Lean running 455 on 2 cylinders

[Swanny454]

Hello all, new to your forum. I have a 1974 Buick Estate wagon with a 455 in it. It is all original with the only change being dual exhaust. The car has the original carb that has been rebuilt from a very reputable guy where I live. It has new plugs, wires, distributor. I have been fighting with a very mild ruff idle and it just does not run as well as it should. I found #7 and #2 cylinders not firing. I pulled all the plugs(Bosch Platinums and 6 of them are nice and brown and seem to be running about perfect. #2 and #7 are almost brand new looking with no color and the platinum is still bright white. I did a compression test on all 8 cylinders and all have 150psi. I then pulled the valve covers to verify the rocker arms were intact and push rods there. All four valves are traveling as they should. I am thinking that those two cylinders are running lean but I am at a loss. I am thinking that maybe I have a vacuum leak but it idles decent beside the minor ruffness. Has anyone ever ran into this issue?

[gbsean]

funny that 2 and 7 are lean as the are diagonally opposite of each other but they are sequential in firing order..I would check to make sure they are getting spark first..

[71GSX455-4Spd]

Any chance you switched those two wires on the distributor cap by accident? 1-8-4-3-6-5-7-2. Right next to each other.

[Swanny454]

Both plugs are getting fire, I verified the firing order and the plug wires are on correctly. I pulled the carburetor off and when I reinstalled it after the rebuild was done on it I only used two gaskets. I used one base plate gasket, and the metal heat shield. I am thinking this is where I am having my vacuum leak, I believe there should be a gasket on both sides of the metal heat shield. I am going to work on it today and see what happens. Thanks for the ideas guys, keep sending them my way incase this isn't the problem. I also attached a couple pictures of it so you can see what I am working on. Car has 51,000 original miles. I bought it and it still had the original hubcaps and steel wheels on it. Only things I changed are the wheels and the exhaust. I kept all the original exhaust and the hubcaps and rims. It's only a wagon but someday it might be worth something since it is so original

[nick rabi]

Beautiful car!!

[Swanny454]

Thanks Nick, well I got it all back together and double checked my timing. It runs alot better with all three gaskets under the carb. I have picked up a clicking noise like a lifter tick but I had the timing advanced to far and it kicked back and broke the starter. Oh joy.

[gbsean]

Nice Wagon you should haul it out to the Big Boat Bash this year in Columbus

[Swanny454]

Haul it? No way....drive it??? Most definately. Will have to see how July goes. I sell school buses for a living and July/August get CRAZY for me