Spark plugs

[mlander]

7/8"-18 1" RB114-1 [color:"green"] COLD - This is a number of the BG sparkplug with a 1" reach but I know nothing about it as I just ran the name up on the Internet.

Edit Dec. 10-2006

http://www.bgservice.com/index.html

M.L. Anderson

[Ivan Saxton]

Thank you for the tip on BG. I had never seen or heard of them apart from the ones my father and now I have had since 1946. I guess this just shows I am ignorant of aircraft. I had no difficulty locating the source in West Palm Beach. I'll chase a set of those 1" reach 7/8 plugs to try after I finish making corebox and pattern to make my own pistons for the Mercer in near future.

Harking back to the original question, I'll try on the next cool day to clean an old fouled plug with ethanol. I dont know why I never remembered this before, but the old method to remove carbon deposits in cylinders was to burn it out with metho with piston on TDC on compression stroke. If this works with the cylinder it should be just as good for the plug.

Ivan Saxton

[mlander]

Ivan;

I am very curious about the original sparkplugs on the Mercers if you have the type and numbers I will look them up on Donald McKinsey?s price list and see if they correspond to any other sparkplugs. His list is very good but do not include the Reach which you have provided the .950? dimension in any case. He must have one difficult time finding the type of sparkplug as many of the old plugs do not have the numbers on the insulator or on the shell.

M.L. Anderson

[Ivan Saxton]

I have no information at all on what the original spark plugs were. Every one in engines I have wery just short reach plugs screwed in the inch holes. Best person to ask may be Fred Hoch, because he probably has most shared wisdom from Ralph Buckley, but I don't know if he has Internet. Last time I wanted to ring him I had trouble finding the altered area code. Stan Smith might be another good one to ask, and I can probably get onto his email address from John Hancox, another Mercer owner here who has visited him and keeps in touch.

Ivan Saxton

[mlander]

To Ivan; I was in communication with John Gillette who owns a Mercer and he was able to give me the Champion number of one of the sparkplugs he uses for his Mercer which is the one listed below, he also uses a Autolite 3076. The Autolite is a 5/8? reach but please note the reach on the Champion C97B which is 1-1/4? reach.

C97B = 7/8"-18 t.p.i. thread, <span style="text-decoration: underline">1-1/4" reach</span> 1-1/4" reach, 1-1/8" hex, standard design, standard coil. $33.88.

Edit;Dec.-21-2006

Ivan;

I believe I have found the answer to the whole sparkplug problem and that is,? Just what was the original sparkplug which was very likely a Stitt #19 or 17E or 17Ex?. This sparkplug was replaced with a Champion #C97B as this is the only sparkplug that even comes close to putting the spark out into the actual combustion chamber.? The 1.05? dimension you believe is correct may very well be off .200? it is very likely 1.250? either that or the spark is generated .200? deeper into the combustion chamber. This sounds correct to me as this is a low compression engine.

There is no way I can see of you coming close to this with a BG plug. The only to find the very first sparkplug in the first Mercer is to find a shop manual or owner?s manual or something of that kind of Champion catalog of that period. The only other sparkplug that is that long is a Delco AC # 17.

M.L. Anderson <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

[mlander]

After getting some information on the 7/8-18 sparkplugs from John Gillette in Ohio I have gone to some lengths to see if there isn't more of the sparkplugs available. Please note the prices.and the various reaches.

7/8?-18 ALL. PLUG TYPE.. REACH......... HEX.............. PRICE EACH

510............... W10............. .625?............ 15/16?.......... $6.51

569............... W14............. .625?............ 15/?6?............ $6.51

561............... W16Y........... .625?............ 15/16?.......... $6.51

518............... W18............. .625?............ 15/16?.......... $6.51

520............... W20............. .625"............ 15/16?.......... $6.51

228............... RW77PP....... 1.000?.......... 15/16?.......... $46.52

201............... W77N........... .625?............ 15/16?.......... $18.15.......... 4 GROUND ELECTRODES

539............... W77N........... .625?............ 15/16?.......... $18.15............................... ?

631............... RW78N......... .860?............ 15/16?.......... $32.00............................... ?

553............... RW80N......... .625?............ 1.000?.......... $32.00............................... ?

200............... RW80N......... .625?............ 1.000?.......... $32.00............................... ?

1207............. RW80PP....... .625?............ 15/16?.......... ?.........................................

580............... W80N........... .600?............ 15/16?.......... $18.15.......... 4 GROUND ELECTRODES

202............... W80N........... .600?............ 15/16?.......... $18.15...................................

582............... RW82P......... .625?............ 15/16?.......... $52.98...................................

559............... RW83F......... .625?............ 1.000?.......... $39.36.......... 3 GROUND ELECTRODES

545.............. W85N........... .600?............ 15/16?.......... $18.15.......... 4 GROUND ELECTRODES

203............... W85N........... .600?............ 15/16?.......... $18.15.......... 4 GROUND ELECTRODES

589............... W89D........... .625?............ 15/16?.......... $7.99............ PROTRUDING NOSE

595............... C95F............ .625?............ 1-1/8?........... $23.29.......... 3 GROUND ELECTRODES

562............... W95D........... .625?............ 15/16?.......... $15.55.......... PROTRUDING NOSE

513............... C97B............ .1.250?..........1-1/8?........... $33.88.......... 2 GROUND ELECTRODES

M.L. Anderson

[Ivan Saxton]

I do appreciate you taking such trouble on this. Just looking at your last list above, it indicates C97B at 5/8"reach, which differs from the previous post; and shows RW77PP as the only 1" reach. The BG web site I looked at did show a 1" reach 7/8-18 plug that was automotive type rather than the aircraft type where the connection fits right down inside the plug body. I have no idea what heat range would be necessary or desireable, but the BG plug is cold.

My measurements are accurate for my engines. 4297 is 1918 Series 4,and 5407 is 1919 Series 5, both with the same longer type conrods. (# might be 5402,because I forgot to double check earlier).

I understand the 1915 block castings were different in some ways. The bloke who neeeds spark plugs first is John Hancox, who is making new conrods and pistons now for his Series 6. These Rochester Trego engines are dual gnition, needing 12 plugs each engine, which runs up quickly in cost. Having exposed thread on a spark plug in the combustion chamber is not ideal practice. The carbon deposit is not quite the graphite that would lubricate the removal.

I surmise that you maybe collect spark plugs. If this is correct I shall send you examples of what I have around including those Legget's "Dynamic" 10mm plugs made here. I would be surprised if they were common in collections in USA. You would have to communicate a postal address.

All the best, et cetera,

Ivan

[mlander]

John: I am glad you checked the reach as I made a mistake, after you go thru as many plugs as I have to make up this list it isn't surprising that that happened.

I do not need any more plugs as the ones I have are significant for my purposes. Donald McKinsey is sending me one more which he says is the one I need to complete my study of the 7-8?-18 plugs. I have almost determined that McKinsey is completely correct in his telling me that the Heat Range ?theory? was not accepted until the 1925-1930 period altho whether or not it was by Bosch is questionable. Yours for a fun time; Marion L. Anderson <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" />

Added a sketch I hope!