Don't have pic to post yet, but I'm tearing down my 88 efi 460 and on the #4 and #8 cylinders there are what appear to be spark plug adapters. Oddly though, they are the same size and thread as the plug holes (the plugs will fit into the head and all 8 are the same). Are these just extenders? Are they stock? Never seen anything like it before except for adapters for different plugs. Crazy/lazy PO?

 

The gizmos are to delay oil-fouling the plugs in a worn out cyl.

 

heli-coils perhaps?
or plug indexers.

 

Ah, I see. Ok yeah that's got to be it. It burns alot of oil, which is why I'm pulling it. Crazy old farmer.

 

The extenders basically make any given sparkplug about 4 ranges hotter. Lets them keep firing even when getting drowned in oil. I used them on a small block chevy with a bad intake gasket (leaking at the cam galley) years ago. Hurt power/mileage a bit but kept the plugs from fouling every other day..

You doing a stock rebuild or something fun??

 

Depends on what I see when I get the heads off. One of 3 things: Swap in a used runner, stock-ish rebuild with a little oomph (within SD limits), or lose the EFI and build it.