Peoples thoughts on the difference in heat range. NGK spec BP6ES for 1275, but I was considering going from BP6ES to the BP5ES for my 1330. I think my plugs are just a bit to dark for my liking most likely due to rich mixtures. But was going to try a hotter plug, do I then also need to worry about pre ignition in doing so? Or is there not a great deal in difference between the ranges?

Also, whats a suggested plug gap? Running Pertronix Ignitor electronic ignition module with Pertronix Flamethrower Coil.

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http://www.youtube.com/user/Hanras

I run BPR6ES in the 1360 with a Dellorto carb. Plugs look nice.
I ran BPR5EY in the 1412 stroker (now owned by gafmo). Its plugs looked nice too.
I run a Nissan Pulsar dizzy with GT40R coil, plug gaps .030". I used to run wider, but got occasional misfiring at low rpm during warmup in winter. I reset them when they get to .033" now.
I'd try .035" in yours, go smaller if there's any misfire.

I have seen range 5 plugs give more torque on GR's engine dyno than 6s did.
Re the resistor plugs, I find they are more resistant to fouling, if used with good leads like Bosch inductive core, or GR's similar ones.

BTW you can tell if plugs are too hot, the end of the electrode will start to blister.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hey Doc,

With Barney's new specs, what would you suggest. Had a fair bit of misfiring during warmup also.

Naturally, I've retained the pulsar dizzy, but want to make sure I've got a headstart on setup from the outset.

ER

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http://www.rylstoneclassic.com

Cheers Doc, Ive also fitted a brand new set of Top Gun ignition leads TG4010B.

http://www.ebay.com.au/itm/Mini-850-100 ... 417645e05f

Sound like a basic core type "Top Gun Standard 5mm, 7mm & 8mm Ignition Leads feature a stainless steel spiral wound core."

What are your thoughts on indexing the plugs? Which direction do you see best for the plug ground electrode to face? Towards the valves or towards the piston?

Also what is the physical difference between BPR6ES and BPR5EY? The S and the Y?

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http://www.youtube.com/user/Hanras

I would put BPR5ES or BPR5EY in it, and gap them to .030".

@ Hanra, an ES plug is extended nose, EY is a little more extended.
I think indexing plugs is overkill on a road A series motor, it makes more sense on a SB or BB Chevy etc where the chambers are much bigger and flame propagation can be a problem.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Just went hunting and going by this chart on the NGK website, the S is standard and the Y is for a V-groove type electrode. All lengths appear the same judging by NGK specs. I guess the next question is, what is the difference between Resistor plugs and non resistor plugs?

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http://www.youtube.com/user/Hanras

Yes, the Y is V grooved electrode, it is also ~1.5mm longer stickout than an S, I have both types here.

Purpose of the resistor is RF emission suppression, but it also forces the coil to give more V to make it spark.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

For future reference here is the length difference between a BP6ES on the right versus a BP5EY on the left. As the Doc pointed out, the length of the electrode/snout is a tad longer.

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http://www.youtube.com/user/Hanras

Happy to stand corrected but from my recollection of plugs and heat ranges, the longer the centre electrode the cooler the plug heat range.
the plug is cooled by the incoming charge, so the more it protrudes the more cooling it will recieve.

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It's easy once you know how.

Nope sorry, it doesn't work that way- the longer the insulator, the longer the heat path to the body is, = it runs hotter.
Shorter insulator = runs cooler but more likely to foul.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Dunno what was going on in my head then?
the main thing here for me is they are now a good tan colour.
had to get creative with the main needle. (superglue and hammer)
it had come loose in the little top disc and moved upward causing massive overfuelling, blowing thick black smoke rings.

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It's easy once you know how.

You mean in the SU yeah?

Anything in a carb fixed with a hammer sounds pretty dramatic!

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Yeah the SU.
I do have some small hammers Mick, I didnt have to get out the 3kg police hammer.
the repair is temporary until I get hold of a replacement main jet assy and damper spring

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It's easy once you know how.

Hi Doc,
have been having a bit of a misfire on warm up myself, Number 1 & 4 appear too lean, but 3 & 2 are ok.
valves are adjusted ok, any clues?
cheers

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It's easy once you know how.

Misfire when cold can be mixture too lean, too wide plug gaps, wrong heat range plugs (too cold), crook plug or coil leads, damp dizzy cap or coil top, loose wire connections onto coil, etc.

Many cheap Bling plug leads now are just carbonised string, their resistance is OK when new but they go downhill in 5 years or less. When they hit 5K ohm they are ready for the bin.
I like the Bosch inductive core leads, or the custom set that GR sells (similar wire).
These leads are around 1.8K ohm resistance new, and stay that way.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.