Thread: Recommended spark plugs?

Originally Posted by JDNSW

No. This is an early 7:1 head - what you are looking for is a raised, square, boss exactly where you have marked, where the number you show is. The 8 or 7 on the boss is stamped on not cast. The cast on numbers relate to the foundry that cast the head and the batch number.

John

Thanks John. I needed to get some new plugs and now know the compression.

I've been trying to solve a running on problem.
Checked timing and played with fuel mixture. Dizzy and carbie have been professionally reconditioned so now thinking of putting in new or possibly cooler plugs.

Originally Posted by LandyDude

Thanks John. I needed to get some new plugs and now know the compression.

I've been trying to solve a running on problem.
Checked timing and played with fuel mixture. Dizzy and carbie have been professionally reconditioned so now thinking of putting in new or possibly cooler plugs.

Running on is a problem with these engines - some of the things that encourage it are need for a decoke, plugs (as you say), and probably easiest to fix, either excessive idling speed (should be around 500rpm, much lower than contemporary engines), or incorrect (retarded) ignition timing. The other thing is to allow it to idle for thirty seconds before switching off.

John