Spark plugs
02-20-2011, 02:17 PM
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Spark plugs
Snowed in today, bored, decided to measure some spark plugs
CM6 OAL 1.409 top to bottom of side electrode
Hex .545
Porcelain diameter .312
Top of plug to bottom face without washer .991
Champion Y82 Oal 1.419
Hex .551
Porcelain .310
Top to bottom face without washer .981
Denso U20MU OAL 1.421
Hex .546
Porcelain .312
Top to bottom face without washer .996
Rimfire 1/4-32 OAL .974
Top to washer face .731
porcelain .179
Hex .311
RC EXL 1/4-32 OAL 1.044
Hex .315
top to washer face -795
porcelain .179
These dimensions are pretty much well within manufacturing tolerances and will vary slightly....There is no reason any one will fit the RC EXL cap any better than another, just PUSH...I didn't gap any of the plugs, the OAL will reflect this, but not much...
As an example, one CM6 was 1.389, another was 1.409
Length of a CM6/Rc EXL cap 1.262 top of cap to cylinder
Same for 1/4-32 plug screwed into the 14mm adatper 1.069
BPMR6F top of cap to cylinder, 1.587
The "reach" of the Denso is longest at .339 from washer face to flat bottom of the plug not counting the side electrode
Champ and NGK are the same, .319
CM6 OAL 1.409 top to bottom of side electrode
Hex .545
Porcelain diameter .312
Top of plug to bottom face without washer .991
Champion Y82 Oal 1.419
Hex .551
Porcelain .310
Top to bottom face without washer .981
Denso U20MU OAL 1.421
Hex .546
Porcelain .312
Top to bottom face without washer .996
Rimfire 1/4-32 OAL .974
Top to washer face .731
porcelain .179
Hex .311
RC EXL 1/4-32 OAL 1.044
Hex .315
top to washer face -795
porcelain .179
These dimensions are pretty much well within manufacturing tolerances and will vary slightly....There is no reason any one will fit the RC EXL cap any better than another, just PUSH...I didn't gap any of the plugs, the OAL will reflect this, but not much...
As an example, one CM6 was 1.389, another was 1.409
Length of a CM6/Rc EXL cap 1.262 top of cap to cylinder
Same for 1/4-32 plug screwed into the 14mm adatper 1.069
BPMR6F top of cap to cylinder, 1.587
The "reach" of the Denso is longest at .339 from washer face to flat bottom of the plug not counting the side electrode
Champ and NGK are the same, .319
02-20-2011, 03:14 PM
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RE: Spark plugs
ORIGINAL: Antique
Snowed in today, bored, decided to measure some spark plugs
CM6 OAL 1.409 top to bottom of side electrode
Hex .545
Porcelain diameter .312
Top of plug to bottom face without washer .991
Champion Y82 Oal 1.419
Hex .551
Porcelain .310
Top to bottom face without washer .981
Snowed in today, bored, decided to measure some spark plugs
CM6 OAL 1.409 top to bottom of side electrode
Hex .545
Porcelain diameter .312
Top of plug to bottom face without washer .991
Champion Y82 Oal 1.419
Hex .551
Porcelain .310
Top to bottom face without washer .981
hex is bigger than the NGK/CM-6, and that the plug cap won't fit.
Interesting details you came up with!
02-20-2011, 03:24 PM
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RE: Spark plugs
ORIGINAL: STUKA BARRY
When were you dial calipers last calibrated? I see a .0000001 descepancy already.....
When were you dial calipers last calibrated? I see a .0000001 descepancy already.....
02-20-2011, 05:44 PM
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RE: Spark plugs
The hex IS bigger, but not enough to cause a probem...Use some silicone spray or WD 40 in the cap and push hard....
The width of the hex on the Champion plug is .167, the CM6 is .112. the Denso is .114..
The width of the hex on the Champion plug is .167, the CM6 is .112. the Denso is .114..
