Rummaging around in the stuff left in the old garage at my house in LA, I ran across a box marked, “303 Olds blower pistons”. They came with a stash of early Olds stuff that I got years ago. They are used but in good shape, put away dirty. They do have a number on the top. L2074, and some other chicken scratches. They have what appear to be heavy duty pins and the top rings look like chrome rings. I don’t have anything to accurately measure with but they appear to be 3.85 in diameter. My Googling didn’t find anything that looked right.
Decades ago, all TRW pistons had L in the part number. From the bottom, it does appear to be a forging. I have old catalogs that list the 303 as 3.75 bore and the 324 as 3.875. There is no piston listing in either of them.
Thanks for looking. I’m going to clean them up and list them for sale. I was just hoping someone with old catalogs might find a listing. At 3.850, they would be for a 0.100” over 303, strange. You’d think they would go 0.125 over and use 324 pistons. Oh well. I’ll clean them up and inspect them then send them down the road.
Bob, I had a very early set of TRW’s in a 301 that I built, seems like I bought them 1966. They were 12 1/2 to 1 but what was really unique about them was the crown was fully machined, crown, dome and valve notches. In appearance they looked a lot like the forging your Olds pistons have, but on my TRW’s there were three, or maybe two?, ribs inside the slipper skirt as seen in this marked photo. I’m not suggesting your pistons are TRW’s but could some other manufacturer have used the same forged blanks? To clarify, here’s a forged crown typical of the later TRW’s.
I noticed the lack of the ribs on the skirts too. But they are full skirts as compared to a real modern race piston. They are also very light and top heavy. Just some interesting old parts. Hopefully none of them are damaged, they might be useful to someone.
From what I recall, weren't the skirt ribs a later upgrade after TRW found some engine applications had problems with skirt tab breakage and so some designs got upgraded?? It was a problem for the first couple years of SBC LT-1 350 OEM forged pistons that Chevy originally spec'd TRW to make. TRW added the skirt ribs on the aftermarket replacement versions and made the production change on OEM's as well. Other engines may have never needed them.
Those are some old TRW Power Forged stock relacement pistons. My old catalogs do not go back that far however I did find that number listed in the spec. chart but it does not specify the application, only the clearance specs. Here is what I have: L2074, power forged, max available o.s. +.060, 3.875 bore, cam J, skirt clearance: .0025 top, .002 bottom. Ok, hope this helps, take care, G.....
Hey, Bob; Very possible those pistons were made prior to the 324 coming out, since the 303 was out for a few years prior to the 324. Or other reasons not to go .125 over. Marcus...
For "odd-sized" rings, look at the metric stuff. Sometimes there's crossover, if the ring thickness n type are acceptable. Marcus...
I cleaned up a few of them and then forgot to throw them in the family truckster when leaving LA. So they’ll be sitting on the workbench until I get back down there.
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