TRW Piston I.D. Help, L2376 can anyone Help ??

Ron Miller · Post by **Ron Miller** » Sat Nov 26, 2005 5:38 pm

I have a chance to buy this piston set dirt cheap and would like to know what its for. The guy thinks their for a Chevy sbc 400, but he's not sure. The piston number is L2373.030, its forged and ???. The guy that has the pistons lives out of town from me, so I can not view them for my self. He measured them with a diameter of 4.155 using a ruler x@**!!. He dose not have a close way to measure the compression distance either. Anybody out their have a old TRW catalog or used this piston before. I've looked in current catalogs and even tried looking at some sites on the net, but had no luck identifying this piston.

Thanks for looking

Ron Miller

bill jones · Post by **bill jones** » Sat Nov 26, 2005 5:46 pm

-you have two different numbers listed but the 2376 should be a fairly heavy 400 SBC with a deep dish (seems like it's about 24cc dish) and a 1.565" or so pin height where you'd use a 3-3/4" stroke and the 5.565" stock 400 rods.
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-I can look up some numbers on some old balance cards but usually we cut those pistons .135" and used 5.7 rods with them for stock type street engines.
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-If you are asking about a 2373 piston I have no idea.

Ron Miller · Post by **Ron Miller** » Sat Nov 26, 2005 7:34 pm

Hi Bill,
Thanks for the quick reply, and I should of caught my mistake. The number is L 2376, not L2373. Thanks for catching that. That is what I was hoping too hear, for a 400 sbc. Thanks for the idea about cutting the piston tops .135 and using a 5.7 rod. I'm sure this will take alot of weight off the piston. I would to build a low budget 400 with that piston. From memory, do how much material is left in the valve pocket area and the tops ? I'm thinking of using a solid lifter cam with .560 lift and a vortec head.

Thanks Again Bill

Ron Miller
Brownstown,Mi

SupStk · Post by **SupStk** » Fri Dec 02, 2005 1:02 pm

Ron,
i was waiting for someone else to chime in. I have used a similar piston (L2352F) for low dollar 400 SBC built ups. This piston has a 12cc dish about .085 deep, after milling .135 it would become a flat top. There is material enough to cut valve pockets, if i recall correctly it's almost .400 thick. The top ring is about .115 down after cutting. I've had several detonation related failures of the top ring land using this modification.

crazycuda · Post by **crazycuda** » Fri Dec 02, 2005 2:37 pm

I also have a set of L 2376 400 pistons. I have also been planning on cutting the tops down to a flat top and trying to run the 5.7 rod. If anyone else can chime in It would be greatly appreciated.

bill jones · Post by **bill jones** » Fri Dec 02, 2005 3:57 pm

-I have used the 2352 and the 2376 pistons both cut .135" and some cut .155" for use on undecked blocks----probably done over 30 sets for street and oval track modifieds.
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-The only failures were a set of 2352's that I cut .135" and then I cut a "D" shaped dish besides that---and I machined the dish too close to the back side of the top ring and broke the intake valve side of the top ring land for about an inch on several pistons.
-These were used in a 78 Chevy pickup truck for about a year and a half and the truck averaged about 80,000 miles a year.
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-The other failures happened to a set of 2352's that I got greedy on and I had butchered the insides and along the sides of the pressed in pins to get the weight down to 503 grams.
-These were also dished about .080" deep but I cut the valve notches deeper than usual and connected the intake notch to the exhaust notch with a trough in an attempt to get the dish volume where I wanted it.
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-I used these in my 67 El Camino for about 10 years and 28,000 miles in conjunction with a set of 87 Vortec swirl vane heads.
-I had ported the heads pretty good and I wanted to see how the swirl vane acted on a carbureted engine.
-Those heads and the compression ratio at 9.77:1 at 4200 elevation didn't really like each other and the max ignition timing tolerance was 27 degrees yet it wanted 17 degrees at idle and the vacuum advance was also pretty fussy.
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-So I knew all this and I tuned it by the sound of the ping----which was only 2 degrees away from major hammer----meaning this engine rattled terrible bad if you gave it 2 degrees too much timing any where.
-But even then I drove it for 10 years---then I sold the engine to a kid and showed him how good the engine ran and how docile it was yet still capable of running low 13 second 1/4 mile times on stock street tires muffled, emission legal etc.
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-This kid drove it 3 months and the pistons were ALL broken----right thru the bottom of the valve notch trough---down both sides to the ends of the oil ring slot on the valve notch side of the pistons.
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-The only thing I would do different is I would now lightly shotpeen the areas that I had machined and I'd leave about 4 grams more metal under the valve notch trough and maybe figure out another way to drop the CR
about 3/10 of one point---or run a little race fuel.

Ron Miller · Post by **Ron Miller** » Sat Dec 03, 2005 11:55 am

I would like too Thank All that replied on identifying the TRW piston for me, I learned something new. Thanks Again Bill, SupStk.

Ron Miller