<VV> Spark plugz

[Jim Burkhard]

Lest anybody be confused the so-called "proper" (or at least 
originally intended) Corvair plug is the FF series, not the 
F series. The FF plugs have been scarce for so long that 
people seem to forget what is the original plug.  But unless 
you have a key to my garage (which has a big box of them), 
you can't find FF plugs, so people use the F series plugs as 
substitutes. It is indeed threaded short.

You can generally get away with this, but it could 
conceivably cause problems if you run F series plugs for a 
while and then try switching to a full-threaded plug like an 
FF, FFS (Jim Davis explains the FFS well), or somebody 
else's with similar shell geometry.  In that case, you 
should run a thread chaser *before* the new plugs down 
through the holes before switching to clear the "dam" of 
accumulated carbon.

Jim Burkhard

Padgett wrote:

> The odd thing about the Corvair plug (the "F") is the 1/2" reach (length 
> of threads). "FF" were threaded all the way down the body, "F" plugs 
> stop one thread short. No suffix letter means a 3/8" reach plug and a 
> 44S has the electrode in almost the same place as a 44F but a lot less 
> threads and the plug body is shorter so there would be a cavity in the 
> head at the plug to collect carbon.