18mm to 14mm Spark Plug Thread Adapter..

[mercguy]

I have seen these used in Yamatos. My question is what spark plug works the best, as I figure you will have to run a colder plug than the normal B9ES used in the 14MM head???? Is there anything else recommended? I assume you might also have to make sure the adaptor is flush on the inside of the head? I have also heard of a "speed secret" that says to let the adaptor extend a little bit into the head? Also, I have not read anything that says these are legal or illegal to use in stock racing????

http://eastwood.com/shopping/product...roductID=11418

[Sonny]

plugs

The smaller 14mm plugs are avalible in more heat ranges and are much cheaper. The 18mm plugs last longer. As far as This threaded nut adapter thing goes, you are allowed 26cc's for an 18mm head and 25.5cc's for a 14mm head anything elts is cheating.

[bill boyes]

I have seen these used in Yamatos. My question is what spark plug works the best, as I figure you will have to run a colder plug than the normal B9ES used in the 14MM head???? Is there anything else recommended? I assume you might also have to make sure the adaptor is flush on the inside of the head? I have also heard of a "speed secret" that says to let the adaptor extend a little bit into the head? Also, I have not read anything that says these are legal or illegal to use in stock racing????

http://eastwood.com/shopping/product...roductID=11418

I use them in the Yamatos with the 18mm heads. Champion xxx53 and xxx55 plugs. don't remember all the nbrs(old age) the rule is when cc's are taken remove the insert. So some guys leave them long. However, the risk is burning a piston. Ask Wart and Hewson. Gollor and TJ says cut them off.

[mercguy]

Yamato spark plugs......

The smaller 14mm plugs are avalible in more heat ranges and are much cheaper. The 18mm plugs last longer. As far as This threaded nut adapter thing goes, you are allowed 26cc's for an 18mm head and 25.5cc's for a 14mm head anything elts is cheating.

that is why I want to make sure they are legal, as "cheating" is BS!!!!! Has anyone located a spark plug other than the "10" that is for the 18MM head that is colder?? As to the cost difference, I get a really good deal on the "10"'s, so there is not a DRAMATIC price difference between the 2 different plugs, but still costs close to 3x.

also, have there been any noticeable diiferences between the new irridium plug versus the standard B9ES used in the 14MM heads? I use the standard plugs, since they are changed pretty much every race....

[mercguy]

I use them in the Yamatos with the 18mm heads. Champion xxx53 and xxx55 plugs. don't remember all the nbrs(old age) the rule is when cc's are taken remove the insert. So some guys leave them long. However, the risk is burning a piston. Ask Wart and Hewson. Gollor and TJ says cut them off.

thanks Bill for the info. One of those guys was the one with the "speed secret". I figured it might be true, considering all the "EXPANSIVE" testing Wart does with all those gauges!! The dashes of the boats he test resemble the dash of an airplane!!!!!

[bill boyes]

I don't why you would want a plug cooler than a 10. We haver never had a need. Even Bakersfield at 107 degrees. Remember Champ pulgs heat range nbrs are opposite NKG's. i.e. an NKG 9 is warmer than a 10. thereas a Champ 55 is warmer than a 53. Some Yamato owners like the inserts some don't. A spreed advantage ???? I have inserts in my trailer you can try them at Bakerfield if you like. BTW that is a good price.

[mercguy]

I don't why you would want a plug cooler than a 10. We haver never had a need. Even Bakersfield at 107 degrees. Remember Champ pulgs heat range nbrs are opposite NKG's. i.e. an NKG 9 is warmer than a 10. thereas a Champ 55 is warmer than a 53. Some Yamato owners like the inserts some don't. A spreed advantage ???? I have inserts in my trailer you can try them at Bakerfield if you like. BTW that is a good price.

oops, your right Bill. I was trying to see if there was a HOTTER plug available than the 10. Wouldn't it be nice if all the spark plug manufacturers would use the same system to rate the temp of their plugs?

[bill boyes]

I run NKG 9's and 10's in my yamato's with the 14mm heads. Never had a need for an 8. I am sure they are available tho. One of my 302's came out of the box with 18mm NKG 91/2. That was a real nice plug. Never seen them since.

[paul jillings]

Yamato Cyl. Heads

Guys, the heads with 14mm threads are avaiable from Yamato (UK) and I guess that your dealers would have them too...these are correctly cc'd to suit the different plugs and are legal for OSY 400........

Over here we always ran NGK plugs, 9's or 10's and the 9.5's were scarce.

[DougMc]

I use the standard plugs, since they are changed pretty much every race....

Do most people change plugs every race?

[C Stock Racer]

Daren, I have used 10's and 95's and I can't tell the difference. The 10's are all I can find now. George