DavidM
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| posted on 22/8/10 at 03:01 PM |
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Crossflow Timing
I've set my crossflow to 10 deg BTDC static, but want to check it with a timing light. Can someone tell me what the timing should be at idle,
it doesn't say in the Haynes manual.
Thanks
David
Proportion is Everything
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GeoffT
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| posted on 22/8/10 at 03:13 PM |
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Not sure what the recommended number is, but from memory my crossflow seemed to like quite a lot of static advance, something like 15-17 deg.
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britishtrident
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| posted on 22/8/10 at 04:14 PM |
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A lot of static ting on an Xflo will cause major starting problems especially when warm.
[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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ernie
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| posted on 22/8/10 at 07:10 PM |
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Our race ones are approx 36 at 4000 revs
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David Jenkins
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| posted on 22/8/10 at 09:36 PM |
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It depends on which size x-flow you've got! The following figures are from the Haynes manual:
1.1 = 6 degrees BTDC
1.3 low compression = 12 degrees BTDC
1.3 high compression = 10 degrees BTDC
1.3 (all other versions) = 6 degrees BTDC
1.6 = 10 degrees BTDC
This is static timing, used when setting up a mechanical distributor and would be checked with the dizzy's vacuum pipe disconnected (and
plugged!).
My x-flow has Megajolt ignition, so I've set the cranking ignition timing to 8 degrees BTDC, to give the starter motor a better chance of
turning the engine over. Once the engine's running the MJ map takes over.
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lotustwincam
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| posted on 22/8/10 at 09:44 PM |
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I agree with all the above answers.
On a Xflow its normal to keep increasing the advance at idle speed until the engine speed doesn't increase any further. Normally this will be
around 12 - 18 degrees, but it will depend on the state of tune of your engine.
Next check and see if the starter motor can actually turn the engine over with this amount of advance, This will depend on the quality of your
battery, cables and motor. Back off the advance until the engine turns over. (Before changing to MegaJolt, I had to upgrade by battery cables to get
the engine to turn over with the most suitable advance. Now using cables from an arc welder.)
Finally check that the maximum advance is "all in" around 3.500 to 4,000 RPM and is no more than 36 degrees. Somewhere on the net you will
find information on modifying a distributor to restrict max advance.
If you are using a standard dizzy, with mechanical contact points, check for wear in the shaft. If there is side play in the shaft, your ignition
timing will be all over the place.
Drew
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procomp
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| posted on 23/8/10 at 12:36 PM |
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Hi
Set engine at TDC accurately and check your pulley marks are correct. It's not unusual for the pulley marks to be up to 4 degrees out. !!!
Cheers Matt
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britishtrident
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| posted on 23/8/10 at 01:23 PM |
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When setting the timing by the tradditional by ear method with the Engine at idle the procedure is to advance the ignition until you get the highest
idle speed (you may need to re-adjust the idle speed downwards when doing this) then retard the ignition until the idle speed is stable ie not
hunting. Hunting is when the RPM continually rises and falls by 50 rpm or so at idle.
After that you have to do three important tests.
(1) When the engine is hot road test for "pinking" by letting the engine pull at full throttle in a high gear from low to medium RPM.
This test is usually best climbing on a slight hill.
(2) Check the engine will start especially when hot without kicking back against the starter.
(3) Using a strobe check that the adavance at high RPM dosen't exceed 36 degrees ---- for mechanical reason this is the practical limit of
ignition advance on most engines.
Ford Kent distributors generally have only 10 degrees centrifugal advance built in ie 20 degrees at the crankshaft.
This is one of the reason why Fords had a seriously bad reputation for undependable starting in the 1960 & 70s.
Any Xflo distributor benefits from being modified to give a a few degrees more centrifugal advance at high RPM as this will allow the dizzie to be
set to give less static adavance reducing starting problems.
[Edited on 23/8/10 by britishtrident]
[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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