1 reply to this topic

[colinu]

Hi,

 

What spark plug gap size should be used when running a MegaJolt ignition system? To date I've been using NKG BPR6ES set to default gap (0.036"). Runs fine, but I'm just curious if it is 'optimal'.

 

   Regards,

   Colin.

 

FYI, my engine is 1380cc, stage 4-ish head (35.6mm Inlets, 31mm exhausts and an lot of flow/porting), AC Dodds AC-RS+ cam, HIF44, and MegaJolt V3 running a MAP sensor.

 

[tiger99]

You should probably ask the Megajolt manufacturer, but 36 thou seems reasonable to me. The City E used to run 35 thou with a simple updated coil and standard points so it is not excessive. But the recommended grade of Bosch plugs were not up to it, and had a very short life, so I used NGKs like yourself. Can't remember which grade but that is not relevant as the engines are different.

You could try increasing to 40 thou, and if there is no deterioration, maybe a little bit more. If it runs reliably at 36, no point in going lower. A short spark is not as good as a long one, provided that the long spark reliably happens when required.