Ok, here is my two cents on this. I have run a weiand tunnel ram on my small block for over twenty years. I originally started out with two 8007 390 single inlet carbs mounted inline. These are vac secondary carbs and it ran well on the street with plenty of power. I then really got into the local drag racing scene and changed out the holleys for two predators. BIG mistake. After spending cubic dollars to have these carbs modified by predator the car never ran right. Big time rich and high idle.
swiched to two 600 holleys inline and didn't notice any improvement over the 390's.
Finally switched back to the 390's, this time sidemounted with center hung bowls. Works great, looks trick. I run the mr gasket stret scoop with no hood.
My engine specs are: 355, full ported 292 heads,msd dist with vac advance hooked up, comp cams xtreme energy 274 cam, hooker 1-3/4 headers.
I run a Dynamic Racing turbo 350 full manual with a 3800 stall converter. I have 4.10 gears and 275-60-15 Mccrearys.
The key is to adjust the idle using the primary idle screw and the secondary stop under the carb. Power valve are 4.5 and out of the box jetting. I don't have the vac cans referenced to each other and have a crane adjustable vac advance. Timing is 36 deg all in by 2800, initial at 12. I have driven this combo many mles without issue.
If you need more info contact me at [email protected]