Spark Plug Gap w Pertronix

[vande17941]

hi. Could somebody with experience please tell me a good starting gap for a 7 or 8 Bosch heat range plug after upgrading to the Pertronix electronic ignition with the Pertronix hotter coil In a 230sl.  Thanks

[Benz Dr.]

Use NGK  BP5ES instead; gapped to about .035''

[vande17941]

Will do. That's a bit hotter plug....I drive that Pagoda hard....mountain roads, high speed cruise etc. ...it is not a trailer queen and it is definitely not even close to babied...I'm a past shifter kart racer. ...is that still okay with an NGK "5" plug?

[Benz Dr.]

I think so. The 5 crosses over to about a 9 in Bosch but they are not making any more non resistor plugs so that's why I changed to NGK. The fuels are different today than 40 years ago and most spark plug reconmendations are out of date. Every book I've ever looked at all called for a 7 in Bosch but they're too cold for almost every application I've worked on.

[vande17941]

great. Thanks. I'll give it a try and then read the plugs and see how I do.

[mdsalemi]

Dan, I've been running NGK BP6ES for a long time. Based upon your note here, and since it's about time to change/look at the plugs anyway, I just ordered a set of BP5ES.
This -5 is a hotter plug than than the -6, yes?
What should I expect if anything, in operating? What should I be looking for to see if this is better, worse or about the same?
I too have a Pertronix...and the -5 is gapped to about .035.

[Benz Dr.]

5 is a bit hotter than a 6.

 Look for a uniform tan colour on the insulator around the center electrode. The outer shell is often black but that's not a problem. If the insulator remains bone white after a short amount of driving you are actually too lean and it's not a function of having a spark plug that's too hot.

 You should see a nice warm up cycle without any loading up, hesitation, or real changes in the exhaust note. Engine should pull hard warm or cold. 

[mdsalemi]

We'll give it a go!

[vande17941]

NGK lists BP5ES under 2 different stock numbers.  I suspect one has a removable terminal end, which is what I need. Anyone know which model we want, 6511 or 7832 with the removable terminal?

[Shvegel]

6511 is the base copper core plug that comes with the 4mm threaded stud without the threaded nut and the 7832 has the threaded stud with the removable nut.  The real difference for you is the 7832 features better plating to help keep it from seizing in the cylinder head.

[vande17941]

Great info...thanks everyone.