Tim, the crackle/popping is a symptom of a lean mixture and is produced when you take your foot off the gas while the truck is moving in gear. Giving it just an 1/8 turn on the idle mix circuit cures the problem.
On the Offy intake I had to grind a tad off the firewall side of the heat plate and thinned the head on the manifold bolt to get a full range of movement of the throttle. I discovered (after the fact) that it would have been easier to substitute a piece of heavy copper wire (like is used to ground electrical boxes) to get the bends in the vertical stock throttle rod. Bending the stock steel rod is a real pain in the fingers. Once you get the copper (3/16") rod bent to allow a full range of motion, you could use it as a pattern to bend the stock steel rod.
Once you get the dual set mounted and ready to tune it's fairly accurate to use a short piece of garden hose to get them synced. I'm deaf in one ear and can't hear out the other and when I manufactured a pair of "hats" to adapt the carb tops to a unisyn, I found I was less than a 1/4 turn off. I made the "hats" out of some scrap sheet metal, duct tape and dumb-dumb sealer and although they aren't my proudest creation, they work for periodic checks. BTW....the sync hasn't changed in 5000 miles with the dual setup.
Tom's price on both the carbs is rock bottom. My son added a very similar Weber carb to his 258 Jeep and I think that carb alone was over three hundred bucks. When compared to $109.00 for a "rebuilt" Rochester from Azone with a sloppy throttle shaft, a warped air horn and a manual choke that was incorrectly assembled and wouldn't function.....the H/W and C/W carbs are a real bargain.
Just remember to add the Mr. Gasket adjustable regulator....and BTW...if you add an inline metal/plastic filter between the regulator and the carbs, you'll need to increase the dial setting on the regulator to 4-1/2 psi. The filters bleed off 1 psi according to my pressure gauge.
Dave
