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Thanks for the information

Quote:

Do you know if skirt expanders are still available for a 327? TIA 53 Cavalier

Has anyone had piston slap and known how much "extra" clearance it took to cause it? I'm pretty sure I'm dealing with piston slap on #4.

I was talking to an older mechanic (opened his shop in 1967) and he said piston slap could start to develop around .005"-.006", and he was referring to a normal piston, not a pre-exapanded Packard Thermostrut piston.

What I'm getting at is, that if piston slap on a normal piston can show up around .005"-.006", and the typical clearance should be around .002 to allow for expansion, then piston slap for a Packard with Thermostrut pistons could show up at maybe .004" as the clearance for them is only .0005".

Obviously Thermostrut pistons, that only have .0005" clearance, expand very very little when they are warm compared to a more typical piston.

Thoughts???

.0005 must be an error. I dont think you could fit any piston that tightly. Read the Packard manual very carefully.

If your noise is indeed piston sap in one cylinder, then replacing that piston & ring set with a new one identical to the others should eliminate it. That would involve removing the oil pan and the head, and measuring the bore to be sure it is in reasonable shape, which it probably is. Piston clearance and ring gap should be at least what Packard recommended. Check ring gap about halfway down the bore.

If you can't obtain one new piston & ring set that is identical to the others, I'd get a full set of new pistons & rings. (All 8 bores would need to be checked carefully for size and for any excessive wear, and light honing would be necessary, whether replacing one piston or all of them.

An engine with significant wear might require ridge reaming prior to removing any piston.

If the pistion slap is minor and transient, it might be best to tolerate it if the engine has high mileage and no other issues.