What spark plug are you running in your 200?

[aribert]

I have a 78 200 smog motor in my '61. The long block is bone stock, just under 60K miles on it. The engine pings on hard accelleration. Even after running midgrade gas (91 Octane) there is no change in the pinging. Nosing around, I have come on several posts on other marque lists that plugs have a significant effent on pinging (choose a cooler plug to reduce pinging). FWIW, I moved my narrow band O2 sensor & display into the Falcon and the enigne is rich when it is pinging (actually rich at all conditions except for running on the freeway at 70 mph where the A/F appears to be close to correct). I have played around with the timing a biot and it does not appear to have an effect on the pinging.

Out of curiosity, what plug (brand and P/N) do you have in your engine? Thanks

 

[flash_point01]

Autolite 45's i think. One step colder than stock. But thats with the DSII, and 14* advance

 

[wsa111]

The plug i like is NGK IRIDIUM IX WR51X stock #7510.

The NGK plug is the latest in technology, it has a pin center electrode which requires less voltage to fire & the center electrode is iridium which will last 100,000 miles in a engine in good shape. Bill

 

[aahsac]

Crazy how long plugs last nowadays. I remember a decent 57 Chev with a 283, lucky if plugs lasted 8K miles.

 

[1965fastback]

Autolite 45's for me two, gotta gap em out more for Pertronix, so hopefully it will get rid of the slight cough in the engine.

 

[1965fastback]

Well I looked today and I have Autolite 46's gapped to .05or .055