Spark Plugs

CNHSS1 · #1 30-03-2007, 10:08

the second set (exh side) were to burnt off any unburnt fuel for use when the vehicles were fitted with catalysers, it was for emissions rather than performance (unlike the Alfa twin spark engines). when i had a car with the 8 plug ET setup, i went colder on both (from 5s and 6s to 6s and 7s) when i turned the boost up.

30psi · #2 30-03-2007, 10:12

I'd say go for 7's on the exhaust. Being near the exhaust valve and prone to more heat than standard, if they're coked up this will glow red leading to pre-igntion.

Conkers · #3 01-04-2007, 07:59

I changed them to 7's all round and she runs fine... ish!.. actually the electrodes were completely missing on some of the plugs, possibly due to fuel surge whilst doing donuts and the engine going lean.... did a compression test and #4 is down a tad... so as we had planned on tuning anyway, I'll pull the head, port it and sort it... but thanks for the advice... 7's all round made it run fine... top tip.

Mike.