Thread: Recommended spark plugs?

The NGK web site says B6ES for 7:1 compression, and BPR5EIX for 8:1 compression, where:

B = 14mm
P = projecting insulator
R = resistor i.e. not inductive resistor
5/6 is the heat rating
E = 19mm thread
IX = induction, S = standard

The plugs in my engine are BPR6ES, which I would take to be identical to B6ES except for the projecting insulator.

The BP5ES you've had recommended are lower heat than NGK recommend, but it may not make a significant difference - someone else in the forum may be able to add to that.

The Bosch and Champion web sites are not helpful, but the NGK site says the equivalent of Champion N9Y is BP6ES and the equivalent of Bosch WR8DC is BPR5ES, which pretty well supports the original NGK recommendations but still doesn't give you an unequivocal recommendation.

Peter

Thanks for that. So many websites, so much 'different' info. I started to run a spreadsheet listing all the equivalents I could find for all the parts - and quickly found that some cross references were at odds with others.

*sigh*

It ain't easy

First thing you need to do is determine whether you have 8:1 or 7:1 compression.

On top of the head, between the rocker cover and the carburetter, there should be a square boss. If this has an 8 on it, you have 8:1, otherwise 7:1. The number may be very faint. If no number, or if the boss is not there (early 7:1 heads) you have 7:1, unless the head has been ground and not marked!

For 7:1 NGK B6ES and 8:1 BP5ES according to my information.

The original recommendation in my owners handbook was Lodge CLN-H Long reach, or in the Series 3 owners manual Champion N8 (7:1) or N12Y (8:1)

John

thankyou John. I think it was one of your threads where I found the B6ES info.

I'll go look for that boss and, if found, scrub it (it's kinda murky under the bonnet still - well overdue for a clean - but I have only had it a few weeks)

Well - that was messy

There is a hole in my exhaust manifold. The previous owner had filled it with gunk and placed a folded bit of tin over it to stop the exhaust heating the hell out of the carby...

So - removed tin - sprayed a bit of WD40 onto the lug. Scrubbed vigorously with a wire brush and I can see an 8 sitting there - quite distinctly.

So I have an 8:1 ratio head.

I have a set of BP5ES plugs so they will get used - and the brand new set of B6ES plugs that arrived today can go in the drawer...

Having now discovered the extent of the manifold damage, may I ask - how hard is it to get one and roughly what would I expect to pay?

Thanks

John

Originally Posted by drifter

Well - that was messy
............

Having now discovered the extent of the manifold damage, may I ask - how hard is it to get one and roughly what would I expect to pay?

Thanks

John

I replaced mine about five years ago (cracked). Readily available, mine came from Four Wheel Drives in Melbourne for $115. Not very difficult to do, except you can expect some of the studs to break or be missing. You will need new gaskets for the head and the intake manifold, and plan on replacing at least some of the studs, nuts and washers. The nuts on the exhaust pipe flange should be brass.

John

Thanks John

I have a gasket set (valve regrind set - CD770 - ex Melbourne) that I am saving until I get all the other bits I am needing and then I'll do it all in one big job. I see there is an exhaust gasket in there.

I'm a bit worried about the studs I know are going to break (ahead of time) so I'll be seeking some of those, too, as time goes by.

Originally Posted by JDNSW

First thing you need to do is determine whether you have 8:1 or 7:1 compression.

On top of the head, between the rocker cover and the carburetter, there should be a square boss. If this has an 8 on it, you have 8:1, otherwise 7:1. The number may be very faint. If no number, or if the boss is not there (early 7:1 heads) you have 7:1, unless the head has been ground and not marked!

G'day John

Is this what you mean as below in the picture? Mine has "23 8R", I guess the '8' makes it a 8:1 if I understand correctly?