I've owned this 1972 MGB GT since 1987, having rebuilt it from scratch.

When I get around to it, I'll add some piccies and details of the rebuild.

It's still in my possesion and I fitted a new engine in 2005-2006.
Since the orginal rebuild, I'd never been happy with the engine as it would intermittantly backfire. I spent so much time trying to resolve this, took it to numerous 'specialists' and eventually put it down to 'just the way it is.

Anyway when I fitted the new engine, I assumed that this would resolve the problem, especially as I'd opted to update the ignition with a Magnatronic system.. it didn't... and the running was loads worse.
I really couldn't be bothered to spend loads more time on this, so I decided enough was enough and I needed to find someone who really knew MG engines and would resolve this for me once and for all.
Enter Peter Burgess in Alfreton.... I'd seen various articles in MG Enthusiast and Enjoying MG magazines which mentioned Peter's expert touch, so I gave him a call and arranged to take the MG over there.
Within minutes, Peter had whipped the dashpots off the SU carbs and said that there was something not quite right with the rear one. The jet was not moving freely and it was not obvious why this was.
At this point, Peter said to me "Right, you take the carbs off.. see you in a bit" and off he went explaining that he was happy to do the work but that obviously he'd charge me. So spanner in hand, I set to it. I'd stripped this car down so many times, that I was happy to do this. Peter was back in about 10 mins and I, secretly, think he was surprised that I'd already whipped them off !! :o)
But when we checked over the carbs on the bench the jets moved freely, leaving us to assume that something in the linkage must have been causing the problem, so I re-installed the carbs, checking the jets continually while refitting and all was well until I managed to catch the front carb's fuel feed pipe (the one that goes to the jet) and out of the jet assembly it popped.. arrgghhh!
So off with the carbs again and when we looked at the fuel pipe and jet assembly, we could see that the rubber 'olive' that is supposed to secure the fuel pipe was half blocking the jet.
Straight away, Peter said, "Well that was lucky.. I think we've found the original reason for the backfire". With the front carb fuel feed being partially blocked, it was being starved of fuel when the car was being driven.
I can only assume that the problem with the rear carb was down to when I refitted the carbs after fitting the new engine but we never found out what had caused the jet to jam.
Peter refitted the fuel feed to the jet which was a tricky job (I may need to change the jet assembly if it gives me anymore problems) and then we fired her up. I was pleased to see that the MG was setup just about right. Peter put her on his rolling road and did some final adjustments but didn't want to push it too much as the engine hadn't been fully run in.
I can honestly say that the MG runs better than she ever has and I can only blame myself for the problems as it was me that rebuilt the carbs 18ish years ago!!!
So massive thanks to Peter ... I was there for most of the day, had the MG fixed by somone who really knows what he's doing, had both the MG and Saab run up on the rolling road, was supplied with tea and after all this Peter charged me such a reasonable fee that I would recommend his services to anyone... absolutely fantastic.

THANKS PETER!! (http://www.mgcars.org.uk/peterburgess/)