[HO455]

Thanks everyone for all of your support. Time to get some other things done on the WMB. Its out with the old carb and in with an even older carburetor. Something I've been wanting to do for a while now. We pulled the Edelbrock 1406 and installed a Qjet my buddy Karl rebuilt. It's a 78 truck carb we believe is off a 400. After installing it and checking for leaks. It fired right up but idled high. Although the mixture screws responded well the idle would not come down. The vacuum guage showed 20 inches of vacuum so we didn't suspect a vacuum leak.
After checking the timing and finding it to be ok, we were still unable to get the idle to come down below 850 in gear. We pulled the carb and checked the idle air bleed sizes in the base plate. They measured a whopping .120, a size more appropriate to a big engine with a lot of overlap in the cam, and not my little stocker. Took and tapped the holes and plugged them with set screws then drilled a .052 hole in each set screw. That got the idle down to 780 with good response from the idle mixture screws.
So off the carb came and a more complete examination of the idle circuit. After pulling the idle mixture tubes they were found to be .036's. Karl replaced them with a pair of .033's out of his magic box of spares. Once again more appropriate for a stock 350. Flipping the carb body over the idle bypass holes were tapped and plugged with set screws. They were not drilled out at this time but maybe later as things get more dialed in.
After reassembly and installation the idle was now around 700. Went for a little test drive and came back grinning. The throttle response was great, but I had no secondarys. Checking the secondary flapper spring found it to be quite tight. Loosening it up allowed the secondarys to open. For the first time since I have owned the truck I can tell when the secondarys open. Who hoo!
Time to put some miles on the truck and discover any other shortcomings or areas of improvement (like a choke). The choke stove we had didn't fit the 72 intake I had installed. From the size of the idle circuits the donor carb may have been a high altitude due to the large amount of air by passing the idle circuits. The carburetor number came out to a 78 350/400 which is right in the middle of the smog years when the manufacturers were struggling to pass emissions. It had to run enough to pass emissions, but running good wasn't as much of a concern.

The primary jets are 64's
The primary rods are B32's
The secondary rods are AR's

We noticed some irregularities in the timing at idle so a quick look at the idle weights reveled little except a well worn rotor center contact. A slightly used rotor seemed to solve the problem. Another thing we noted is with the timing set at 12* initial I am only getting 24 degrees total advance. We bumped it up to 14* to get a little better MPG, but distributor changes are required to get more advance.