Re: 186 heads: 1.5 with hardended valve seats to 1.6?
Recommend leaving the exhaust's "as-is", the 1.500's with the seats.
You won't know the difference with the 1.600's.
Put the 2.020's in and be happy!
Thanks, Gary in N.Y.
P.S. You COULD (and most likely will) end up with some "junk"! Not worth the risks. We do these almost weekly on exhaust seats. We have both, special inserts (custom made) AND special blades with some 3/32" radii on both. This lowers/eliminates the risk of "hitting water"!