Triumph Repair: Triumph Spitfire Refuses to Idle!, carb rebuild idling

Question
Hi there, I wonder if you have any ideas? I've bought a MKIV Spitfire that has been fitted with a '79-'80 1500 engine and o'drive g'box. The following repairs have been necessary, and all have made some improvement:- (not in order) Renewed fuel pump; renewed manifold gasket; stripped and cleaned carbs; fitted non-waxstat jets; adjusted valve gaps; renewed spark plugs; fitted correct(new)distributor and leads; renewed battery; adjusted ignition timing; carried out compression check - satisfactory. Help. The engine seems to pull fine but will only idle at over 1000rpm and even that is erratic! It's been a few years since I last worked on my own cars, but I think I've covered all the usual. Any advice greatly appreciated.

Answer
This is fuel starvation, given how you have described.

Check the intake manifold for leaks (spray starting fluid around the gasket surfaces
-Re-rebuild the carb.
    -Check float level
    -use compressed air & small dowel to clean & blow out all the tiny passages; they are easily clogged
    -recheck the air valve diaphram for a pinhole leak or tear

When this has happened to me, it was passages in the carb being plugged.

The other option is missing on one cylinder.  Use your timing light and make sure each lead has a consistent flash.  If that is OK, then the issue is almost assuredly fuel.