IGN timing revisited

Post by **deepdale** » 22 Jun 2006, 12:14

I have finally got my CU running after a full strip down and re build. It starts straight away but is a bit lumpy mainly i think due to the carbs needing a fine tweeking ( cyls 3 and 4 are not quite right).
ANYWAY I have a strobe timing light and when i point it at the timing marks to set it at 7.5 deg BTDC the paint mark i put on the v belt pully is a bit of a blurr and about an inch long which i have never seen before on other vehicles. (not till you rev em anyway)
I have a suspicion to what it may be but i dont want to put words in ya mouths. Any ideas??
Ta

Post by **toomanytoys** » 22 Jun 2006, 18:50

could be the mech advance in the dist sticking/broken spring etc.. or the vac advance retard unit not good?
Oh.. have you "bypassed" the ignition stabiliser idle thingamy? (black box with 2 plugs on the bottom) that might throw the timing light about

Post by **cumbriankeith** » 22 Jun 2006, 18:53

If you have the standard dual vac dizzy and leave the pipes connected then the idling timing should be 5 ATDC. With the retard pipe disconnected and plugged it should be about where you are. What idle are you at? Does the timing advance about 8 degs when you open the throttle from idle? Is the vac capsule good and leakfree?

The fuzziness of the image you're getting could be play in the system - eg due to worn diz shaft or lack of any/proper spring taking up the play in the diz drive from the camshaft. Probably some others like sticking mechanical advance stuff. I'd strip/service the diz anyway.

BTW lots of useful data here

Post by **deepdale** » 29 Jun 2006, 19:27

Thanks for your suggestions. I should have mentioned that the electronic ign system has been replaced with a conventional system ie points and the likes!! I have already had the dizzy apart and it appears to be in order. The vacuum chamber is also ok and can be seen moving the plate inside with a good suck!!
My idea was that the condensor may be goosed. i was once told that they in effect clean up the spark to produce a sharper more concentrated blast. Dunno if this s right?

Post by **toomanytoys** » 30 Jun 2006, 06:59

points is a backward step...
I would see what model number dist you have.. it could be a beetle one, which is all wrong..
The type 4 engine likes lots of initial advance.. and a beetle one doesnt give that..

Someone on here must have a good complete std dizzy set up for sale... !

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IGN timing revisited

IGN timing revisited

CU timing