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What heat range plugs for straight gas?

Started by _73LJWhiteSL_ , Jan 18 2006 04:37 PM

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8 replies to this topic

#1 _73LJWhiteSL_

Guests

Posted 18 January 2006 - 04:37 PM

gday all,

What heat range plugs should i run in the LJ on straight gas now? Its a stock 173 with Commodore electronic dizzy.

Steve

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#2 _CHOPPER_

Guests

Posted 18 January 2006 - 06:04 PM

Check how the current plugs are burning after 5000 KM. If it starts playing up, use 1 range colder and see if that helps. I ran 2 stages colder on my straight gas 173.

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#3 _devilsadvocate_

Guests

Posted 22 January 2006 - 09:33 PM

Its recommended that just due to the burn speed characteristics of lpg to go at least one stage colder. A plug that is too hot could be the cause of slight preignition that wont even be noticeable by the distinctive sound one gets if the timing is too advanced, but can be just as damaging to the tops of the pistons.
A plug pulled out of a gas engine after 5000km should/will look brand new, but wont give you any idea whether it was preigniting the mix. Off course if it is too cold, they will be sooty deposits on it.

Edited by devilsadvocate, 22 January 2006 - 09:36 PM.

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#4 _73LJWhiteSL_

Guests

Posted 23 January 2006 - 12:41 PM

Thanks for the suggestions people.

I am running 7s, so one range colder. Thats what the gas people put in.

Steve

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#5 _devilsadvocate_

Guests

Posted 23 January 2006 - 10:02 PM

Thanks for the suggestions people.

I am running 7s, so one range colder. Thats what the gas people put in.

Steve

What brand of plug is that?

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#6 _73LJWhiteSL_

Guests

Posted 24 January 2006 - 12:12 PM

NGK

I think they are like BP7FS i think.

Steve

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#7 _devilsadvocate_

Guests

Posted 24 January 2006 - 12:47 PM

Okay, 2 ranges less colder than standard petrol plug, should be fine - just check for any fouling over you running in/trial period of your system. Let us know how it goes, was thinking of doing perhaps going to those on my next set, but heh, that could be another 100 000km b4 they wear out.

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#8 _73LJWhiteSL_

Guests

Posted 24 January 2006 - 02:27 PM

Well I have been running 6s pretty much ever since I been running PULP and haven't had any problems with them.

BTW my flat spot problem was in relation to a jet being to small. That has since been fixed. It still flat spots slightly but its not as bad as it was.

Steve