a weber problem. one carb only, 40idf Options

[rhodyguy]

i'm stumped. at idle, i get a pulsing of fuel out of both of the accelerator pump jets on the pass side carb. they do not not leak with the engine off, with the key in the first position and the fuel pump engaged. driver's side does not exibit this. it occurs whether the linkage is hooked up or not, and the engine is idling. valves adjusted. i've been thru the setup proceedure repeatedly. side to side carb flow is balanced.

give me some ideas. the actuating arm is not bound on the cam and moves freely. so...incorrect float adj? stuck diaphram or one of the check balls missing or stuck? looking at the cutaway diagram on p58 of the cb book shows a good view of the circuit. there can only be so many issues.

i contacted the outfit that rebuild my carbs. their diagnosis was tight intake valves and the back pressure upon compression was forcing the fuel out. that didn't make any sense to me.

k

[rhodyguy]

i'll use this thread as a continuation of the discussion. i have options. i have a set of 44s (italian) available for use. in the first set of pictures i'll share the difs. the 44 is shown on the left.

1. note the dif in the adj pump jet rod vs the solid non-adj style on the 40.

2. note the 'helper' spring on the end of the throttle shaft and the lack of on the 40.

3. the idle adj screw contact arm is 'clocked' differently on the 44. on the 40, the linkage connection points in the correct orientation. it makes for the proper operational direction and maintains fairly verticle linkage drop rods. hopefully i can swap out the one on the 40 to the 44. my linkage 'swings' down as opposed to 'pulling' up to open the throttle plates. i've wondered why folks run the linkage on the rear side of the carbs. i think this is the reason.

4. the main jet stacks are quite tall on the 44 as opposed to the 40.

the 40s have 28mm venturis and the 44s have 36mm. reading harney's recommendation of going 4-6mm smaller than your intake valve size, puts me right in the ballpark with the 42mm valves on the stock 2.0 heads. i 'think' arron has gone to smaller vents on his hopped up 2.0, 32s?

i feel my best path at this point is to walk away from the 40s and put my time and money into the 44s which ARE the ones i intend to use, when i venture down the new engine path, due to size overall and the difs noted which i consider upgrades/improvements.

k