Help ID these spark plugs
 

Inherited a set of these spark plugs; they fit a Model A head but I don't have any information to confirm they are the proper plugs to use for it. Anyone know if they would be OK to run in a Model A? Any help in identifying would be appreciated.

Re: Help ID these spark plugs
 

...guess a photo would help! :)

Re: Help ID these spark plugs
 

They were sold for the model A and others a few years back.

Re: Help ID these spark plugs
 

I have a set in my car right now. Aside from being one piece they are identical to the last version of the C-4. They are a little too cool and may soot up with too much low speed driving.

Re: Help ID these spark plugs
 

I used C16C in Coupe from 1962 to 1967, 40,000 miles. they work best at highway speeds.

During this time I was driving 50 miles round trip 7 days a week (from 8000 feet to 5200) at 45 to 55 MPH to and from town.

Not so good after I moved into town with short trips, stop and go they foul out.

In 1979 or so Champion changed them to W16Y.

The recent number is Champion #561

Champion W-18s work well in town with short trips as long as you drive a little at 45 to 55 every now and then. Again many short trips with no highway and the center electrodes tend to collect carbon.

Again a little driving at 45 to 55 cleans the center electrodes right up. The outside steel ring of plug will have some black carbon which is OK as long as center electrode is tan colored.

If you idle alot and do short trips they will foul.

Re: Help ID these spark plugs
 

That's exactly the information I needed. Thanks to all who replied.