quote:Originally posted by threadbare wallet
Whats wrong with copper core leads?
The HT lead resistance should not be too low for the following reasons....
If the lead resistance is low, when the plug fires, the energy from the coil is consumed very fast - the current at the plug will be higher but for a
shorter duration, some resistance in the system lowers the peak current but allows the discharge from the coil to be slower therefore a longer
duration spark is produced (this is what you need for decent combustion)
Very fast discharge and high peak currents can cause reflections in the HT leads, crossfire and ignition amplifier damage.
As above, can also generate high spikes if RF noise that can effect any electronics in the car.
In most electronic systems maximum power transfer from one device to another required impedance matching, NGK plugs have a 5k resistor inside,
magnicor leads have a spiral core with resistance of a couple of hundred ohms per foot. Add this together and you get about 8k with is the secondary
resistance of the coil. This is not a coincidence.
OEM HT leads work fine, but often have very high resistance for better EMI, the down side is when they get old, the resistance gets too high.
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posted on 29/4/14 at 11:08 AM
quote:Originally posted by Smoking Frog
quote:
I've done that, having found TDC you always get a 'Dead' area where the pulley will move without TDC moving. I've marked this
dead area to create my pulley mark
there are tolerances on every part of the engine - so true TDC will almost never be where the timing marks on the pulley say it is (even on a brand
new engine)
here's the locost / simple way to accurately find true TDC, you'll need this as a reference for setting your cam and ignition timing:
but remember that due to the tolerances on every part the engine may run better with cam and ignition timing a few degrees off what it says in the
books, even when the TDC mark is spot on - but the only way to find out is trial and error...
in fact you could just forget the mark and keep adjusting the timing a few degrees either way until it runs right by trial and error
my old fiesta (very similar to the x-flow) ran best about 10° - 12° on the marks, but I never bothered to find true TDC so I can't tell you how
far off the marks were and how much was due to the fact it was running on 98 octane LRP rather than than the 4 star it was designed for. - I just
tuned it by ear then used the strobe to find out were that was for the next time
quote:Originally posted by threadbare wallet
Whats wrong with copper core leads?
TVI!
Yes television and radio inteference was the bug-bear of copper HT leads I was learned to believe.Though in these days of universal almost bomb-proof
digital comms that sort of inteference is no longer an issue- No?
Yes television and radio inteference was the bug-bear of copper HT leads I was learned to believe.Though in these days of universal almost bomb-proof
digital comms that sort of inteference is no longer an issue- No?
Digital electronics can suffer from EMI just as much as analogue, noise via power/ground cables can really upset processor based devices.
For example, a current loop communication system such as 4-20mA as used in process control in every power station is less susceptible then serial
RS232 or even RS485
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but remember that due to the tolerances on every part the engine may run better with cam and ignition timing a few degrees off what it says in the
books, even when the TDC mark is spot on - but the only way to find out is trial and error...
in fact you could just forget the mark and keep adjusting the timing a few degrees either way until it runs right by trial and error
my old fiesta (very similar to the x-flow) ran best about 10° - 12° on the marks, but I never bothered to find true TDC so I can't tell you how
far off the marks were and how much was due to the fact it was running on 98 octane LRP rather than than the 4 star it was designed for. - I just
tuned it by ear then used the strobe to find out were that was for the next time
[Edited on 29/4/2014 by mcerd1]
Agree with the above just to get it running at idle, but not a good idea to assume its all fine and OK to drive, tuning engine by guesswork normally
ends in tears.
Anyway, as you said you should be able to get it running by fiddling with the dizzy for best idle.
If no luck bin the ignition amp and go back to points if possible or buy a decent electronic system. Best solution all round would be megajolt.
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posted on 30/4/14 at 01:54 PM
quote:Originally posted by BaileyPerformance
Agree with the above just to get it running at idle, but not a good idea to assume its all fine and OK to drive, tuning engine by guesswork normally
ends in tears.
fair point, when i was tuning mine by ear it was on the assumption that it was pretty close to start with
mine was a 100% original car with everything working perfectly and exactly as it left the factory - it only had 25k on the clock when I got it at 21
years old (and I knew were it had been since new)
without modifying it all I could do was set the advance with the vac. advance disconnected and trust that the dizzy was working as it was intended -
then see how it went and adjust it a couple of degrees if needed (mainly to allow for the weird LRP fuel that you can't even get now)
posted on 29/4/14 at 11:54 AM
