Triumph Repair: 76 TR6 Runs poorly., head gasket replacement, stock cam

Question
I am currently working on a 1976 TR6, this vehicle over the past few years has been completely rebuilt from the tires to the top. The problem I am having now started after a complete tear down and rebuild of the engine. Engine was bored .040 over new pistons, rings, valve, valve seats, guides, new stock cam. You name it was replaced. Prior to all of this the engine ran rather smooth, burned a little oil, but was ok. Since it has been put back together it runs very bad. Idles rough, smells very rich. The ignition has been replaced with a pertronix coil and electronic ignition, new cap, rotor, plugs and wires. Ignition timing has been set repeatedly and is dead on. When the engine was torn down the carbs were not touched (it has dual Weber 32/36 DGV on it). Recently blew a head gasket replaced the head gasket and also put new plugs in it. After head gasket replacement readjusted valve clearance to .010 and engine still runs bad. Grounded spark and found the only cyl that had a change in rpm was 4. Loosened valves up to ensure they were closing fully, and it runs a little better. Grounded spark again and rpm change is now the same on all cyl. Removed plugs after doing the previous, and found cylinders 1,2 and 3 were all black, and 4,5 and 6 were not. Although I cant explain it I am leaning toward a problem with the carb for cyl 1,2 and 3. Checked cylinder leakage on all cylinders and all valves are currently closing, do have slight piston blow-by on all cyl. Also found cyl 6 is leaking in to the coolant passage. Possibly a bad power valve? Even though nothing was done with the carb from disassembly to re-assembly. Any other ideas would be very helpful.

Answer
Hi Corey,

If the 1,2 & 3 plugs were "flat black" it is for sure too much gas per air on the front carburetor. If they were "Wet black" that may or may not be the case.

If the plugs are flat black, It could be a choke or a power valve problem or a flooding condition. Either way the ONLY thing that can cause "flat black" plugs is a rich condition, nothing else.

Does it clear up at high RPM with no load? Did you run a intake manifold pressure test (vacuum test)?

I found that working in dealerships that all engines can be diagnosed with a compression test (or leak down test) then a vacuum test. That will rule out the engine itself. Then test the ignition by confirming the firing order, and timing and that for the most part eliminates the ignition (if you have access to a scope that is finished in 2 minutes)

Fuel must always be tested last. It is no use looking at fuel until it is confirmed that the combustion chambers are ok and that Ignition is in the correct order and at the correct time.

Too little fuel can always be tested by spraying starter fluid into the intake and flat black plugs and black smoke out the exhaust is 100% too much fuel.

let me know,

Howard