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Old 07 May 2015, 13:21   #111
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Yeh you have to be careful with the spark plugs.
for tohatsus with standard heads you can run BR8ES, the E is extended so it reaches further in. But with a shaved head for more compression you need to be running BR8 standard length or else you risk having problems.
Need to check the 70 still to see which ones will work best. I usually run the Iridium plugs. You can check for interference by putting the plugs in and slowly turning the engine over by hand, then check if the pistons have hit them.
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Old 07 May 2015, 15:12   #112
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Majority of the time I see the profs running a simple copper plug without internal resistors. You can have a larger gap and get a larger, hotter spark but if you don't have a coil that can handle it, it will fry.

In a different application, I ran a better coil, copper plugs and a greatly increased gap. Made enough of an improvement to note. Also improved my efficiency.

Just trying to help if you hadn't already gone down that route yet.
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Old 08 May 2015, 04:04   #113
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i've not looked into it much, sounds interesting though
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Old 11 May 2015, 08:01   #114
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Just remember, it only takes three components, Gas, Air & Spark and boom you got fire. Looks like you put a lot of work and time into two of them. I think the third is your next step. The bigger and hotter the spark the better and quicker the boom.
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Old 11 May 2015, 15:29   #115
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Not sure I completely agree with you there. A quicker spark is less than desirable unless you're trying to advance your timing, which you can do by adjusting a linkage anyway.
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Old 11 May 2015, 15:33   #116
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Not sure I completely agree with you there. A quicker spark is less than desirable unless you're trying to advance your timing, which you can do by adjusting a linkage anyway.

Not sure you understand or how you got timing out of that. Not quicker, but BIGGER
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Old 11 May 2015, 15:37   #117
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Not sure you understand or how you got timing out of that. Not quicker, but BIGGER
Sorry I misunderstood!
yeh I'll look into it for sure. I've got uprated - nakuru - coils (from a motorbike) and iridium plugs on it on the moment. So dyou reckon an increased plug gap would increase power?

Edit: looked into it, and apparently increased spark plug gap gives greater power except usually at WOT, when you may even want less gap to prevent misfire?
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Old 11 May 2015, 15:46   #118
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Sorry I misunderstood!
yeh I'll look into it for sure. I've got uprated - nakuru - coils (from a motorbike) and iridium plugs on it on the moment. So dyou reckon an increased plug gap would increase power?
It will to a certain extent. Haven't found anyone that has provided an equation or rules of application. More of try and test in gap steps starting at 1-5/1000 from where you are at. There are general guides that should get you started. Would guess diving into the performance motorbike world as a start? If you go too far, not sure what happens with your setup. Most likely misfires with your coils unable to produce an adequate voltage for the wider gap.

Getting a larger gap which is closer to the center of the gas/air mixture is what you want. This is why I was saying that I found the NGK plugs to be shorter than others when you compare them for the exact same application. In my testing, I found that a wider gapped NGK was equivalent to a normal gapped Champion because the Champion extended further into the chamber.
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Old 11 May 2015, 16:52   #119
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So dyou reckon an increased plug gap would increase power?
Its going to make about the same difference to the boats overall performance as emptying your bowels before climbing aboard.
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Old 12 May 2015, 02:30   #120
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Its going to make about the same difference to the boats overall performance as emptying your bowels before climbing aboard.
That's the conclusion I'd come to to be honest! haha
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