That casting number was used on most truck 350s from 1969 to 1979. The casting date looks like 8 to me, meaning 1978, and the suffix code date on trucks online isn't complete, so I'd guess it's from 78, also due to the shape of the stamped characters. But it doesn't really matter, a 1973 and 1978truck 350 are about the same engine. 4 bolt mains, cast crank and pistons, 1.94/1.50 valves, low compression, Quadrajet, etc. The engine was not originally in a 74 truck, they did get swapped around a lot.
What do these #’s tell us? Supposedly from a 76 Chevy truck. Do the numbers tell if it’s a 4 bolt main engine?
TYZ could be a 1975 Chevy pickup truck engine. The 3970010 casting number usually is a 4 bolt main engine, and 4bbl truck engines that have it are almost all 4 bolt mains. You can be sure by pulling off the oil pan and looking. only the center 3 main caps have 4 bolts, though
My vette engine is back in a truck now. Gained a good bit of HP from it’s time in a vette. I got one of the quickest 61 C40s in the country.
Chevy made millions of those truck engines...and people hold on to trucks for a long time. Not surprising the engines end up everywhere.
My 3970010 block was a 2-bolt main. Decoding the numbers by the passenger side head revealed that it was from a '74 police car.
Seems there were some 010 blocks used in passenger cars that got 2 bolt mains, but most of the 2 bolt 350s were 014 block castings. I haven't seen a 2 bolt 010 myself, but I've only looked at a few dozen of them in my life.
The extra two bolts on the mains add at least 100hp. I had my 4 bolt main bolts oversized. Added at least 150 hp.
the partial VIN is 1976. Assembled August 11th, I guess it was one of the first 76 engines. Norwalk assembled X and F body cars, didn't they?
So, not a truck engine but a Nova or Camaro engine? the suffix code is confusing then as they say 72, 73 or 77... I guess it is a corvette engine now that it is in a corvette!!!
The suffix codes...there were lots of them, and the records of what went into what, aren't perfect. Truck engine suffixes from the 70s mostly started with T, and the partial VIN started with C. 1 was used for Chevy cars for the VIN.
The actual 4 bolt castings could have been machined for 2 bolt caps. The casting marks designate the original intention. SBC 2 bolt casting and 4 bolt castings are two entirely different animals. The 2 bolt block has heavier webbing and different casting numbers. Did they machine 4 bolt blocks for 2 bolt caps? They certainly could have but that would make them prime for failure as a hot rod motor. The reason that a 4 bolt block could get away with lighter webbing is because the 4 bolt caps make up for it. There are ways to cure the problem of lighter webbing and 2 bolt caps but as common as SBC blocks are there is no reason to bother with them. Most smog era truck motors were 4 bolt, at least in my experience they are.
I bought one from a scrap yard once out of a GMC pickup and not only was it a 010 4 bolt block, it also had a steel crank and the beefier X rods.... And yes, it was a 4-bbl carb motor..
The Jalopy Journal
