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Sprint Ambassador cap problems
Posted: Mon Jul 03, 2017 2:29 pm
by dursley92
I thought I would try fitting the Ambassador dizzy cap on my Sprint engine after reading about folks using them as an alternative but found it to be a very tight fit under the inlet manifold. I finally got it on there complete with a new red rotor arm and some new 8mm leads and all seemed good. I had checked the timing before and after to be sure and it was spot on. A quick test up the road and all was good. Next day however I did a slightly longer run of about 10 miles and it started to develop a mis-fire. It began at mid to higher revs but got gradually worse with some spitting back through the carbs as well so the last mile home was a bit nervous. There was nothing obvious to see and as I had just filled with fuel I checked the fuel to be sure there was no contamination and that the pump was doing its job properly. All was fine here as well so it obviously must be something to do with the new ignition items.
Getting the new cap off was even worse than fitting it and the hot engine made the job even harder. To confirm the diagnosis I just put all the old cap, rotor and leads back on and the misfire was gone. It ran fine again and yesterday we did a 100 mile classic tour with the engine running perfectly.
My conclusion is to forget about the Ambassador cap option and to get a new remanufactured Sprint one from the Club to go with some new screw-in leads. At least I will be able to work on it without too much difficulty.
Re: Sprint Ambassador cap problems
Posted: Mon Jul 03, 2017 7:30 pm
by tony g
If the red rotor was not from Distributor Doctor
http://www.distributordoctor.com/ it may be rubbish, he led the way with the "red" caps and there have been a lot of rubbish copies. My cap is the same style as yours but i seem to have more clearance, maybe cap is suspect too if all leads are making good connection?
Tony
Re: Sprint Ambassador cap problems
Posted: Mon Jul 03, 2017 10:19 pm
by Galileo
Sure the vacuum unit is further towards to camera on mine, and that would make the cap easier to fit, or one of our timings is way out! The dizzy being on a worm drive can be put in different positions, maybe that's why?
Re: Sprint Ambassador cap problems
Posted: Tue Jul 04, 2017 7:27 am
by tony g
I looked at mine this morning and my cap looks a lot shallower than the one pictured, loads of clearance too. Clip on the engine side side causing swearing and temporary burns though
Tony
Re: Sprint Ambassador cap problems
Posted: Tue Jul 04, 2017 9:34 am
by cleverusername
dursley92 wrote: ↑Mon Jul 03, 2017 2:29 pm
I thought I would try fitting the Ambassador dizzy cap on my Sprint engine after reading about folks using them as an alternative but found it to be a very tight fit under the inlet manifold. I finally got it on there complete with a new red rotor arm and some new 8mm leads and all seemed good. I had checked the timing before and after to be sure and it was spot on. A quick test up the road and all was good. Next day however I did a slightly longer run of about 10 miles and it started to develop a mis-fire. It began at mid to higher revs but got gradually worse with some spitting back through the carbs as well so the last mile home was a bit nervous. There was nothing obvious to see and as I had just filled with fuel I checked the fuel to be sure there was no contamination and that the pump was doing its job properly. All was fine here as well so it obviously must be something to do with the new ignition items.
Getting the new cap off was even worse than fitting it and the hot engine made the job even harder. To confirm the diagnosis I just put all the old cap, rotor and leads back on and the misfire was gone. It ran fine again and yesterday we did a 100 mile classic tour with the engine running perfectly.
My conclusion is to forget about the Ambassador cap option and to get a new remanufactured Sprint one from the Club to go with some new screw-in leads. At least I will be able to work on it without too much difficulty.
The Ambassador cap allows the cheap and effective britpart electronic ignition mod. I see no reason why it shouldn't work, it is simple ye olde technology. As long as the rotor arm and cap match all should be well.
I think you just have a duff part.