enginehistory.org

[rkammlott]

thanks Dave for that info. the threads are 14mm on the head side and bs on the plug ends. The merlin plugs may not be correct for this engine but should fit the harness . thats why i was looking for a set. then I saw the price tag!! Im going to do the auto conversion spark plug unless some thing turns up. its a ground runner and never going in the air under my ownership.

[dirwin]

The plugs used varied over time from early to later engine. If you can advise which engine you are working on I will try and identify which plugs.

However, I am sure that there are several 14mm plugs that will work fine for a ground runner.

For RR Merlin II/III, they use:
KLG RV 14/4
Lodge RA 14/4
- Gap 0.012" - 0.015"

For later Mk22 - 24:
Lodge RS type 5/7
KLG type RC5/4
AC type RZ5
- Gap 0.020" + 0.002"

For my engines, I have fitted Lodge RS5/7.

Availability of plugs can be a problem; RS5/5 used in DeHavilland Gypsy engines will suffice for ground running at low boost.

Regards,

DAI

[rkammlott]

anything would be helpful!! the engine is a armstrong sddeley cheetah x radial engine. I need a full set of plugs. and some other impossible parts to locate. Carb and manifold, 1 cylinder (complete) and a few rocker covers. any leads or thoughts would be great.