Spark Plug Troubleshooting

[Bob_Belville]

12 minutes ago, Rich said:

I will be replacing my massive electrode plugs with fine wire plugs soon. I have the IO550 in my Ovation 2. I have been unable to find the difference between the Tempest URHB32S and URHB36S. Can anyone advise me on which would be best and why? Thank you in advance for any assistance.

 

Not best - the "32" has the 5/8" wire nut, the "36" has the 3/4". http://www.aircraftspruce.com/catalog/pdf/TempestAppGuideV3-07-01-13.pdf

[Rich]

Just now, Bob_Belville said:

Not best - the "32" has the 5/8" wire nut, the "36" has the 3/4". http://www.aircraftspruce.com/catalog/pdf/TempestAppGuideV3-07-01-13.pdf

So, I assume that the 36S would be better?

 

[Bob_Belville]

1 minute ago, Rich said:

So, I assume that the 36S would be better?

 

No. it is a matter of what your harness wire nut is. Either 5/8-24 or 3/4-20. Check out the bottom of the columns of the app guide.

 

[Rich]

Just now, Bob_Belville said:

No. it is a matter of what your harness wire nut is. Either 5/8-24 or 3/4-20.

AHH. So I just have to remove it and measure. I still don't understand as the Tempest guide says the RHB's have 3/4" while the REB and REM have 5/8"

[Bob_Belville]

Just now, Rich said:

AHH. So I just have to remove it and measure. I still don't understand as the Tempest guide says the RHB's have 3/4" while the REB and REM have 5/8"

You're right, I misread the line for you IO550. It appears both the fine wire plugs for your engine are 3/4"-24. The 32 and 36 are heat ratings, the higher the number the higher the heat rating. Again, one is not better than the other, it depends upon what the application needs. 

 

http://www.aircraftspruce.com/catalog/pdf/tempestplugmaint.pdf

The heat rating of a plug measures the ability of a spark plug to transfer heat from the spark electrodes and insulator nose to the cylinder and engine cooling system while resisting carbon fouling. TEMPEST® Aviation Spark Plugs are available in a range of heat ratings to meet various engine and operational requirements. The use of terms “hot” or “cold” in reference to spark plugs is often a source of confusion when selecting the proper spark plug for an application. For a given engine series, hot plugs are usually specified for the lower horsepower engines and cold plugs for the higher horsepower engines. The terms actually refer to the plug’s ability to dissipate heat. By definition, a cold heat range plug dissipates heat more rapidly. Likewise, a hot heat range plug has a slower rate of heat dissipation. The primary factor in whether a plug is hot or cold is the length of the insulator assembly core nose. Hot plugs have relatively long insulator noses and, therefore, a long heat transfer path. Cold plugs have relatively short noses and thus transfer heat more quickly. All other parts of a part number being equal, you can tell if an TEMPEST® Aviation Spark Plug is hotter or colder heat range by the numbers in the middle of the part number. For instance, comparing a UREM40E with a UREM38E, the UREM40E is a hotter plug because “40” is larger than “38”

[Rich]

5 minutes ago, Bob_Belville said:

You're right, I misread the line for you IO550. It appears both the fine wire plugs for your engine are 3/4"-24. The 32 and 36 are heat ratings, the higher the number the higher the heat rating. Again, one is not better than the other, it depends upon what the application needs. 

 

http://www.aircraftspruce.com/catalog/pdf/tempestplugmaint.pdf

The heat rating of a plug measures the ability of a spark plug to transfer heat from the spark electrodes and insulator nose to the cylinder and engine cooling system while resisting carbon fouling. TEMPEST® Aviation Spark Plugs are available in a range of heat ratings to meet various engine and operational requirements. The use of terms “hot” or “cold” in reference to spark plugs is often a source of confusion when selecting the proper spark plug for an application. For a given engine series, hot plugs are usually specified for the lower horsepower engines and cold plugs for the higher horsepower engines. The terms actually refer to the plug’s ability to dissipate heat. By definition, a cold heat range plug dissipates heat more rapidly. Likewise, a hot heat range plug has a slower rate of heat dissipation. The primary factor in whether a plug is hot or cold is the length of the insulator assembly core nose. Hot plugs have relatively long insulator noses and, therefore, a long heat transfer path. Cold plugs have relatively short noses and thus transfer heat more quickly. All other parts of a part number being equal, you can tell if an TEMPEST® Aviation Spark Plug is hotter or colder heat range by the numbers in the middle of the part number. For instance, comparing a UREM40E with a UREM38E, the UREM40E is a hotter plug because “40” is larger than “38”

Thank you so much Bob. I believe that I need to go with the cooler of the plugs- I think that's the 32S. Safe flying!

[Bob_Belville]

Just now, Rich said:

Thank you so much Bob. I believe that I need to go with the cooler of the plugs- I think that's the 32S. Safe flying!

That seems right to me but I have UREM38S in my IO360 so maybe someone with experience with your engine will chime in. 

[carusoam]

Do spark plugs ever get mentioned in the POH?

Reading the O's POH it references reading the engine manufacture's manual that is amazingly not part of the airframe document set. 

Best regards,

-a-

[211º]

I changed to fine wire plugs about two weeks ago. Wow! Hot starts require one or two blades instead of 15 to 20. LOP feels better too. Old massive appear to have been there “for a while or so”.

I now start and taxi my plane to/from fueling instead of pushing and pulling. Nice!