02-21-2011, 09:16 AM
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RE: Spark plugs
ORIGINAL: Antique
The width of the hex on the Champion plug is .167, the CM6 is .112. the Denso is .114..
The width of the hex on the Champion plug is .167, the CM6 is .112. the Denso is .114..
Just curious as others may ask about such. Having both might be beneficial.
04-26-2011, 02:57 PM
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RE: Spark plugs
ORIGINAL: Antique
*OAL=Over All Length*
NGK/CM-6 OAL 1.409 (top to bottom of side electrode)
Hex (across flats) .545
Hex (width of) .112
Hex (point -to- point) .617
Porcelain diameter .312
Top of plug to bottom face without washer .991
Champion Y82 OAl 1.419
Hex (across flats) .551
Hex (width of) .167
Hex (point -to- point) .626
Porcelain .310
Top to bottom face without washer .981
Denso U20MU OAL 1.421
Hex (across flats).546
Hex (width of) .114
Hex (point -to- point) .620
Porcelain .312
Top to bottom face without washer .996
- - - - - - - - - - - - - - - - - - - - - - - - -
Rimfire 1/4-32 OAL .974
Top to washer face .731
Porcelain .179
Hex (across flats) .311
Hex (point -to- point) .353
RC EXL 1/4-32 OAL 1.044
Top to washer face .795
Porcelain .179
Hex (across flats) .315
Hex (point -to- point) .351
- - - - - - - - - - - - - - - - - - - - - - - - -
These dimensions are pretty much well within manufacturing tolerances and will vary slightly.
There is no reason any one will fit the RC EXL cap any better than another, just TWIST & PUSH!
I didn't gap any of the plugs, the OAL will reflect this, but not much.
As an example, one NGK/CM-6 was 1.389, another was 1.409
Length of a Rc EXL cap (for a NGK/CM-6) 1.262 top of cap to cylinder
Same for 1/4-32 plug screwed into the 14mm adapter 1.069
BPMR6F top of cap to cylinder, 1.587
The "reach" of the Denso is longest at .339 from washer face to flat bottom of the plug not
counting the side electrode. Champ and NGK/CM-6 are the same, .319
*OAL=Over All Length*
NGK/CM-6 OAL 1.409 (top to bottom of side electrode)
Hex (across flats) .545
Hex (width of) .112
Hex (point -to- point) .617
Porcelain diameter .312
Top of plug to bottom face without washer .991
Champion Y82 OAl 1.419
Hex (across flats) .551
Hex (width of) .167
Hex (point -to- point) .626
Porcelain .310
Top to bottom face without washer .981
Denso U20MU OAL 1.421
Hex (across flats).546
Hex (width of) .114
Hex (point -to- point) .620
Porcelain .312
Top to bottom face without washer .996
- - - - - - - - - - - - - - - - - - - - - - - - -
Rimfire 1/4-32 OAL .974
Top to washer face .731
Porcelain .179
Hex (across flats) .311
Hex (point -to- point) .353
RC EXL 1/4-32 OAL 1.044
Top to washer face .795
Porcelain .179
Hex (across flats) .315
Hex (point -to- point) .351
- - - - - - - - - - - - - - - - - - - - - - - - -
These dimensions are pretty much well within manufacturing tolerances and will vary slightly.
There is no reason any one will fit the RC EXL cap any better than another, just TWIST & PUSH!
I didn't gap any of the plugs, the OAL will reflect this, but not much.
As an example, one NGK/CM-6 was 1.389, another was 1.409
Length of a Rc EXL cap (for a NGK/CM-6) 1.262 top of cap to cylinder
Same for 1/4-32 plug screwed into the 14mm adapter 1.069
BPMR6F top of cap to cylinder, 1.587
The "reach" of the Denso is longest at .339 from washer face to flat bottom of the plug not
counting the side electrode. Champ and NGK/CM-6 are the same, .319
