6 replies to this topic

[bantamben]

I have a mini with a 1275 i just built with 10.5 compression i have no pinging at all and im running around 10 degrees at 1000rpm around 30 total advance. Im having problems with dieseling when i shut it off the engine isnt overheating. And it only happens when its good and warm from being on the freeway. Im tthinking maybe the spark plug is too hot and igniting the little gas at shutoff coming from the hif44 su. I am currently running an ngk bp6es thinking of trying a bp7es wich is the next colder plug. Anyone have any experience with this thanks.

[Paul Wiginton]

I use B7 on the road with 12.5:1. They are pretty good but you could also try B8 but they could make it harder to start when cold.

Paul

[jaydee]

Mine is 10,50:1 (but its a 998) and i run bp6, bp8 seems a bit excessive on a road modded 1275. I relate ur run on problem to a excessive advance for the fuel you are running, try bp premium or v power and see if that cures the problem.

[bantamben]

i run 92 octane here in the us like i said no pinging i even tried running an additive octane booster didnt make a difference.. Im gonna try a ngk br7es see how it works

[jaydee]

92 octane fuel..that maybe good for a low compression 998, but i would never use it on a 10,5:1 compression 1275. You need 97/98 octanes..
You got no pinking because ignition is basically in good working order, but run-on is a different thing and changing spark plug wont affect that.

[998dave]

Isn't an MG Metro 10.5:1? You could check what they run, though I think it's BP6es

[Cooperman]

I use BP6ES in my Cooper 'S' rally car which has 11.2:1 CR. They are fine. I have used BP7ES and they are also fine, although once, when it was really cold and the engine did not warm through they oiled up a bit and took a while to clear after I put a piece of cardboard over the LH side of the grill (was on a rally at the time).