Spark plug size for compression tester?

[_brad_]

I need to know what size the L77JC4 plug is at the thread.

Going to buy a compression tester today but need to what size adapter I need.

1977 Evinrude 70 HP

Thanks

 

[WillyBWright]

Re: Spark plug size for compression tester?

14mm

And here you thought all along the your sparkplug had inch dimensions. They are 14mm threads and the wrench for it is a 21mm (virtually the same as a 13/16). Other smaller sparkplugs are 12mm and commmonly use a 16mm wrench (virtually the same as a 5/8). Champion, NGK, whatever. We've been putting metric parts in our inch outboard motors for a very very long time.

 

[_brad_]

Re: Spark plug size for compression tester?

Excellent! Thank you!

 

[tashasdaddy]

Re: Spark plug size for compression tester?

most have the adaper for both standard size plugs. i have one similar to this. http://www.mattstools.com/compression-tester-p-2210.html

i can't believe i could not find one in the iboats store.

 

[_brad_]

Re: Spark plug size for compression tester?

Great, thanks for all the help! I was thinking it was 14mm but wanted to be sure.

First time buying one.