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907 engine ignition help....

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Hi, Due to my original points distributor having a faulty vacuum advance, I thought I would upgrade to an electronic system. I found a complete new distributor from Simon's Best British Classics on Ebay, and have had it in the garage for a couple of months awaiting fitting.

Yesterday i decided to fit the new distributor, and eventually (after some misunderstanding with the wiring instructions!) got the engine started. The "only " issue now is that once I dynamically timed the engine, it is not firing on No 2 cylinder (which it was with the points system). I have fitted new leads and cap, tested that there is a spak at the plug, (which there is) but no joy. The engine starts ok, but is obviously sounding rough. When you pull off the number 2 lead, there is no change. Pulling off any other lead stops the engine. I dug out an old Colourtune kit, and can see the spark, but no ignition in the cylinder.

Any ideas? The only issue I had with fitting the new distibutor was that it was a mirror image of the original part. I re-arranged the leads to compensate. I can't think that there would be any scenario where I could be so far out on the timing that it would run ok on 3 cylinders, but not on number 2? Or am I missing something?

Any suggestions greatley recieved!!!


Chris :censored:

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Since the other three are firing, and you can see a spark on the problem one, the first assumption I would make is that you are the victim of an unfortunate coincidence, and that something else has gone wrong with spectacular timing(!) Are you sure you're getting fuel to that cylinder? What's the compression like? Can you quickly fit the old dizzy as a control test?

Is there any (new) distributor orientation that will make all 4 fire?

British Fart to Florida, Nude to New York, Dunce to Denmark, Numpty to Newfoundland.  And Shitfaced Silly Sod to Sweden.

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Thanks, just tried the compression, and it's near as dammit the same as the others. Didn't check fuel but as the plug was wet and I was getting the odd blow back through the carb, I think that was ok. Must be the timing, so will refit the original and try it again!


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Double check your firing order. On a four cylinder engine, if you've set up 1-3-4-2, instead of 1-4-3-2, you will run, but the #3 & 4 will be on the wrong cycle when spark accures. It's suprising how well some engines will run so configured... depends on the cam events and amount of overlap. I'm almost certain that if you swap those two, you'll fix the issue. If not, I'd reinstall the original cap, it could be cross-firing. Even on a new cap, a tiny, often invisible, crack can cause a crossfire.



Edited by frommerstop
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