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Spark plugs for 400HP 308

Started by _LHSL308_ , Sep 07 2013 05:33 PM

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11 replies to this topic

#1 _LHSL308_

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Posted 07 September 2013 - 05:33 PM

I am currently running a 400FWHP 308 in my LH and I was just wondering what spark plugs some members here used for their 308's?

Mine was fully rebuilt 1000km's ago and I am already having problems with the plugs fouling up. Had to change 2 plugs about 200km's ago just to get the car started and they had some serious carbon on them.

Currently using NGK BP7FS plugs and haven't had 12 volts out of the coil changed yet which will no doubt help with keeping the plugs cleaner. I guess the fact that I have been taking it easy for the first 1000km's as I was running the engine in hasn't helped either.

Engine seems to run on 7 cylinders when started up cold but once it been running for about 10 min then it starts to blow the cobwebs out and runs how it should.

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#2 rexy

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Posted 07 September 2013 - 06:02 PM

Funny, I just went a heat range hotter in my early headed 383. I changed from NGK BP6F to BP5F.
Combo is COME bottom end, 10.2:1 comp, L34 style early heads(VL), torker single plane intake, Bosch HEI, pacemaker 1.75 inch primary tri Ys, split pattern solid crane cam 240/244 @ 50 thou. 750DP Holley.
The torker has pretty crappy fuel distribution in general street use looking at the plugs. I will probably try the spare performer on it soon.

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#3 _LHSL308_

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Posted 07 September 2013 - 06:12 PM

It has been suggested I may need to try a hotter plug. I have seen and read a bit about these iridium plugs being pretty good however their about 3 times the price but probably last a lot longer too.

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#4 Struggler

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Posted 07 September 2013 - 06:13 PM

For a streeter or something that doesn't get flogged mercilessly the 7's are too cold.

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#5 Ice

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Posted 07 September 2013 - 07:02 PM

My torana was doing the same wayne brand new engine plugs fowling up
just got the hotter plugs
all good now

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#6 _SS Hatchback_

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Posted 07 September 2013 - 07:14 PM

not sure how much fwhp but im running 312 rwhp out of my early headed red 308 and im using NGK BP6FS, no fouling and seem to work ok with my combo

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#7 _LHSL308_

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Posted 07 September 2013 - 07:55 PM

Have you guys got the 12 volt coil conversion done? I am supposed to have all the plugs changed on Monday so I might try the BP6FS plugs.

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#8 _SS Hatchback_

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Posted 07 September 2013 - 08:17 PM

yep mines all converted to 12v

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#9 _LHSL308_

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Posted 07 September 2013 - 08:53 PM

yep mines all converted to 12v

I'll get that done at the end of the month. In the mean time i'll get some BP6FS plugs and try those.

Thanks guys.

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#10 _LHSL308_

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Posted 15 September 2013 - 10:44 AM

Got the NGK BP6FS plugs installed yesterday and I must say they are quite an improvement. The old plugs were carboned up quite badly which made the engine run shithouse especially when it was cold. I know the new plugs would be expected to fire the engine pretty well being new, but I can honestly say the engine has never ran better even when I got the engine back from its rebuild some 1100km's ago. The engine just loves these hotter plugs and I do to.

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#11 _SLEDGE_

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Posted 15 September 2013 - 01:44 PM

not sure how much fwhp but im running 312 rwhp out of my early headed red 308 and im using NGK BP6FS, no fouling and seem to work ok with my combo

420 fwhp. Torana/similar drivetrains should amount to about a 26% power 'loss' at the rear wheels

Got the NGK BP6FS plugs installed yesterday and I must say they are quite an improvement. The old plugs were carboned up quite badly which made the engine run shithouse especially when it was cold. I know the new plugs would be expected to fire the engine pretty well being new, but I can honestly say the engine has never ran better even when I got the engine back from its rebuild some 1100km's ago. The engine just loves these hotter plugs and I do to.

Good result! I didn't know plug heat ranges had such a big effect. I might try a set of hotter plugs too

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#12 _LHSL308_

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Posted 15 September 2013 - 02:00 PM

420 fwhp. Torana/similar drivetrains should amount to about a 26% power 'loss' at the rear wheels

Good result! I didn't know plug heat ranges had such a big effect. I might try a set of hotter plugs too

Jack at mid to top end range I would say there is a little improvement from where it was. At the low to mid range is where I have found the engine to be much more responsive. I am hoping the fuel economy will be a little better as well, was only getting about 150kms out of a full tank before.