Mac engine spark plugs

[GK2]

Please tell me the available types of over the counter spark plugs that can be used for the Mac engine, 72 hp. Spark plugs I can get from the autoparts store. Thank you.

 

[Gyro28866]

Most of the auto parts store do not stock them any more. The only one local is an "Advanced Auto", and they have to order them.
Champion D4 (504)
I normally get about 6-8 hours of good run time.
When the starting gets a little harder it is time to change, all of them.
It is unnerving to be out and have one stop firing. I lost two at one time on a flight to check my cattle about 12 miles from the airport. I was about 3 miles out and lost two, it was a slow steady decent at full throttle position. I made the end of the runway with about 50 feet to spare. I do not temp the Mac Attack Demons anymore.

 

[Brent Drake]

Most of the auto parts store do not stock them any more. The only one local is an "Advanced Auto", and they have to order them.
Champion D4 (504)
I normally get about 6-8 hours of good run time.
When the starting gets a little harder it is time to change, all of them.
It is unnerving to be out and have one stop firing. I lost two at one time on a flight to check my cattle about 12 miles from the airport. I was about 3 miles out and lost two, it was a slow steady decent at full throttle position. I made the end of the runway with about 50 feet to spare. I do not temp the Mac Attack Demons anymore.

Dave, I have many hours on my Mac. I've never changed a plug, Have about 25+ this summer with no problems. I just clean them every spring.

Does your Mac start easy?
What oil Mix do you use?
What oil type doe you use?

 

[Gyro28866]

Brent:
I have the CDI from Rick Whittridge, and yes it starts easy.
16oz/5gal
Blue Marbles

Even when I was using petro based oil, the plugs did not last too long. Rick commented that he gets less that 10 hours on a set. I know when the cold start is more that 4 or 5 pulls of the prop, it is getting close to time to change the plugs.

 

[GK2]

I was told the NGK1210 A-8 could be used in the Mac but I have not found those new locally yet.

 

[Brent Drake]

I run Amsoil Synthetic smokeless.
10oz to 5 gal. I think that is about 65-1 ratio.
The originals would run them 100-1 oil.
I do run the original magneto.
Always starts on first or second flip.

 

[Brent Drake]

I do know Gary runs 8oz to 5 gal in his. 80-1

 

[dabkb2]

I have to agree, if you use champion auto plugs after about 10 hours it will get hard to start. I have been using Champion REM 38s-a aircraft plugs for over 100 hours and never had a problem.

 

[Mark Spies]

I have been using Champion 509 or D9
Blue Marble 14oz - 5 gal
Rick's CDI
Hit the switch...starts right up...

 

[gyroplanes]

duplicated, sorry.

 

[gyroplanes]

I am trusting to memory here, but I believe I used to run Motorcraft B3X plugs in my 90 MAC. Never had any problems in 10 years. The B3X had to be ordered, but they are a 2 stroke plug. I think Prater and Parsons recommended them back then.

Champion D9J also rings a bell.

 

[Passin' Thru]

Champion D9J also rings a bell.

This was the plug I used most in my Macs.