198 versus 215 pistons, 1962, 1963 Specials

[Pete Phillips]

Does anyone know if the 198 V-6 pistons are interchangeable with the 215 V-8 pistons in the compact Buicks? I suspect they are not. The 198 pistons are just about impossible to find.

[Frank DuVal]

According to that new highly accurate database, aka Wikipedia  , you would have better luck with 264 cu in pistons. Why?

 

Bore and stroke:

198      3.625  x  3.1875

215      3.5  x  2.8

225      3.75  x  3.4  

264      3.625   x   3.2

 

Now I have no idea if the pin diameter or height to top of piston, shape, etc are the same for 264 and 198 pistons. But, 215 and 198 are a definite no go. 

Edited January 21, 2018 by Frank DuVal
Had numbers transposed. (see edit history)

[NTX5467]

Aside from the items mentioned, WEIGHT is another key thing to be concerned about.  That affects the engine's "balance" situation.  The compression height can relate to how tall the piston is, but ALSO the skirt length and configuration (which relates to crankshaft counterweight clearance).

 

NTX5467

[nerdymonkey1010]

ive been wearing myself out as well trying to research this for weeks.

the 198 is 3.625" bore by 3.200" stroke. it has a 1.850" compression height and a .875" pin.

the 215 bore is too small. only 3.500" 

the 264 as mentioned above will not work because it has a huge dome piston with a 2.25" compression distance.

so far the closest I can find is a Ford 223cid inline 6. 1.84"CH 3.66" bore, but the pin diameter is .905" which would require boring out the connecting rods

 

Frank, your numbers are mixed up. the 215 and 225 are swapped

 

Edited January 19, 2018 by nerdymonkey1010 (see edit history)

[Beemon]

Might be easier to spin a 264 piston in a lathe to cut the dome off than to hack up some connecting rods. I do not know if you can get from 2.25" to 1.850" easily, but couldn't hurt to try before permanently altering your also very rare connecting rods.

[NTX5467]

How much you can cut the dome will depend upon the shape of the underside of the piston crown area.  It's probably NOT flat, but the contours basically match what's on the top side.  Which means "not a good idea" as a thin spot would result at the peak of the dome.

 

NTX5467

[Frank DuVal]

Woops, I have the corrected numbers in my post now.