Author Topic: Spark plugs for TS  (Read 7508 times)

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Offline Ian

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Spark plugs for TS
« on: 15 Jun 2009 at 23:25 »
Folks, we were having a discussion about spark plus for the 2.75HP Douglas on the weekend. The 18mm plugs that are available now do not have lon enough thread for the standard valve caps and are actually quite recessed. Most of us use the NGK A6 or AB6 plugs. I am sure that the combustion would be better if the plug actually projected below the cap.

One option is obviously to make up valve caps with thread for 14mm plugs and use the extended ones - what do other forum members do ? Has anyone made up batches of caps for 14mm plugs ?

Offline podge

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Re: Spark plugs for TS
« Reply #1 on: 16 Jun 2009 at 08:04 »
On my 1932 A31, I have 18 mm to 14 mm reducers fitted, and use a long reach spark plug. I use NGK B7ES and the bike has run well for the past year. However I am told that a softer plug would be better such as the NGK B6ES or B5ES, but the B7ES's were the only ones that I could find at the time.

Paul

Offline Ian

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Re: Spark plugs for TS
« Reply #2 on: 16 Jun 2009 at 23:09 »
Paul, where did you source the reducers ?

Offline Alan Cun

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Re: Spark plugs for TS
« Reply #3 on: 17 Jun 2009 at 09:35 »
Hello Ian, Years ago you could buy adaptors from REPCO here in Aust. In the past I have made them up by parting of the base of an 18 mill plug. The ceramic centre drops out and it is just a matter of taping a 14 mil thread.

Now back to the original statement of the plug going down far enough in the plug thread can't see it as a problem. Something that keeps coming to mind now, I am not even sure which heads it was DT, OB, S1 where the plug thread didn't go all the way through but there was a very small hole around one eighth into the combustion chamber. The theory being to prevent plug fouling. Now I could go to the shed and check all my spare heads but I feel the idea was discarded by previous users and all would probably have been modified.

The last para is certainly a very distant memory and can't remember if it was a personal or a comment from the New Conrod Doug Magazine.

Finally as previously stated up here where it much hotter riding conditions we use the NGK 7 taper base plug from the old Ford Windsor (I think) . My E 29 has done over 3 thou of hard riding and I can't remember even checking the plugs in 20 years or more. regards Alan

After a couple of hours after posting this I began to think>>>> one thing about using an 18 mil plug is the extra air space around the electrode and with our poor quality fuels of today and possible plug fouling this should be considered. I vaguely remember using 14 mil plugs with my home made adaptors in the B29 also I used many variations of 14 's in the SW 600 until I stopped disentigrating rear pistons in both models. This I contribute to the change to NGK 7's. Alan
« Last Edit: 17 Jun 2009 at 11:52 by Alan Cun »

Offline podge

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Re: Spark plugs for TS
« Reply #4 on: 17 Jun 2009 at 22:56 »
Hi Ian

The bike had been partially restored when I acquired it a year ago, complete with reducers. It looks as if they were turned up using a piece of hex stainless steel bar. Tomorrow I will be at Brooklands Motor Museum in Weybridge, UK, and will ask the lads if they know of a UK supplier of reducers. I will get back to you.

Regards

Paul

Offline Ian

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Re: Spark plugs for TS
« Reply #5 on: 17 Jun 2009 at 23:13 »
Thanks Alan. The fouling of the plugs is not an issue on mine. What I was thinking is that the 2.75hp needs all the help it can get to run nicely !! With the plugs hidden up the hole in the valve cap there has to be some impact on the burn of the fuel mixture - compared to sparking out in the open - even effectively changing the timing a bit.

As far as the heat range of the plugs is concerned the 6 seems OK - but as is normal one cylinder runs hotter than the other so I would actually like to run a 7 in that one - I do that on the OC. With the OC when we did the motor we modified one of the sets of heads I have to take normal 14mm plugs which gives a much wider availability - I run a 5 on one and a 7 on the other cylinder on that one !

What effect do you think the extra air space round the 18mm would have ? hotter or colder ?

Offline Doug

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Re: Spark plugs for TS
« Reply #6 on: 18 Jun 2009 at 03:01 »
When running with the anti-oil fouling pocket heads, one does need to use more advance for the ignition. My '34 OHV seemed to be happy with 35 degrees advance. Heads that have been drilled out have faster ignition and so should be set up with less advance and I have heard numbers closer to 25 being found suitable.

I can not see that as being a problem with the 2-3/4hp engines though, as they do not run fast enough that ignition speed should be a problem. So if the plug is recessed and you have timed it a little early, no big deal. The twenty extra nano-seconds that it takes to light the mixture is not going to stop the engine from spinning up to eight thousand RPM, because the crank and rods will break long before that point is reached!

One thing I found with my old Ford is the ground electrode tended to shroud the spark, and there was not enough turbulence in the low compression and minimal squish head to get the mixture lit off to a good start at slow speeds. Cutting the ground electrode short and bending it down to the side of the center electrode made for improved low speed running. Of course, this severely limits your re-gaping options!

-Doug

Offline podge

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Re: Spark plugs for TS
« Reply #7 on: 18 Jun 2009 at 11:33 »
Hi Ian

As promised I talked to the Brooklands boys today. The source of 18 mm/14 mm reducers is :-

The Green Spark Plug Co,
Mocliffe,
29 Northwich Road,
Cranage,
Cheshire CW4 8HL
England.

Online: www.gsparkplug.com/products
Phone: 00441477 532 317 (9 - 5 Mon-Fri)

They have them in stock at 3.50 each

Hope this helps

Regards

Paul

Offline Ian

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Re: Spark plugs for TS
« Reply #8 on: 18 Jun 2009 at 23:35 »
Thanks Paul !

Offline Alan Cun

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Re: Spark plugs for TS
« Reply #9 on: 19 Jun 2009 at 09:01 »
Hello Ian, Not sure what difference there would be in the area around the electrode. As for making the TS go better Kevin Cass down your way made improved conrods for his CW before heading off for that round Aust trip. I can also remember him making a set of rods for the chap you got the OC from.

After my first restorations B29, EW and E 29, I was little put off at restoring a TS engine and as there was a spare 80 serial number stationary engine on the shelf I slotted it straight into the frame (changing the base and flywheel of course) I did however have to dispose of the half timing gear and oiling system and fit normal TS cover as left hand turns created extra smoke.
I did a fair few miles on the TS but never figured it loosing power after about 15 miles. Maybe either from the single cable carb from the stationary or the original Mag breaking down. Will get back to it one day?
One thing I have done to it is to fit one inch pipes about two feet long into each cylinder and jam tin style muffler by the rear axle.(Zoom Zoom exhaust?) power gain ? maybe.

I always considered the TS as a bike you like to ride off into the distance and depending how much you enjoy the ride depends on when you  finally do a U turn and ride back.
regards Alan

Offline Ian

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Re: Spark plugs for TS
« Reply #10 on: 19 Jun 2009 at 23:33 »
Alan, yes the TS is great ! I found that mine was losing power after a while - that is now fixed with the heated inlet - was carby ice (or at least very cold )

 

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