Agriv8
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| posted on 9/4/07 at 03:59 PM |
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Wanted Suggestions for replacement timming gun
Right.
the long and the short of it is that neither of my timing guns like my waisted spark coil ign system.
anyone sugest a suitable gun thats readilly available that is known to work with a waisted spark system
Many thanks
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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rusty nuts
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| posted on 9/4/07 at 05:02 PM |
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Used my Snap On digital timing light today with wasted spark , yes you do get double the rpm as it reads the number of times the plug is fired ,
simple to halve the reading . The timing is not altered with wasted spark . If funds will run to a Snap On light then I would recommend them . PS How
often will you use one?
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jollygreengiant
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| posted on 9/4/07 at 05:19 PM |
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quote:
Originally posted by rusty nuts
Used my Snap On digital timing light today with wasted spark , yes you do get double the rpm as it reads the number of times the plug is fired ,
simple to halve the reading . The timing is not altered with wasted spark . If funds will run to a Snap On light then I would recommend them . PS How
often will you use one?
I'll second that my snap-on gun is the DB's.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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chriscook
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| posted on 9/4/07 at 06:32 PM |
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The timing value show double with the snap-on lights that read double rpm on wasted spark.
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Chaz
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| posted on 9/4/07 at 07:11 PM |
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What does a timing gun do???
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rusty nuts
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| posted on 9/4/07 at 07:54 PM |
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quote:
Originally posted by chriscook
The timing value show double with the snap-on lights that read double rpm on wasted spark.
Don't think so .It only flashes when plugs are fired and as it fires every revolution instead of every other revolution , as with a
distributor, it will show double the rpm but not double the amount of advance
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chriscook
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| posted on 9/4/07 at 08:05 PM |
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But the flashing every rev instead of every other it thinks that 360degrees is actually 720degrees so it doubles the timing readout too.
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Agriv8
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| posted on 9/4/07 at 08:19 PM |
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Rob - The main man behind VEMS suggests one without the Dwel device as can cause problems ( I suspect that the Snapon one is EXPENSIVe enough to deal
with this )
so the drapper one is a possible any others. So as its waisted spark assume I am going to get two flashes ( first at 0 and another at 180 )
Further sugestions welcolm
Regards
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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rusty nuts
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| posted on 9/4/07 at 08:32 PM |
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Wasted spark fires plug EVERY 360 degrees so would show the same advance. It would NOT show double the advance BUT would show double the rpm. Read
David Walkers book on engine management !
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DIY Si
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| posted on 9/4/07 at 08:38 PM |
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Rusty's right. All that happens is you get 2 flashes per 720 rather than 1. As long as you double or half the number of flashes, then no change
will be seen. If it went to 3 per 720 degrees, then you'd have issues. As it is, the light falls on the same mark twice, rather than just once.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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chriscook
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| posted on 10/4/07 at 08:39 AM |
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I'm sorry but I disagree from experience and also if you work it out.
I'm talking about the type of light that has button on it which advances/retards the flash to align the timing marks and it displays an advance
figure for the amount of advance it is using. The light I was using was quite an old snap-on light - the newer ones understand wasted spark and work
properly.
However, for the older type If say you are running at 10degrees advance on a NON wasted spark ignition at 3600rpm (to make the numbers a bit easier).
Then the advance in terms of time to delay the flash is:
3600rpm = 60rps = 21600degrees/sec
10degress => 0.46ms
Now with wasted spark the light does not know it is wasted spark so reports 7200rpm or 43200deg/sec.
The time delay is still the same to align the timing marks which is manually set by the user at 0.46ms. Now 0.46ms at 43200deg/sec means:
(0.46/1000)*43200=20degrees
The time delay is the same but because the engine speed is read as twice as fast it calculates the advance wrong also.
FWIW I have read Dave Walker book on Engine management 
[Edited on 10/4/07 by chriscook]
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martyn_16v
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| posted on 10/4/07 at 08:51 AM |
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If you set the advance on the gun to zero and physically mark a pulley at 0,5,10 deg etc and read the marks you should be OK either way i'd have
thought.
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DarrenW
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| posted on 10/4/07 at 09:40 AM |
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My digital Snap-on advance timing light works very well with my MJLJ install but you do have to half the advance and rpm readings.
Got my light off ebay for about £35, twas a good investment.
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02GF74
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| posted on 11/4/07 at 07:03 AM |
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I have a locost DIY version - uses a xenon bulb with power supplied by a 12 V transformer wired in reverse  bulb housed is in an old bicycle lamp
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