MG MGB and MGB GT Tech Talk
'71 MGB-GT with 2 HS-4's and a 25D distributor. All the primary wires, cap & rotor were replaced last year, and decent tune as possible until I get the carbs rebuilt professionally. Was running well last week, now sounds like it's missing. Is the clamp on the dizzy prone to loosening-up? Thought I'd ask before I take the spanners to it...
Could be a number of things. Fouled or dirty plug(s), low damper oil, loose wire, bad Pertronix, carb mixture / balance, etc. Sure the dizzy can loosen and move, but it's that is far from the most likely cause in my opinion.
Well, put a timing light on it and check to see if it is the same as when it was running ok.
RS
the clamp can be improperly postioned and the dist can slip, effectively moving. I've seen this over and over again.
clamps get bent out of shape and installed upside down and are usually just cranked down hard rather than properly placed and snugged. This breaks the distributors too.
Rather than try to reuse a badly distored clamp, a new one is what I'd suggest. they are cheap.
Hey Jim,
Might want to check the plate inside of your dizzy. I had a funny issue where the plate got disconnected from the vac advance, allowing the points to wander 25 +/- degrees. I had Jeff fix it when I sent him my dizzy over the summer, but left unattended, it can cause an engine failure. Best way to check it is to see if the points move around.
He'll fix it for you if you send it up to him, it was well worth the money. Might be able to do it yourself too but he puts a quick tack weld and it fixes the problem permanently.
-Roy
