Carb dilemna

[So Cal Mark]

the distribution on the stock intake is horrible at best with 2 and 3 already getting more fuel than 1 and 4. One nice feature on the DGES carb is that you can stagger the jetting between the two sides to even out all 4 cyls

[baltobernie]

Bernie, I have a fitting that came with an old Bayless 1 3/4" high lunch box style air cleaner.

Thanks, Matt. I will see how things go with external filter for now.

Mark, I think that the carb spacer will help with dilution, plus the DCD is way taller than the DGS. The butterflies must be at least an inch further upstream than the DGS. I never noticed a difference in plug color in "inside" vs. "outside" cylinders using the DGS, with identical idle jetting in both barrels.

I'm still experiencing difficulties in "high load, small throttle" conditions. Ignition timing nor idle jetting fixes and adjustment fixes this. I'm gonna wait for Matt's Weber book to arrive; maybe Passini's book will provide some insight.

[baltobernie]

Good tip on the Passini book, Matt. But it is not for the impatient reader! Some fine examples of British humour, too.

I'm pretty close now with a 155 primary main jet, so it's off to the mechanic for valve adjustment and cam timing check. Passini (and others) repeatedly stress that all mechanical and ignition components must be in spec before attempting to fine-tune a Weber carburettor. For example, I've got a massively entertaining overrun symphony. Is the idle jet too big? Or is a valve or two or eight not closing at the right time? Right now I'm guessing; next week I'll know for sure.

[manoa matt]

Yep, he is a bit hard to follow at times. I suggest keeping a pencil or pen handy, and when you read a sentence that applies to your situation or is a good rule of thumb, underline it. You will never remember it or find it later.

Overrun, no fast idle system is one, exhaust leaks is two, play with the jets is three.

[jetboy]

I wonder if this orientation will cause cylinders 2 and 3 to be rich, while cylinders 1 and 4 go lean when running on the primary throttle bore. When the secondary opens it should even things out. The reasoning being the primary throttle would dump the mixture right in front of the No. 2 and 3 cylinder runners and get sucked in before branching off to cylinders 1 and 4. Where as with the typical arrangement with the primary throttle being further away on the manifold, the mixture can drop and spread out more before being sucked into the various intake runners. A simple plug inspection would reveal this.

Bernie, I have a fitting that came with an old Bayless 1 3/4" high lunch box style air cleaner. It mounts on the side of the element and you can attach the breather hose, it's yours if you want it.

this should not be a problem as the cylinders only suck in the downstroke/valve opening and do not directly compete with each other. that is why having one carb works at all. if the cylinders were all trying to suck the same source at the same time that little carb could not keep up in any case!