Davis Unified Ignition

I’ve been slowly renovating my 89 Range Rover, I’ve done a new 3" exhaust, new bushes, rebuilt the LPG converter and mixer, but I’ve still got a little firing problem on the gas side.

It runs under low load OK but gets a misfire happening at full noise pedal, but only on gas, goes like a stabbed rat on 98 octane dinosaur juice.

The leads, plugs and dizzy cap are less than 12 months old, the ignition module is brand new, buuut, the coil is ~15ish years old.

The only gas mechanic withing cooee (actually there’s 2 but I want to stab the other vigorously with a pig sticker) says it sounds like ignition related as gas needs more spark to fire.

I’m thinking, rather than just replacing the coil, it might be worth replacing the old vacuum advance dizzy and the oil filled coil with a Davis Unified Ignition dizzy with integral 50KV coil and mechanical advance.

Anyone here got the knowledge/experience to offer any constructive advice?

in another life, I was a ( LPG) Mechanic ( it would be late 90s since been on the tools, back when it was 9c a litre ) … and Spark was always a " issue " on LPG, back then MSD did some really good bolt on multi spark Ignition coils, as it would receive the signal from the distributor and fire the plugs several times in succession… worked great … also, a poor mans way to improve cold starting and LPG running was to close the spark gaps a TINY bit ( as in a though or 2) usually helps a tired or weak spark, but I didn’t like doing that as it masks a problem, not fixes it … anyhoo, definitely could be spark, LPG is picky on that…

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Plug gap is set at .8mm now.
What I was hoping to do was up the voltage so I could open yhe gap and get a longer spark.
I’ll look into the msd coil pack :beers:

Isn’t the timing curve also different for lpg to petrol, we could never get them to run sweet on both, had to pick a fuel and tune to it. Might need more advance at high load/rpm

I’ve decided to bite the bullet and stop dabbling in the dark.
I’m way out of town so if I stuff something up it’s a long walk.

I rang a Land Rover performance engine builder in Sydney and they suggested I get a sniffer up it and get someone who knows to tweak things with the exhaust anyliser input.

They also gave me the great news that despite the rebuild of the converter, it might be rooted and need replacement