HC pistons

[TulsaSpider]

I just received a new set of HC (4.5mm) pistons from one of our dealers. I inspected them and weighed them out as we have digital scales at my work. The difference in the pistons lowest 414.7 (two) 417.0 418.1 Three grams difference from lowest to highest. So am I right in saying they all need to weigh the same or is there something I don't know?

[mdrburchette]

Many manufacturers do not guarantee all the pistons will weigh the same, but I don't know how close they need to be.

[maytag]

They should be close, but if you really wanna get it right, you'll be weighing the small-end of your con-rod as well, and then match 'em all-up to get your "bob-weight" (piston weight + con-rod-small-end weight) close. To do this you need to build a fixture that will hold your large-end of the con-rod at equal height to your scale, and then weigh the small-ends.

But as to how much you want to worry about it, I s'pect that all comes down to how much time & money you're spending, and how far you're planning to go? When Fiat built this, I guarantee they didn't weigh them out.

[mdrburchette]

I sent all my stuff to the engine machine shop to get balanced. That way, everything was balanced together.

[fiatfactory]

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