Piston ding

[RichV]

I removed and cleaned the pistons I plan to use in the target bike. They all look great but one has a ding on the ridge. I probably did it when I removed the engine. So I have two questions:

1. Should I use it (file it down) or replace it with on of the other pistons I have with the same numbers stamped on it? Oddly, someone wrote the number "95" on the top of each piston. The same number is written on the four from the other bike in what appears to be the same handwriting. Do I need to keep the ring set with the matched cylinder if I swap out the piston?

2. The manual tells you to check for "wobble" in the piston pin. It's very small but there. Any idea what the tolerances are for this? The manual doesn't really tell.

Here are some photos of the ding for your viewing enjoyment:

[BA80]

Smooth it off and it should be fine.

Be more careful.

[trbig]

Agree with Greg on the ding. A wobble though.. where the pin can move up and down in the piston hole would lead me to believe it would make a knock in the motor while running? Maybe others can chime in since I've been wrong many times before.

On the other stuff, I've seen pistons that I thought were from factory that had writing on them as well, and no idea what they were from either. My only guess is that each piston was weighed and matched up with 3 others the same weight before assembly since I imagine cast can vary slightly.

I will caution you on re-installing used rings. Since they've been heat cycled, they'll be extremely brittle and are easily snapped.

[RichV]

Do you know a reasonably priced source for new rings?

If I replace the rings should I deglaze the cylinders?

Thanks again for the advice.

[TADracer]

Smooth it and use it!

But if you are interested in wrist pin measurements here are mine from when my motor had 35,500 miles on it.

All numbers are Cylinders #1, #2, #3, #4
Connecting rod diameter (pin end)
.6525” .65195” .65195” .6520”
Wrist pin diameter
.6519” .6519” .6519” .6519”
W/P Fit Clearance .001” .0005” .0005” .001”

These make for no wobble on the conn. rod.

[RichV]

Here's the repair I did. Filed it lightly and sanded.

Does it look okay now?

[rover]

rings

Do you know a reasonably priced source for new rings?


I just saw a set of std size rings on a web site, I think it was cheapcycleparts.com The ad was on the buick forum site. I will look later, and if I find it, post the location and the price.

[rover]

rings

Yes, cheap cycle parts.com. I googled it, and it was the top one on the page. The price is $46.61, I'm thinking that is for one piston, that would be $186.44 for four pistons. I'm not familiar with the modern prices, but that seems a bit high to me, but I haven't bought this type of parts for about 20 years. Hope this helps.

[rover]

rings

Yes, cheap cycle parts.com. I googled it, and it was the top one on the page. The price is $46.61, I'm thinking that is for one piston, that would be $186.44 for four pistons. I'm not familiar with the modern prices, but that seems a bit high to me, but I haven't bought this type of parts for about 20 years. Hope this helps.

[GLoweVA]

If i remember correctly, i paid about $50 for a set of 4 off ebay 2 years ago.