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Type IV Beetle In The Works: Pistons

Hello all.

I've gotten back to working on my engine project again. The 96mm "AA" pistons/cylinders and Totalseal rings are present and accounted for. I'm glad I took the rings off and looked at them before installation, because one of the pistons was missing one of the oil control rings (the flat ones). Rather sloppy of them. On the bright side they weight out nicely, between 432g and 425g. I'm going through the trouble of balancing them down to 1g (the precision of my scale).

On that subject, where should I remove the metal? There is no obvious place on the undersides from which to work. I'm thinking I'll begin with a light polishing of the valve relief pockets on the topside, then remove any odd casting blobs on the undersides of the heavy ones, and see where my weights are at then.

I think the valve relief pockets should be polished because they have a rough as-cast finish that looks like it will collect carbon as well as sharp edges that might promote detonation. Am I on the right track or should I leave them alone? I'll make sure they cc out the same when I'm done.

Any opinions here would be great.

Thanks, Harry

Reply to
Harry Smith
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Nicely? You must be joking? :)

Was that bare pistons, nothing on them like rings or pins?

Over 10g weight difference is TOTALLY UNACCEPTABLE. I would dare say you can't safely remove that much weight (aluminum!).

I would send them back and demand a matching set of 4. Or if they can't deliver, shop elsewhere.

Mahle pistons come within 1-2g right out of the box....

Jan

Reply to
Jan

Okay, a big typo there can explain this... The actual weights were

432, 433.5, 434, and 435g. That's bear pistons, no rings or pins. What was indeed "totally unacceptable" was that one of the pistons was an oil-control ring short of a full set. Fortunately I've got the Totalseal rings so I'm not even using that set, I just wonder how long that piston would have lasted. It was one of the flat (non wavy) rings, thus easy to overlook.

Any opinions about the surface of the piston? Unless I learn otherwise I'm going to smooth out the valve relief pockets, then see about the balancing.

Thanks, Harry

Reply to
Harry Smith

Pistons usually have cast bosses on the inside that you can safely remove some material from. Also, you can remove material from the wrist pin, it's steel and you would need to remove less material for the weight you need.... and it sits right in the middle of the piston. You can drill or grind the wrist pin larger on the inside, it would be best if you could grind the ends into a cone shape, same amount of material removed from each end. The middle section would then remain untouched.

Jan

Reply to
Jan

Hi Jan,

Can't he balance rod + piston + pin combo? IE try to match heavy piston with lighter rod. After all they should be all balanced together in the end.

Anton

Reply to
anton

I would not recommend it, because the weight center of the whole combination may shift, and even if the overall weights are the same, the balance across the 4 rod/piston assemblies is lost.

Balance pistons to match each other, and balance the rods to match each other. The rods being as long as they are, their weight centers should also be about the same. So, balance the rod caps to match each other, and then ba;ance the main rods to each other, and THEIR weight centers to about the same spot on the rod......

That is, if you want to do it right.... :D

Jan

Reply to
Jan

Hi Jan,

Makes sense...

Thanks, Anton

Reply to
anton

How do you like the pistons? I am considering a set for my 77 Westie rebuild and would like some opinions.

I guess they are cast, and not forged? How did the balancing go. I guess i'll have to do the same if i go with AA 96mm.

newbie here, am trying to gather as much info as i get into this as possible.

thanks dp

Reply to
dweller

okay, just got my set of 96mm AA p/c's. I'll have my mechanic check the rings for any missing. And the balancing. Am curious where you found the Total Seal rings you are going to use, and the price?

i might consider them, esp. if i'm missing any rings ... am checking one p/c now and don't see the retaining clips supposedly provided ...yet.

dp

Reply to
dweller

On Jun 5, 8:25 pm, dweller wrote: > okay, just got my set of 96mm AA p/c's. I'll have my mechanic check

The clips were all in one big bag. I got the rings through Jegs. Talked to the Totalseal company to get the part number (T 7255), but they don't like selling to the general public so you have to go through someone like Jegs. The price actually varied widely based on who I talked, I think I paid about $120 with shipping. Good luck with yours. I still don't actually have my together and running, so I can't really speak to the quality of any of these parts.

Harry

Reply to
Harry Smith

On Jun 5, 8:25 pm, dweller wrote: > okay, just got my set of 96mm AA p/c's. I'll have my mechanic check

The clips were all in one big bag. I got the rings through Jegs. Talked to the Totalseal company to get the part number (T 7255), but they don't like selling to the general public so you have to go through someone like Jegs. The price actually varied widely based on who I talked, I think I paid about $120 with shipping. Good luck with yours. I still don't actually have my together and running, so I can't really speak to the quality of any of these parts.

Harry

Reply to
Harry Smith

Hi Harry, i gave my pistons to the rebuilder/mechanic the other day, got him to look them over. He didn't want to look at the rings yet to see if any were missing, said he'd look when he was ready to install...i kinda hoping he might take the time to balance them, or at least check the weight (i have no scale), so will have to pester him to check them out. I plan to be around for most of the rebuild if possible (scheduled late this week, as the last parts arrive). On the brighter note, he said the p/c's appear to be forged. Is that your assumption also, or did you know beforhand? The supplier i bought them from never said.

How's your rebuild going?

dp

Reply to
dweller

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