Howlor
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| posted on 14/7/09 at 08:15 PM |
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Ignition Timing can someone explain
Evening All,
I have been setting the ignition timing on the VW camper 1977 1600. I have done some reading and it all seemed clear but there are some bits that I
don't fully understand.
I first set it statically, I moved the V notch on the crank pulley until it was 7.5 degrees anti clockwise so BTDC. I then put a bulb across the coil
and earth. I moved the distributor until the bulb went out. Then checked it by moving the crank pulley and the light went out as I got to 7.5 degrees
before TDC. Bingo.
I then used the timing light and the V was in line with the crankcase split. This is correct to what I have read.
Why though if the notch is TDC is the stobe firing when in line with the split? I would have thought that as per the static set up the V notch would
have been 7.5 degrees to the left ie BTDC.
As it is the strobe is sort of saying that the spark for no. 1 is firing on TDC. 
Just for my own sanity can someone explain.
Thanks,
Steve
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britishtrident
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| posted on 14/7/09 at 08:19 PM |
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I suspect something turns (either the crank or dizzie) the oposite way from you think does.
ie you set the timing 7.5 degrees ATDC then when the engine starts you get 7 degrees or so advance.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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blakep82
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| posted on 14/7/09 at 08:27 PM |
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i have no idea, so i can't disagree with BT, but i'm not sure how that makes sense. if anything is set to anything but TDC, it
shouldn't fire at TDC?
only thing i can suggest is try turning it a bit further and try again. or rather, turn the dizzy while the engine is running and see what happens to
the mark on the crank until you get the required advance.
isn't static timing just to get really close to start with, so that the engine will fire easy enough, and then the timing while the engine is
running is done to get it spot on?
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Jasongray5
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| posted on 14/7/09 at 08:31 PM |
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quote:
Originally posted by blakep82
isn't static timing just to get really close to start with, so that the engine will fire easy enough, and then the timing while the engine is
running is done to get it spot on?
This is what I done on a Pinto campervan. Went from a spluttering wreck to a good goer!
How hard can it be?
http://www.flickr.com/photos/33261515@N03/sets/72157611049241239/
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blakep82
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| posted on 14/7/09 at 08:38 PM |
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^ so if it'll run easy enough at TDC, get in amongst it and start fiddling with the dizzy till you get 7.5 degrees or whatever you need
my engine's on megajolt, running a nice 10 degrees just now on the edis only. can't wait to get the MJ in and start making it do stuff
with the laptop connected 
[Edited on 14/7/09 by blakep82]
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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rusty nuts
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| posted on 14/7/09 at 08:38 PM |
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Turning the engine against it's normal direction of rotation will introduce slack into the distributor drive and always gives an incorrect
timing .
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Howlor
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| posted on 14/7/09 at 08:41 PM |
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Yes I agree, what it said was turn it well past then come up to the trigger point again so you get rid of any play.
It runs really well as it is set now, just can't understand why the static and the dynamic strobe should point to different marks!
Steve
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blakep82
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| posted on 14/7/09 at 08:43 PM |
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never done static timing with a little lamp on the coil, wouldn't have a clue how accurate it might be.
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Howlor
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| posted on 14/7/09 at 09:11 PM |
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It's ok I've sorted it out in my mind!
The V in the pulley is actually 7.5 degrees BTDC. Therefore this should line up with the case split when on the strobe. For the static check I read
that you need to move the notch until it is 7.5 degreed BTDC. I was using the V notch which is not TDC!
So the 2 methods now come out bang on. Right i can now sleep easy.
Thanks,
Steve
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blakep82
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| posted on 14/7/09 at 09:14 PM |
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ah, is there a couple of notches then? i have seen a pulley like that before.
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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Howlor
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| posted on 14/7/09 at 09:45 PM |
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Yep one small one that looks like a random hacksaw cut and a V notch. I thought the V notch was TDC, it turns out that it is 7.5 degrees BTDC. The
small notch is TDC!
Thanks,
Steve
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