Packard Forum Index » Pre-War (1899-1942)

Dear All,

John came over to day to help with measuring my cylinder taper. We found that the taper was from 0.001 to 0.003, depending upon cylinder and axis of measurement. So, my question is, does this seem OK to keep my original pistons, or do I need to bore things out and go oversize? It seems pretty good to me, but I thought I would check.

If I get to keep my original pistons, anybody have a set of rings, or know where I can get a set of rings? These pistons have 4 rings, not 3 as is currently standard.

Thanks,

Tom

If you're looking for just a serviceable engine repair and not a true rebuild, I don't think the 0.001-003 taper would be a problem, but of course you have to hone to get the new rings to seat. Just recognize that you won't have the fit that properly sized pistons and bore would give. As to rings, I wish I could be more specific, but those 4-ring sets are or were available not too long ago, why not Google "piston rings" and see what you get. I remember a parts depot, on the West Coast and perhaps the Pacific Northwest, that had them.

Owen,

Thanks for the info.

I realize the fit will not be perfect. I was just wondering if that was enough wear to cause major compression loss (given that I will have new rings).

I have sent an e-mail to a couple of vendors, but have not heard anything back. I was just wondering if anyone out there has a preferred/known vendor.

Thanks again for the help.

Regards,

Tom

Just had the engine in my 38 rebuilt, EGGE in L.A had all the parts .I've used them for several engines and they have always done a great job.
RT

If in fact you are going to use your old pistons (after a careful examination of course), you might want to review some of the older engine-rebuilding texts on piston reconditioning. Checking piston ring grooves for wear (especially the top ring) and recutting where needed is one item (the standard ring would then use a shim). You might also consider either knurling the piston skirts or using piston expanders to try to compensate for the extra clearance; while this is certainly less satisfactory than reboring and fitting new pistons, it was a common-enough practice years back.

I read about piston knurling in my 1932 Dykes. I am planning on measuring the ring grooves. A visual inspection of the cleaned pistons does not reveal any flaws. Do folks manga-flux pistons or do other types of inspection to look for hidden flaws?

Thanks,

Tom

Magnafluxing is only applicable to ferrous alloys but there are dye penetrant systems in wide use for aluminum alloys. If you're not familiar with their use, I'd recommend avoiding the risk of misinterpretation and having a professional do the test on your pistons and other aluminum parts in question.