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Strobe timing - 2 marks ??
http://www.international2cvfriends.com/forum/viewtopic.php?f=7&t=3290		 Page 1 of 1
Author:  Bugster [ September 1st, 2011, 9:08 pm ]
Post subject:  Strobe timing - 2 marks ??
Hi, I hope this is the right forum.

I've never experienced this before but when using a strobe to check my 2CV timing I'm showing 2 tippexed ring gear teeth apart by 2 teeth. And I've only tippexed one. I found the one to mark by using the 6mm rod mentioned in Haynes. Probably best to look at the pic below which is a mockup but shows what I'm seeing. Does this mean one cylinder is firing 6 - 7 degrees after the other?

Also I put a smaller mark on the 7th tooth ahead of the first and when I rev to around 3000rpm I see two of those marks then occasionally get a misfire and they disappear and revert to the static marks before advancing again?

Any advice really appreciated thanks :)
Author:  Sean [ September 1st, 2011, 10:00 pm ]
Post subject:  Re: Strobe timing - 2 marks ??
Bugster wrote:
Hi, I hope this is the right forum.

I've never experienced this before but when using a strobe to check my 2CV timing I'm showing 2 tippexed ring gear teeth apart by 2 teeth. And I've only tippexed one. I found the one to mark by using the 6mm rod mentioned in Haynes. Probably best to look at the pic below which is a mockup but shows what I'm seeing. Does this mean one cylinder is firing 6 - 7 degrees after the other?

Also I put a smaller mark on the 7th tooth ahead of the first and when I rev to around 3000rpm I see two of those marks then occasionally get a misfire and they disappear and revert to the static marks before advancing again?

Any advice really appreciated thanks :)


yes - thats "scatter" caused by wear in the points mech or a camshaft that needs a tickle!

1, try taking the cam off and turning it 180* if its still not improved then this can actually be a case where new cam, and bob weights are needed especilly if the cam shows significant wear or scoring. If not but see below


2, the nose of the camshaft with the points mech spider is a push fit in the actual cam shaft and can work loose! tapping with a hammer and carefull! use of a punch can make it all line up spot on. Its one of the things we do on racers so the timing is spot on at 6Krpm ideally a dial gauge should be set up to see how far out the cam carrier is and this can be adjusted with a hammer and punch.....gently! if you dont have a dial gauge then a test bulb a'la Haynes and tippex on the flywheel can be used to judge the firing point and the nose adjusted accordingly

Timing,
the first mark you made is the static, mark round to the 7th and really thats the one you should be looking to make good to the datum on the bellhousing stud.

Sean
Author:  lpgo [ September 1st, 2011, 10:02 pm ]
Post subject:  Re: Strobe timing - 2 marks ??
This one is easy......... (in dutch) try to do it in English

Here we go. a 2cv is a 4 stroke engine this means that every 2 revelutions (of the crankshaft) a spark (in your'e case a strobe-blink appears. Because we have 2 cilinders each revelution a spark occurs one time the left cilinder sparks the next revelution the right one and so on...........

But the timing is done at the Camshaft and here comes the problem. The camshaft turns half the speed of the camshaft, for each cilinder there is a point on which it fires, so when there is a little play or crooke then both cilinders don't fire at the same point, therefor you see 2 marks with the strobe.

I've red somewhere how you can straigten this out, I try to find it and post it here.

I don't need it anymore because I run electronic ignition with marks at the flywheel.

p.s. All ignition systems which are mounted at the camshaft can have this problem be it original, 123, dgnition. and so on.


please read my topic;

viewtopic.php?f=7&t=3003


or see this vid http://www.youtube.com/watch?v=bOdvMAT6 ... er&list=UL



I hope it is clear for you otherwise I try to explain again :lol: :lol: :lol: :lol: :lol:
Author:  Bugster [ September 1st, 2011, 10:48 pm ]
Post subject:  Re: Strobe timing - 2 marks ??
Wow thanks for the quick replies Sean and lpgo :) At least I now know I'm not seeing double - was about to book into Specsavers :oops:

Right I shall get into the points box tomorrow and see what I find. I'll let you know and thanks again.
Author:  Bugster [ September 2nd, 2011, 9:33 pm ]
Post subject:  Re: Strobe timing - 2 marks ??
Well I've got into the points box and removed the cam. The points heel has worn the cam down by .0015". I tried fitting it 180 degrees from existing but under the strobe light it's just the same - double vision. So I checked out the ECAS website (sorry can we mention suppliers here?) for a new cam and balance weights and for the extra cost they suggest upgrading to a 123 electronic ignition so I've bitten the bullet and ordered one.

It was good getting into the gubbins of a 2CV again and I rapidly remembered the layout from when we had a 2CV back in the early 80s - I even had my ground down 14mm socket for the fan bolt still in my tool box. :o

Then I spotted the oil cooler which using a sheet of paper and a torch behind it looked completely blocked. I shot a long blast of brake cleaner through it but it made no difference so I removed it only to find you have to look through it at an angle and it was perfectly clear.

Another lesson learned then :oops: :)
Author:  lpgo [ September 2nd, 2011, 10:08 pm ]
Post subject:  Re: Strobe timing - 2 marks ??
They still have secrets after all these years don't they !! :P
Author:  Bugster [ September 2nd, 2011, 10:53 pm ]
Post subject:  Re: Strobe timing - 2 marks ??
lpgo wrote:
They still have secrets after all these years don't they !! :P


They certainly do lpgo - I'm really enjoying myself working on this great car. Thanks again for your advice and I'll report back when the 123 is fitted. ;)
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