I used a wafer wheel on a Dremel to carefully remove the punch marks so I could get the plugs out and again to clean them up, to get them back in. Once I was sure that they were seated, I expanded them with the hammer side of a ball peen (as klhanson stated), then used a center punch to peen over the edges in four spots.

Last edited by Phak1; 08/06/2021 7:51 PM.

Phil
Moderator, The Engine Shop, Interiors and Project Journals

1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube
Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes
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