Griff 500 bouncing rev counter
Discussion
robsant said:
Ahh thanks
The car has magnecor kv85 competition leads.
Why do they make the Rev counter bounce ?
They are about the worse leads you can fit to a road engine, as the lead resistance is very low, that leads to big voltage spikes in the coil primary as it switches. This causes the glitching of the rev counter. You can try more resistance in the spark path, like resistive plug shrouds or resistive plugs. The cheapest option however is to put a standard carbon cored king lead in from the coil to the distributor, which may be enough to calm things down. The car has magnecor kv85 competition leads.
Why do they make the Rev counter bounce ?
The power the spark delivers is irrelevant once the combustion process has started, so you only need enough power to start the burn reliably and no more, as the excess energy simply burns the plug tips out and spikes the coil. Any idea that fitting low resistance race leads to a road engine to produce more power is just wishful thinking im afraid- not that stops anyone out to make a fast buck of of these highly over priced leads selling them.
So much for "85KV" voltage rating on the red leads - the RV8 system peaks at no more than 40KV and thats what happens!
On plug leads in general, dont forget to check out plug lead sets for the Range Rover 3.9 classic, they should all fit apart from the king lead to the coil that I think is a different length on the TVR. You dont have to pay TVR tax.
On plug leads in general, dont forget to check out plug lead sets for the Range Rover 3.9 classic, they should all fit apart from the king lead to the coil that I think is a different length on the TVR. You dont have to pay TVR tax.
Bit more info and possibly useful linky here...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
blitzracing said:
They are about the worse leads you can fit to a road engine, as the lead resistance is very low, that leads to big voltage spikes in the coil primary as it switches. This causes the glitching of the rev counter. You can try more resistance in the spark path, like resistive plug shrouds or resistive plugs. The cheapest option however is to put a standard carbon cored king lead in from the coil to the distributor, which may be enough to calm things down.
These spurious voltage spikes for each spark you mention must also play havoc with the ECU's Spark Interrupt code especially when it's trying to calculate the Spark Ignition period, given that the White/Black feed to the Rev counter also goes to pin 39 of the ECU. There should be a series 6.8K Ohm dropper in the circuit but is that sufficient?Gassing Station | Griffith | Top of Page | What's New | My Stuff