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Teknikle questions
http://www.international2cvfriends.com/forum/viewtopic.php?f=7&t=5487		 Page 4 of 4
Author:  citroenboat [ January 6th, 2015, 2:32 pm ]
Post subject:  Re: Teknikle questions
Right, thanks to Russ for loan of the compression tester I now have some results.
First I did a test cold, before trying to start the engine, to see if there was a big difference between the pots to account for starting on only one, no, both showed approx 115psi.
Ran round the block - in the car, not me, on legs, perish the thought - to warm it up and then did the test properly (filter off, carb wide open, etc.) got 90psi on the right one and 100psi on the left. Hmm... What should they be please, I couldn't find values in Haynes, or any other manual I have and best I could find on here was Ken 'thinking it should be about 120 - 130 psi' - which should be gospel, right? :D
Ok, next I need to check that the tappets aren't tight & then to confirm that reading, I ground the valves & the head in last time I messed with this engine so they should be ok but I will look... and oh b*gg*r it's now raining...
Author:  citroenboat [ January 16th, 2015, 4:27 pm ]
Post subject:  Re: Teknikle questions
Valve gaps were fine so it isn't that.
Ring gap on the spare engine is .63mm so that's duff too, looks like a barrel & piston set then...

Cured the 1 cylinder starting 8-) - threw out the 123 & put points back in :D

Another question. The static advance is different on the 425, but is the dynamic advance the same for that and the 602? Reason I ask is I just put the first advance mechanism I laid my paws on in. Then I noticed this:
Attachment:
bob weights.jpg

If the weights are different does this affect the advance? Are there differences in the centre 'lump' of the advance mech. too? Did I put the wrong one in?! It runs ok but it occasionally 'spits' and misses, no power of course tho it feels livlier than on the 123, but that's probably just wishfull :lol:
Author:  chevrons2 [ January 16th, 2015, 5:26 pm ]
Post subject:  Re: Teknikle questions
citroenboat wrote:
Valve gaps were fine so it isn't that.
Ring gap on the spare engine is .63mm so that's duff too, looks like a barrel & piston set then...

Cured the 1 cylinder starting 8-) - threw out the 123 & put points back in :D

Another question. The static advance is different on the 425, but is the dynamic advance the same for that and the 602? Reason I ask is I just put the first advance mechanism I laid my paws on in. Then I noticed this:
Attachment:
bob weights.jpg

If the weights are different does this affect the advance? Are there differences in the centre 'lump' of the advance mech. too? Did I put the wrong one in?! It runs ok but it occasionally 'spits' and misses, no power of course tho it feels livlier than on the 123, but that's probably just wishfull :lol:

I've got a tool/gauge for checking the centrifugal advance, if you want to borrow it Mike. It's a copy of the original Citroen tool and has different divisions on the gauge-part, for the different engines.
Author:  citroenboat [ January 16th, 2015, 5:47 pm ]
Post subject:  Re: Teknikle questions
Cheers Daras, that would be a useful. Having the right one in might make a difference!

Just noticed ECAS are selling the long weight advance bob weights as being for post 70 M28 so that answers that I guess...
Author:  ken [ January 16th, 2015, 9:42 pm ]
Post subject:  Re: Teknikle questions
Are you sure the valve clearances are correct?
Usually, the 'hot' value for a compression reading is slightly higher than that for a 'cold' engine; the lower reading(s) you got suggest that the valve clearances may be too tight.

The amount of centrifugal advance on 425 engines is less than that on the later 602 engines, you'd probably be best using a strobe to check the setting at full advance.
Depending on whether your engine is an A53 or an A79/0, somewhere around 36* total advance shouldn't be too far off.

It certainly looks as though the advance weights which are fitted at present aren't correct, since the weights are wedged against the 'full advance' stops.
The earlier points cam has a longer dwell and it's got a profile which is more 'pointy' than the later one...
Author:  citroenboat [ January 16th, 2015, 11:19 pm ]
Post subject:  Re: Teknikle questions
Thanks Ken, yes I noticed there appear to be differences in the 'pointyness' of the points cam. That pic is actually the M4 engine, I don't recall what ignition it had when I got it but clearly that is a late bob weight with a 'blunt' cam, so wrong. Every day a skool day! I think I put a pointy cam and small weights in the 425, best check...
Couldn't find a points cam on ecas today, sure there was one last ime I looked, for about the same price as a 123...

Will check valves again; I set the exhaust with inlet fully open and vice versa is that wrong?
Author:  ken [ January 17th, 2015, 1:26 am ]
Post subject:  Re: Teknikle questions
'fraid so, the rule is to 'adjust the valve clearance for the valve which is on the opposite cylinder to the one which is fully open'... :(

So,
n/s exhaust open, set o/s exhaust,
n/s inlet open, set o/s inlet,
and so on.

Anyhow, won't you be able to 'borrow' a points cam and weights from Sam's M4 museum? ;)
Once you've got the correct combination of bits, the points cam should have a small amount of slop/slack in its 'at rest' position, with the weights moving outwards to contact their stops when you twist the points cam anti-clockwise.


citroenboat wrote:
Thanks Ken, yes I noticed there appear to be differences in the 'pointyness' of the points cam. That pic is actually the M4 engine, I don't recall what ignition it had when I got it but clearly that is a late bob weight with a 'blunt' cam, so wrong. Every day a skool day! I think I put a pointy cam and small weights in the 425, best check...
Couldn't find a points cam on ecas today, sure there was one last ime I looked, for about the same price as a 123...

Will check valves again; I set the exhaust with inlet fully open and vice versa is that wrong?
Author:  citroenboat [ January 19th, 2015, 3:32 pm ]
Post subject:  Re: Teknikle questions
Right done that, exhausts were slightly tight but not enuff to effect it badly. I knew it was done opposite, can only blame senility... :oops:
Author:  lpgo [ January 19th, 2015, 6:18 pm ]
Post subject:  Re: Teknikle questions
citroenboat wrote:
Right done that, exhausts were slightly tight but not enuff to effect it badly. I knew it was done opposite, can only blame senility... :oops:


Did you set your valves at a hot engine... you should with these old flat head engines...
Author:  citroenboat [ January 19th, 2015, 9:20 pm ]
Post subject:  Re: Teknikle questions
Argh!!!! :evil: No Geo, cold, like I was always told. But, every day is a skool day. Why hot on the old engines & not the new? I assumed that cold was the way to do it as it was a constant while the expansion with hot can vary with how hot....?! Or am I barking up the wrong tree again?
As always it is a pleasure to learn from you chaps, thank you.
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