Spark Plug type

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Spark Plug type

Postby Mike Attew » Fri Jun 29, 2018 7:11 pm

Just wondering if there is a preference or best type of Spark Plug to use, the manual says AC 42 XLS so is it best to stick with these or does it really matter?
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Re: Spark Plug type

Postby Bob perry » Fri Jun 29, 2018 11:18 pm

42XLS is the recommended type, but I had NGK's in for a while and they seemed just as god.

Recently though, I was offered some Accuspark 3 point plugs at Beaulieu Spring Jumble on a special offer, so I gave them a go. Excellent performance, and starting, so far so I've left them in.

One thing I have noticed though, or I may be paranoid, is that the engine appears to run a lot hotter, although the gauge doesn't rise too far off 1/4, so I assume all is well.
Not boiled yet anyway, and no coolant loss so fingers crossed!!
Changed stat and coolant as well, thanks Fred, to make sure, so I will keep an eye on it.

Might just go back to the ngk' s to satisfy curiousity.
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Re: Spark Plug type

Postby StefanM » Tue Jul 03, 2018 7:27 am

It is not a big surprise that the manual recommends AC spark plugs as they are GM/Vauxhall original fitment.
Any modern equivalent will work just as fine ofcourse. NGK sparkplugs is always a good choice.
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Re: Spark Plug type

Postby 1972nail » Tue Jul 03, 2018 8:16 am

As Stefan says, any good make will be OK for the OHV engine. Fred has a stash of AC plugs in the Club Spares stock I believe.

As far as OHC engines are concerned many have reported that AC plugs work noticeably better than other makes. I do believe I noticed a distinct difference between AC and NGK plugs on a mildly tuned OHC with the AC being more suitable, but the effect may have been down to a combination of other 'servicing tasks' that were undertaken at the same time - timing, points carbs etc. On the other hand, I didn't notice any difference between AC and Champion on the same engine.

I use Champion ones in my OHC engine, only because I inherited a couple of boxes many years ago and I still have a few left.

Again, Fred should have the OHC AC ones in stock.
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Re: Spark Plug type

Postby droopsnoot » Tue Jul 03, 2018 10:16 am

That's interesting - when I first got an OHC I was chatting to a local Vauxhall specialist (when there were such things) and he told me to steer clear of Champion plugs as "the OHC engine doesn't like them". Good to hear an alternate experience.

I've generally used NGK in mine, but have more recently started using AC ones as I dropped on a load. Partly because I'm a slave to originality, and partly because they don't have the little ferrule on the end that unscrews, and it's one less thing to come loose and cause a poor connection.
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