Joe: The pictures above are of my '52, not Hank's '46. Mine is domed pistons and the 477 head.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/13 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
I have 2 4819 heads in my garage. Not sure of the years but casting numbers are in different locations. They both look the same possibly a very small dome piston? Not sure. Can we see pics of what you have on your engine?
1947.2 GMC 1/2T panel 1947.2 GMC 1/2T long bed 1948 GMC 1/2T pick-up
Too bad Patrick Dykes in no longer alive. He was a GMC guru and his old catalogs had a detailed discussion of the GMC 6’s, their blocks and heads. Sadly I threw mine out a few years ago when we were packing up to move. Maybe someone has a scan of one.
The 477 and the 412 are for domed pistons that were used up until 1953. The flat piston uses the 819 head. If you have an 819 head on your engine, it is not original. The 819 head was not produced until 1953. The pistons you picture are not OEM. Your engine originally had Zollner pistons and probably a 477 head. It looks like someone used some 1953 aftermarket high compression pistons with a 1953 or later head. I haven't seen OEM 228 1952 and older pistons for sale in a long time. However the old Zollner pistons ran forever. I would scrap the engine you have and start all over. 228 engines that will still hone standard are around. It looks like your block has been bored to the max anyway. Any way you look at it parts are going to be difficult, Some of the dome piston heads had 30° valves and some had 45°valves. Either will run with the OEM domed pistons. Do you want to keep your vehicle original or do you just want it to run?
Here is a photo of a NOS 819 head. It has oblong combustion chambers. The 419 and 412 have a large round combustion chamber like is pictured in Bill Hanlon's photo. A quick glance at the combustion chamber will tell you if you have an early head with domed pistons or a later head with flat pistons.
OK,guys, first of all, thank you all for your input. If I interpret the postings correctly, the 819 head I had on my truck was not original to the 1946 model year, nor were domed pistons. Furthermore, the pics I sent of the domed pistons which are in my motor are not OEM. Okay, I get that part, however "gmc-is-me" responded that my pistons were custom for the 819 head, while "crenwelge" replied the 819 head uses flat pistons. I'm totally confused. I had domed pistons in a 819 head, on a 228 ci engine, which until recently ran fine. As I go forward, do I search out 477 or 412 heads to accommodate the existing domed pistons, or do I search out flat topped pistons which are compatible with a 819 head ?
If you want to stay with the 228 engine, I'd suggest finding another complete engine to rebuild. With the amount of damage that piston is showing, it's very likely that the block, the head, or probably both will have some cracks in them you haven't discovered yet. Finding one obsolete custom piston to replace the damaged one is about as likely as finding a chicken with lips. These old engines are tough, but they're not bulletproof. Most people in your situation would probably look for a 248 or 270- - - -they're both bolt-in swaps and are more plentiful, and more powerful than the 228. Send me a PM- - - -I might have what you probably should be looking for. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Engines with he 819 head came from the factory with flat pistons. However aftermarket pistons with a dome were offered through the years to raise compression ratio. The factory domed pistons that came in an engine with a 477 or 412 head will not work with an 819 head. The dome will actually hit he head. The aftermarket domed pistons for the 819 head raised the compression ratio considerably. The higher compression ratios usually required the use of high octane gasoline.
Above is a link to what a factory domed Zollner piston would have looked like that came in our engine from the factory. It would hit he head on a 477 or 417 engine. What you have is aftermarket high compression pistons. Running gasoline with too low octane may have contributed to your failure.
