Hey guys I can't seem to get the timing spot on on my mini. It's a recent rebuild with twin su's and electronic ignition. Going by the manual and bouncing a timing light onto the flywheel and setting it 5-10 degrees.
The car is rubbish! I assume I'm advancing it by turning dizzy to the right but when I do the marks totally disappear off flywheel and no idea where it's at but the car is heaps better.

It either backfires and splutters at low rpm or if I advance it more I can rev it to about 4500 and starts to backfire and pop. With it setup like this it's drivable but could be a little better.

Is there any other thing or way I should be doing to get it right??

Hi, I am assuming you do not have a timing light that has adjustable settings, where for instance you could set the light at 30 degrees, rev the engine and then the light shining at TDc would actually mean 30 deg total advance at those revs...this is the best way and setting timing at 28 -30 deg at say 3500 rpm is usually very safe.
There is another way ,but this is only a method to get it close , and then do it accurately
Rev the motor to about 3500 rpm, and then move the dissy clockwise until it runs the fastest, go a little more and it will slow down, go back to the fastest point and then go back anticlockwise about 2 or 3 degrees to try and make sure you haven't got too much advance.... this will get it running quite close ...but this is not a subsitute for getting the distributor professionally curved to suit the engine, and then most times they will advise setting it at 10 deg at idle This is all assuming the carby is correct and you don't have inlet air leaks, as this can also cause the backfiring..... to check for air leaks which is not hard to get with twin su, you can pour some water down over the inlet gasket area while the engine is idling ...if it speeds up you have air leaks
cheers Lindsay Siebler

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1965 Mk1 Cooper S restored
1970 Colt 1100F SS restored
2014 Mitsubishi Imiev fully electric daily driver
1948 Allard M coupe Olds 215 v8 project
1971 Twin cam Escort ex Uk championship winning rally car project

if you put in your location, someone might offer to come around and have a fiddle with it

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A bit more info will help.
What dissy are you running with and what internal dissy advance plates do you have? What engine and mods?
If you know what advance plates are inside the dissy you can workout an idle timing advance. A lot of dissys will have a 14 or 15 degree plate (28-30 crank advance) if you set the idle at 10 deg you can have 40 deg at high rpms giving you detonation issues. 28-32 max advance should be around the mark.
Were the carbies and dissy replaced at the same time?
I try and do one thing at a time to help with trouble shooting but if you have just had a rebuild this is easier said than done. Back firing out the carbies can be a timing issue or the carbies can be running very lean.

45d dizzy. motor is 40" over and that's it. I don't know anything about the dizzy advance plates. The carbys were ripped apart and rebuilt from scratch.