Weber carb set up help, Jetting seemed to help but still slight popping/backfire Options

[North Coast Jim]

Just finished a new 2 liter engine build with Webcam for carbs installed.
New Raby heads, Hoffman Eng, are used. New 44IDF Webers installed with cross bar linkage. Valve lash to spec and timing is spot on. Carbs are synched. Continue to hear a slight popping from only the pass side carb at partial throttle positions. Car starts and idles with plenty of power thru acceleration, but who knows I haven't driven one in over 25 years. It's a hoot to drive except for the Issue. Played with jetting to no avail. Any Carb guru's out there able to provide input to solve this dilemma.

(IMG:style_emoticons/default/headbang.gif) (IMG:style_emoticons/default/confused24.gif)

[Mark Henry]

To me, cable or not, you still have one carb opening slightly before the other. I go to great pains to make sure the throttles are opening at the same time and rate. Number one with a crossbar or center pull is to make sure the arms are as close as you can get to 90 degrees to the throttle shafts. Then there must be zero slop in the linkage. I do not use a linkage with one CCW threaded shaft I feel this causes more problems then it solves. I use high quality rod ends that alone cost me $50 for 4 .

I sync the carbs with one arm off, I never have to sync at any other position, because again I feel it creates more problems then it solves. Then I carefully bend the one arm (that's off for sync) till it goes in like butter, absolute zero effect on the sync/linkage. If I'm going out of sync at higher RPM then it's time to start over, as I still have a linkage issue.
Also I've found I have the exact same linkage sync issues with programmable EFI and ITB's, you can't blame that on jets.

One of the reasons I like the center pull linkage is I can shape the arms (to get my 90 degrees to the throttle shafts) to help eliminate the geometry issues caused by the offset of the carbs. With a slight bit of slack on the throttle cable engine expansion is not a problem. Even if you get the geometry perfect on a hex bar linkage, the bar itself and bushings tend to twist.
The T4 has a huge intake port offset compared to the T1. The only crossbar linkage that I have any use for is the Gene Berg unit for the T1, unfortunately you can't adapt it for type 4 use.

BTW the /6 has way less linkage/sync sensitivity, it acts more like two 3 cylinder engines ganged together, where as the /4 is very susceptible to even the slightest issue.