80" Chief Spark Plugs

[indianstan]

Hey guys,
Just finishing up a rebuild on my '52 Chief and was curious as to what spark plugs other 80" Chief owners are using and any recommendations. I have been running 4093 Autolite's since the late 1980's, mainly because I had a box of them, and never had any problems, but thought I'd ask if there may be something better to use. I saw or heard somewhere that AC R42XLS were the best for the 80's as the longer reach puts the spark closer to the mix, however I'm a little skeptical, but intrested. Any recommendations anybody?
Thanks much,
Stan

[starklite]

I would have to recommend our Indian Script Plug - We run them in all of our restorations with great success:


Get that last point on your restorations using our latest addition for your Indian Motorcycle. We have reproduced the Indian "C" Script Spark Plug, complete with a collector Indian Script Box.
The "C" is the most common heat range used on our Indian Motorcycles
This is a 1/2" reach plug (Indian originally used a 3/8" reach). It is completely interchangeable with the 3/8 plugs on all heads.
The plug is equivalant to a NGK B7HS or Champion J6.
We designed this plug to be used! Not placed on a shelf and looked at. Although, you may want to order a set for your memorabilia collection!
Sold Each

Sincerely,
Gary Stark
Starklite Cycle

[PRG]

Howdy Stan,

The purists may wince but with modern rings and superior oil control there is no need to run a short reach J6 type plug - essentially enshrouding your spark from the combustion chamber.

In my hot rod 48 Chiefwith higher compression 80ci I run an NGK BP7ES, unmodified as these heads have full depth brass plug inserts. On the stock 74ci of the 46 Chief with short inserts I merely turn off the unneeded threads to prevent any carbon build up that might compromise their removal later.

The plug base is flush with the head surface leaving the electrode fully exposed. With Clyde Crouch's electronic ignition and more accurate fuel control through use of the latest foam floats, one can run less advance and a slightly leaner mixture and have superior hot/cold starting, as some noted on the Indian Breakfast ride this year as the 46 is absolutely a one minimal-effort kick starter under all circumstances.

Not to get OT, but with a cleaner burn, you'll note better mileage, less of a tendency for your oil to contaminate so quickly and with copper gaskets for better heat dissipation a generally happier motor with less ring wear.

[D.A.Bagin]

Anysuggestions on what plug for my 4 ??

[PRG]

Howdy sir,

From your sig I see you have a 440: the answer would be anything that will make a spark to include a tazer as it's a totally different situation with these. You can search both here and at Caimag for lengthy missives on my fruitless search for the performance TRUTH with 38-42 motors....only to discover, as they say, it is what it is.

The long and the short of it is that I built my 441 with pretty much every mod available at the time and capped it off with raised compression, more advanced ignition and leaner mixture. It ran incredibly better around town and on the open road with tall gearing soared along at speeds not heretofore experienced. But, after slowing to a stop to savor the moment, turned the ignition off and it continued to sit there idling, now using glowing exhaust valves for ignition.

By the time I got its performance parameters the same in town and on the road in warm weather, most all of the above had been dialed out and I was back nearly to stock. You'll note your spark plugs are entirely shielded from the vulnerable exhaust valve area and angled so the flame front is aimed at the combustion chamber. I now concede they had good reason for that and thus run J6's in the 440 and Autolite 303's in the 441. These are way more happy plodding along than Chiefs which take to be wakened up far better.

[indianstan]

Peter,
Thanks much for your reply and spark plug recommendation. Maybe I'll get a set of the NGK's and a set of the Indian plugs from Gary and try them both out.
Best regards,
Stan

[indianstan]

Gary,
Thanks for your reply. I've been wondering how these would do in an 80". I understand these have a slightly longer reach than the old standards. Is that true? Thanks much.
Best regards,
Stan

[bikerdds]

I have been using original Champion J-6's in my 52 chief since it was built 7 years ago. Always starts on first hot kick. Modern J-6's work fine as well, but need blackening for period effect. No reason to re invent the wheel. Plugs come up on ebay and at meets. J-5's for 50-51, however, are tough to find, but the modern J-5 works fine and also needs to be blackened for effect.
I have also used the modern Indian C substitute that has nothing in common with original C plugs except the printing. They are taller and tougher to put a wrench on but work fine otherwise on a chief, but are not correct after 1948.
The longer reach has been mentioned by some motor builders as potentially hitting valves on four cylinder motors, but fine for chiefs. Use original reach plugs on a four to be safe. Early original [blue box] Champion H-10 non resistor plugs are recommended by some four motor builders as well. I have used Autolyte 303's, which are black based like originals and run great in my 41 four.
While I have used the modern C in my 41 four, they are subject to easier fouling than the Autolyte. I never had a valve issue, but have been warned about the longer reach. I like the look, but not the performance.
Many have wondered why the original plug hasn't been duplicated. Simple. Cost. The original Edison plugs were custom made for Indian, and there is no other plug that matches it. This is even more true for the A and B. If you want more reference information, see my article in the latest issue of the club mag on Indian plugs. Marty