Bosch Platinum..What gap size?

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Jun 10, 2013 | 10:07 AM

raiderz

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From: Hamilton Ontario

Bosch Platinum..What gap size?

Hello:

Early 1986 coupe..L98 cast iron heads...stock motor..stock ignition system

I purchased a set of Bosch Platinum 4208 plugs and was reading on Rock Auto that the recommended gap size is 0.45.

I have always gapped my plugs to 0.35" for the engine...as it states in the manual.

What should be the gap size for these plugs on my engine??

Thanks

Last edited by raiderz; Jun 10, 2013 at 12:00 PM.

Jun 10, 2013 | 11:32 AM

JrRifleCoach

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From: Freedom is never more than one generation away from extinction.

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Stick with what you know is right.

I gap mine at 45 but Im also running an MSD box.

Jun 10, 2013 | 03:54 PM

LongBeachC4

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From: Long Beach Ca,

Just did my AC1 plugs at .45, seems to work good. I do run a Pertronix coil and module. The .35 gap was fouling at about 8000 miles, I don't think they were burning the charge completely .

Jun 10, 2013 | 09:41 PM

raiderz

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From: Hamilton Ontario

Quote:

Originally Posted by LongBeachC4

Just did my AC1 plugs at .45, seems to work good. I do run a Pertronix coil and module. The .35 gap was fouling at about 8000 miles, I don't think they were burning the charge completely .

So if im reading this right...the larger the gap...the hotter the plug? will burn off oil and carbon better?

Im still confused as to what to gap these Bosch Platinum plugs at?...My old plugs...i have one old ac delco plug that has minor oil/carbon build up on it..doesnt look serious..the rest look normal at whiteish/light browning.
These are gapped at 0.35

i would appreciate everyones thoughts...maybe i'll split the difference and gap em 0.40??

Jun 11, 2013 | 02:21 AM

Cliff Harris

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From: Anaheim CA

The gap isn't really critical unless you go to very high RPM, in which case you might get a miss with a large gap. The restrictions in your intake manifold will keep that from happening.

Jun 11, 2013 | 03:18 AM

jez3941

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i just bought Bosch Platinum platinum plugs for my 86 with iron heads and the computer at auto zone said to gap at .045 for iron and .035 for aluminum heads