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MG MGB Technical - engine running poorly

Hi all I am new to board but mg owner for a few years I have a 73 b with an unknown engine the number plate just below plugs has been removed. The car has never run right I don't know where to set timing as it depends on engine numbers and without the proper timing I cant set the carbs! It has been running way too rich and mis fires. I have been trying to adjust timing by the way the car drives but to no avail. Is there another way to id the engine if not what is a good starting point for timing on a 73? The last owner said he put a mild cam in it 52? how would this affect the timing?
RHM Massie

No, timing doesn't depend on the engine number - it depends on the distributor number which is stamped on the distributor body - a five figure number starting with 4.

Tell us what that is and we can tell you what the timing should be.
Chris at Octarine Services

Chris is the expert, and a great resource for the board, he is too modest to post it here but his Octarine Services site is very useful
http://octarine.mywowbb.com/
It should not be impossible to get your car running well. 10 degrees static should be good starting point, and the jet/needle combination is important. It may be a good idea to get new standard jets for the 18V engine and some standard needles (all in the archive) and either set up using the factory manual (it used to be on the Yahoo site scanned in) or just go to a garage and get it set at idle. From there you can go onto haystack or mintylamb(archives again) and try some needles that allow more fuel at high revs to allow you to use the extra air the cam will flow when the scavenge effect kicks in. My car with a 270 cam can be set to run fine on 10 deg static and no 5s it just wont develop max power at high revs.
One small point, has someone fitted a "performance" vacumless dizzi? If so my advice is sell it someone who races and go back to standard.
Stan Best

Thanks for the input It would appear that it is a vacumless dist as there are no lines or places to hook up lines on the dist The number I saw stamped on it is 43DE 1576 and I also have a breakerless pretronics ignition on it.
RHM Massie

That should be 43DE4 41576

Not an MGB distributor.

I guess someone has fitted that to replace a faulty original.

The correct distributor for a 73 US car is a 25D4 41491 - with vacuum advance

For the 43DE distributor you will have to set the timing to 34 degrees BTDC at 3000 rpm and see how the engine runs at idle.

Chris at Octarine Services

Wow That is diffrent from what I was trying to set it at! Should I get a stock dist and run that? I am using the car for a weekend driver no racing. Do you have any recomendations for carb jets and needles.I will set the timing before I start changing that around.
Tanks Ralph.
RHM Massie

I set the timing and she still did not run right I found one of the carb needles bent slightly and the corisponding jet damaged the hole was worn out of round.The needles that were in it are aae. The car is still runing rich at idle but loses power under hard to moderate acceleration. What needles jets do you reccomend I have the after market dist and a mild cam a monza exauhst and stock air filters.
RHM Massie

This thread was discussed between 28/06/2007 and 03/07/2007

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.