[chiphead]

I could use some help ID-ing the heads on the 400 in the LeMans I just bought. The PO ground all the casting numbers off so I can't run the numbers. It's got screw-in studs and all the exhaust flange bosses are threaded. The engine pumped 150 PSI with a Crane 284 cam (228/236/114) installed. The block is a 68 or '69 WZ code 400.

What do the sparkplug holes look like on the 71-later taper-seat heads? Right now I've got gasket seat plugs in it. But the sparkplug gaskets come out sort of tapered-shape when I remove the plugs.

How many accy bolt holes does a 71-later head have in the front?

I suspect the heads are 16 or 62s but need to confirm so I know compression and plugs to use. Thanks!

[Half-Inch Stud]

Sure sounds like 16-12-13-48 but maybe 64. Possibly 5C-4X-6X small chamber. R44S-R45S vs peanut plugs

Look for a generous counterbore that accommodates a 3/4" socket, and flat seal washer.
Peanut heads don't accomodate the R44-R45 plug. But the older heads will fit the peanut plugs.

[25stevem]

Here's some guide help for you.

In 1972 all V8 heads where cast with 1/2" pipe thread hole in the exh side of the heads in between one end Exh port and the center Exh ports.
This was where the temp sender was moved to from the Intake Manifold water crossover passage to this new 1/2" pipe side hole.

By the way even though it may not look the best to folks eyes, this new hole is a far more accurate place to judge your motors water temp from .

Even though the early heads will accept the later peanut 5/8" plugs there is not much of a 45 degree taper there to seat them well on.