Green Cub Pilot
Member
I have a technical question regarding spark plugs and the best size to use on a Continental C90-12F. I am currently using Tempest plugs (which I am VERY pleased with) and when I bought them, the size that Aircraft Spruce suggested as the correct replacement for the ones I was currently using (Champion REM38E), were the UREM38E.
I realize that the letter/number nomenclature stands for the Resistor / Thread size / Heat Rating / and Electrode for that specific plug. I have had a number of different plugs numbers on my Cub over the years, and I also realize that once you get past the thread mount and electrode style, the real question is .What Heat Rating does one want to use?
The engine I had was a newly zero timed/rebuilt one and the rebuild company installed REM38E on there (38 being the Heat Rating, as the best fit for the engine/airplane.
When I replaced those with Tempest plugs, Aircraft Spruce recommended the UREM-38E which I am now using. In the Aircraft Spruce catalog, they recommend the UREM40E plug for the C-90-12, but they have told me that if that one is out of stock, they also recommend the UREM38E (to them, it is really a question of which is in stock). They are both legal (as are many other types of plug heat numbers). Don Swords (Dons Dream Machines) recently recommended the Champion REM37BY as a really good plug for the C-90.
My 2 questions are:
1. What does the Heat Rating actually mean? (Im not afraid if you get technical since it will probably provide a real answer to me)
2. What is the better way to go for fuel efficiency and engine life; Higher or lower?
I am NOT interested in what size folks currently have on their Cub, but rather the technical aspect of choosing the best Heat Rating number when one chooses a plug.
Thanks for any help!
Jon
I realize that the letter/number nomenclature stands for the Resistor / Thread size / Heat Rating / and Electrode for that specific plug. I have had a number of different plugs numbers on my Cub over the years, and I also realize that once you get past the thread mount and electrode style, the real question is .What Heat Rating does one want to use?
The engine I had was a newly zero timed/rebuilt one and the rebuild company installed REM38E on there (38 being the Heat Rating, as the best fit for the engine/airplane.
When I replaced those with Tempest plugs, Aircraft Spruce recommended the UREM-38E which I am now using. In the Aircraft Spruce catalog, they recommend the UREM40E plug for the C-90-12, but they have told me that if that one is out of stock, they also recommend the UREM38E (to them, it is really a question of which is in stock). They are both legal (as are many other types of plug heat numbers). Don Swords (Dons Dream Machines) recently recommended the Champion REM37BY as a really good plug for the C-90.
My 2 questions are:
1. What does the Heat Rating actually mean? (Im not afraid if you get technical since it will probably provide a real answer to me)
2. What is the better way to go for fuel efficiency and engine life; Higher or lower?
I am NOT interested in what size folks currently have on their Cub, but rather the technical aspect of choosing the best Heat Rating number when one chooses a plug.
Thanks for any help!
Jon
