[Mg-mmm] MG PA spark plugs

[Hiro Nishio]

Lawrie, Terry, Pete, and all,

First of all, there are usually two reach lengths available, longer one is
3/4"(19mm) and shorter 
one is 1/2"(12.7mm). In case of NGK, "BP" means longer one, and "B" means
shorter one.
3/8" (9.5mm) is hardly used in my case.
And there are two kind of tips, extended one (ES) and normal (HS).
Hence BP6ES has 3/4"(19mm) reach and extended nose. B6HS has 1/2"(12.7mm)
reach and normal tip. 

Theoretically I think the long reach + extended nose plug would ignite well
inside the combustion chamber, 
but after trying many kinds of plugs including iridium to M/J/P/F/K/L/Ns,
the actual result was vary, 
some car was good with BP6ES, but some was good with B6HS.

Recently I rebuilt an F Magna engine (it had 14mm thread instead of original
18mm - someone in the past 
modified) and I thought BP+ES should be good by exactly the same thought as
Lawrie.
Then fitted BP6ES first, not satisfied. Then changed to BP6HS, which I
usually use for any normal MMMs, 
better but not perfect, then finally B6HS, very good. No misfire occurred at
all finally.

Lawrie, spark plugs are cheap, so try many and find the best one - it is one
of the fun given to us 
to play with old MGs.

But do not use iridium plugs! That's expensive but no good for MMMs, unless
rather lean mixture setting.

Good luck,
Hiro

-----Original Message-----
From: mg-mmm-bounces at autox.team.net [mailto:mg-mmm-bounces at autox.team.net]
On Behalf Of Pete Thelander
Sent: Wednesday, October 28, 2009 9:11 AM
To: TATERRY at aol.com; lawrie at britcars.com; mg-mmm at autox.team.net
Subject: Re: [Mg-mmm] MG PA spark plugs

Lawrie, Terry et al,

I have been using the NGK BP6HS for the past ten years in the NE.  The 1/2"
reach plugs are a bit short, but that is why I run the extended tips.  So
far as Terry using 5s and my using 6 or 7s,  The compression ratio is up to
the original spec at 9.8:1.  I don't think Terry is near that high, so the
5s might be more appropriate for his car.

Pete 
pthelander at earthlink.net



> [Original Message]
> From: <TATERRY at aol.com>
> To: <lawrie at britcars.com>; <mg-mmm at autox.team.net>
> Date: 10/27/2009 4:23:00 PM
> Subject: Re: [Mg-mmm] MG PA spark plugs
>
> Lawrie, I am using NGK BP5HS plugs in the NA....seem to work well but not 
> so much time or mileage yet....these are 1/2" reach with an extended 
> nose....recommended by Bob Bazzica for use in all my cars, TA, TF, Arnolt
and NA.....
> What are others using?
> Terry
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