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Changing twin spark Z24 to single spark?


hoare85
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Why mess with it? It's not like it's a problematic setup.

 

yeah...why do you want to mess with it? It has twin spark plugs for a reason...and, if you ask me, it works damn well.

They have twin sparks because of ignition. The engines back in those days had some problems burning all the fuel because of ignition. To fix that, they put in dual spark plugs to double the spark. I don't see any advantage to switching to a single spark plug head.

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yeah...why do you want to mess with it? It has twin spark plugs for a reason...and, if you ask me, it works damn well.

They have twin sparks because of ignition. The engines back in those days had some problems burning all the fuel because of ignition. To fix that, they put in dual spark plugs to double the spark. I don't see any advantage to switching to a single spark plug head.

 

Um. No, they are twin spark for emissions. Z24s have an emissions head. My '76 L20 TOTALLY has a problem with not enough spark, yep because it's old. So do all the old single spark plug engines that purr like kittens. :rolleyes:

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Yeah i know it would have been to do with emissions, only reason i ask is that save replacing twice the amount of plugs and leads, my dads 89 navara was a single spark Z24 an used the exact same amount of fuel as mine and drove just as well maybe a little better as it had half the K's on it but it would hav also been slighty lighter aswell..

 

My plan is to give it a try keep records of fuel consumption and how it runs with single and twin plugs once i have fitted and ran in the engine that i've rebuilt.. I'll let ya's know how it goes and what differences i see when i do it :)

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Um. No, they are twin spark for emissions. Z24s have an emissions head. My '76 L20 TOTALLY has a problem with not enough spark, yep because it's old. So do all the old single spark plug engines that purr like kittens. :rolleyes:

 

I mean, yeah. If you don't burn the fuel, then you just dump it out the exhaust. That sounds like emissions to me.

What's up with the double sarcasm? So your L20 doesn't have a problem with spark, but then your rolleyes emoticon suggests that it doesn't run well. I'm confused. Maybe it's because I'm young.

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Awesomesauce. Theoretically it would seem that you'd only need the single plug distributor and (I think) M14x1.25 bolts for the unused holes.

 

 

I seem to vaugely remember one of my co-workers trying this and I think he had running issues without the extra sparks.

Edited by MY1PATH
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  • 8 years later...

Thread revival here! But if anyone is thinking of changing from twin to single spark on a Z24, you will also need the oil pump drive from a single spark engine as the distributors are different lengths. 
I set mine up like that years ago, simply left the 2nd row of plugs in the LHS side of the head and ran leads to the RH side.
It ran perfectly and it gave me no trouble for the 11 years I owned it. It did like to run on if the timing wasn't dead right, but I got that nailed pretty quick with a new electronic ignition. 

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My 1980 200SX was a federal model, so had the Z20 single spark head. With that car, only the federal emissions and 1980 model year was that way. California and 81 and later had the NAPS Z dual ignition. 

Car ran fine until I crushed the oil pan and welded #2 rod to the crank. Replaced with a low milage import engine that oddly enough had a carburetor and breaker points and 8 spark plugs. I had to swap the oil pump/distributor drive shaft to install the 4 plug distributor from the original engine and I think I just used the 4 intake side plugs. Car ran fine and passed emissions tests ok. Time passed and I think that engine moved into an 81 510 wagon when I finished building a Frankenstein engine for that car. Used a Z24 block from an 85 720 pickup, Z22 head from an 83 200SX, flywheel and clutch from my 75 280Z. That engine I ran all 8 plugs, I had swapped the electrical system from an 83 SX I had bought as a parts car. I had messed up when I ordered the Pistons, I was after some flat tops, but wound up with standard ones. Actually was glad later, since I had to run premium during the warm months to keep detonation under control. I recall the distributors had different connectors for the wiring between the single and dual ignition. 

Upshot was, car ran fine on a single set of plugs, but cleaner when running both. The way the system worked, the exhaust bank fired just after the intake bank which gave a longer burn and I think a little smoother running engine that was a bit less sensitive to altitude and cold temps. I see no advantage of going from the dual spark to a single with the Z series engines. My L series engines had a different shape to the combustion chamber than my Z series, which is why I think they did the dual spark with the Z. 

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