Know this is a long shot, looking for 1 standard bore 455 HC piston with V notch part number 398666.


I have a broken one

 

 

I have one for you

 

I have 7

 

Pm sent

 

Pm back

 

You may want to check the deck of your engine block adjacent to the cylinder that the broken piston came out of. If you'll notice in post #4 above, the piston has a "B" stamped in it at about the 4 0'clock position. This was done on Olds engines to denote the "relative size" of the piston. Pistons were made in A, B, C and D to accommodate minor differences in the machining of the blocks. It's a good idea to match the letter on the piston to the one on the block.

 

Only stamp I found on it was a F

 

the stamp is visible in your second picture C

 

I’ll half to clean the top to make sure but I sure don’t see a C on my piston
can see a B on the other picture

 

Toronado being the flagship got the best of the best A bores containing A pistons....
W -30 & associated oai cars for racing lived a rougher life at higher temps & extra clearance of a size smaller piston than bore designation was SOP.

I would be shocked if I did not have piston you reqire in Lansing Michigan



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Ok I’ve cleaned the tops of 3 pistons and there is no stamp on the top the only stamp I have is the F for the front , part number and the GM date code

second pic is a different piston

 

So which pistons were larger to smaller ?

 

the C is clearly visible at the bottom of the picture 45 degrees from the notch on the outside of the piston not in the dished area and I can still see it faintly after being cleaned ,it is still there

 

If the tops of all of your pistons look like the ones that you have posted I would seriously consider a replacement set. They appear to have suffered from detonation. Can you post a pic of the broken area on the first piston? If it came out of the engine with pieces missing between the ring lands, then you definitely have a problem. Factory high compression pistons weren't made to run with today's low octane gasoline and have a tendency to self destruct.

 

there was a detonation problem

im putting this motor back together so I can drive my car
I’m building a 462 forge piston roller motor but want to drive the car in the mean time

the ring land was cracked and I dropped the piston and broke the side out

 

The good thing is with replacement (read thicker) head gaskets, your compression ratio will drop to a more tolerable level. Good Luck with your project.

 

Got a piston coming thank you

My question I’m staring at this piston I can not see a C on this piston , I’ve zoomed in on the picture

I can not see It

 

Hey all,
Wanted to jump in here as I am looking for the same piston but when I tore down the engine I had 1 that was an aftermarket.
My number 3 piston clearly shows a C, but this is for the #5 cylinder.

Any help would be greatly appreciated.

 

The letter designation, from the factory, is stamped in the deck surface of the block adjacent to each cylinder.

 

I found a CC between 1&3 a CC between 3&5 and a B between 5&7.
how do I interpret that?

Thanks

 

See this thread: Stamp on the block deck

 

I found the one for #1 with you help. My block is still stamped CC not just a single C.

Added pic. So I would need a C piston then.

 

Learn something new everyday. #5 is the aftermarket piston, I will try and pull the part number from it and measure the cylinders.

Thanks for the help