of factory carburetors with factory linkage. The center carb is connected to the rear carb using an adjustable slotted rod. The adjustment of the slot controls the RPM when the rear carb opens. The front and rear carbs are somewhat LOOSELY connected (a solid connection will just about guarantee some issues because of the different coefficients of linear expansion of different metals). The rear carb has an arm on the side of the carb opposite the pump with a round hole. The front carb has an arm with a horizontal slot on the side of the carb opposite the pump. The front and rear carbs are connected with a rod with an "adjustment bend" (not a perfectly straight rod). The rod is adjusted by bending such that the end of the rod is centered in the slot of the arm on the front carb. This allows both carbs to be completely closed whether the engine is not or cold. Due to the position in the slot, the outboards will open maybe 1 or 2 degrees of rotation differently. This is not an issue. Ford factory linkage (Holleys) is different from the factory Rochester linkage, but uses the same principals with slots. If making one's own linkage, or attempting to use some A/M linkage, the principals above should be observed, plus one needs to consider position of the links on the throttle arm such that the outboard carbs will rotate faster than the center. This allows the outboards to not open until a predetermined throttle position of the center, but rotate to the WOT position at the same time. If one compares the relative distance of the position of the linkage to the throttle shaft on the factory carbs, one will find that the linkage is positioned closed to the throttle shaft on the outboard carbs, allowing them to rotate faster than the center. The paragraph above probably explains the issue currently encountered by the O/P Jon
What you have there may work. Move that collar on the left side of the new kit much closer to that center slide that connects to the center carb.
Your problem is in the length of the arcs your linkages are traveling. It looks like the linkage on the center carb is closer to the throttle shaft than the linkage on the front carb. Even if they are the same distance from the throttle shaft it won't open the end carbs very far because the linkage from the center carb has to take up the slack to the stop on the shaft before it can move the secondary carbs. That is what those two perforated flat links are for. You use them to move the pivot on the center carb farther away from the throttle shaft and move the pivot point of the front carb closer to its throttle shaft. What you are trying to do is have enough travel left in the arc of the center carb to open the secondary carbs all the way. When I set mine up I looked at a 4 Barrel and used that as a guide to see when to start opening the secondary carbs. Somewhere around 60-70% of primary travel, if I remember right. Edit- What Carbking said. Home made linkage from 30 years ago. Black bar bolted to the center carb linkage to extend its travel. Slotted rod to the front carb instead of a stop. End carbs still closed, ready to be opened. All carbs fully opened.
This is how I did mine back in the early '80s. The long lever on the center carb ( in relation to the end carbs) is what allows the end carbs to be closed until the center is 40-60% open and all 3 to be wide open at full throttle. IIRC I had a slot in the center carb lever to allow for adjustment. I made an extended throttle shaft for the center carb also.
There are many different thoughts on setting up the linkage. What typically works the smoothest and allows adjustment is moving it to the passenger side. This requires extended shafts on all carbs. Also setup the front and rear carbs as secondaries and configured as such. Not an ad, but I build custom vintage induction systems. Please message me and I'll help you with questions. Here are some pics of what I build and shows how it's configured for smooth operation. Brian
The Jalopy Journal
