Spark Plugs for Twin Plug

[chris_seven]

I am trying to decide which plugs to use for a Twin Plug 3.0 litre with 10.5:1 pistons and GE60 cams.

I think that the plugs in standard engines changed from a Non-projected to projected type in Mid 1978 and I am a bit concerend about clearance.

I am thinking of NGK B8EVG or B9EVG ofr the 14mm plug and using a D8 or D9EVX for the second plug.

I am sure that there is plenty of experience around and there may be a better choice.

The car will be used on endurance rallies in East Africa.

[Henry Schmidt]

NGK BKR 6 EKUB
Bosch FGR 6 KQE

Adjust heat range (5,6,7,8) to suit intake and altitude

[chris_seven]

Henry,

Thank you

[lindy 911]

I have the same motor and run the NGKs that Henry lists with no issues.

Lindy

[Shoepop]

Originally Posted by Henry Schmidt

NGK BKR 6 EKUB
Bosch FGR 6 KQE

Adjust heat range (5,6,7,8) to suit intake and altitude

Henry, could you please explain why one would have to adjust heat range for altitude? I'm going to guess higher the richer so you need a hotter plug on cars with say carbs that don't compensate as well as a modern engine fuel management system?