# Why 8 spark plugs..??



## robertbrenner1 (Oct 26, 2009)

Thanks for stopping by,
I just bought a 84 720 truck, 4x4. It has a 4cyl. engine with 8 spark plugs..!!Please tell me all you know about ...why??
Thanks, Robert


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## pulsar86 (Aug 13, 2009)

My Dad had a 1985 Nissan Bluebird with th CA20 2 litre engine with the twin plugs. The primary plug is on the intake side and the exhaust side comes in at certain revs which someone else might know more about. I think the reason for the twin plugs was for cleaner emissions more than power.


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## SPEEDO (Jun 9, 2003)

^ correct, it was for better emissions


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## tin-bsr (Aug 9, 2010)

My car is Laurel with engine type CA18, 1809cm3 and 8 spark plugs, only 4 cylinders.
This is nice surprised!!!


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## BeyondBiscuits2 (Jan 18, 2006)

It is for completely burning all the fuel in the cylinders. The '80s were difficult times for automotive advancement it seems. But, there can be some good from a twin-spark head for us "hot rodders". If you wire the two coils together (sharing positive and ground wires), you can fire both plugs at once. I mated a CA20E twin-spark cylinder head onto my CA18ET engine in my 1986 Bluebird 1.8ZXT with positive results. You also have to swap distributors and coils.


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## smj999smj (Jan 1, 2006)

These days they accomplish this with coil on plugs and waste spark ignition systems, where the coil fires spark on the exhaust stroke as well as the intake stroke.


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## vtowntommy (Mar 4, 2007)

so would wiring the 2 coils together to the intake work on a stock z24 ? or would it overheat and cause problems, its so gutless always thought the 2nd coil was useless for exhaust


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## smj999smj (Jan 1, 2006)

I wouldn't wire the coils together. You could try using performance coils (ie Mallory Ignition) but I can't say how much differance it will make. Advancing the ignition timing about 3 degrees over stock specs tends to "wake up" most Nissan engines, but make sure there's no "pinging."


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