Outer Limits 4x4 Board

Which plugs and setting should I use for my new RR on LPG. 1986, 3.9 litre.

It originally had Champion n9y, but had a set of Champion n12y in the back. I've just fitted these. I usually use NGK.

What should I use for LPG?

NGK BP6RES from memory, I believe they are 1 colder than standards
and they need to be gapped to 0.7mm IIRC

Someone correct me if I am wrong here pls !

Tom

RaginRover wrote:NGK BP6RES from memory, I believe they are 1 colder than standards
and they need to be gapped to 0.7mm IIRC

Someone correct me if I am wrong here pls !

Tom

No correction needed Tom
The NGK website lists the BP5RES for a standard 3.9.
Then for gas, go 1 colder, ie BP6RES, and then reduce the gap by 0.1mm to 0.7mm.

So although the Champions are brand new, gapped to .8mm I should chuck them and go the NGK's?

Will there be that much difference. It doesn't seem to go much better than my old 3.5 auto (petrol only) at the moment.

Well according to Champion web site the standard plugs for a 3.9 Rangie are Champion Traditional spark plug 322 RN11YC4

Now it looks like you have gone for n12y which is one stage hotter. If you had gone for the n10y if you wanted to be precise.

It just means the LPG will wear the plug out sooner, like maybe 5000Km, check you timing advance it up for LPG start at 6 degrees and see how it goes. Advance it till it starts to ping on fuel then retard it so it stops pinging

Tom

ytt105 wrote:So although the Champions are brand new, gapped to .8mm I should chuck them and go the NGK's?

Had a dud set of Champion plugs for my Ford V8 about 20 years ago.
I swore I would never buy another Champion plug (not even for the lawn mower), and never have since.

DITTO, Champion plugs are filed in the big blue COLLEX filing cabinet, only used NGK in RR V8's for last 12 years, no probs.

JC