Since around 1964 most small block Chevys have had two threaded holes at the rear of the block on the drivers side near the oil filter boss.These are to accommodate the clutch counter shaft for vehicles equipt with manual transmissions.Only one of the holes are required.Some vehicles used a counter shaft located approx 6" further to the rear,thus the need for the rear hole.Early blocks have only one hole and are pretty much worthless to a vehicle that require the rear hole for their clutch assemblies.īefore 63,small block Chevy engine used a "Road Draft Tube" to ventilate the crankcase.Featuring a large hole at the top rear of the block inside the lifter valley,these blocks are from the 50's through to the mid 60's.The PCV(positive crankcase ventilation system) replaced the daft tube in 1963.The vent hole disappeared in 68 when the system was redesigned to ventilate through the oil filler tube located at the front of the intake manifold.Later engine ventilated through the valve cover. The debut of the 283 in 1957 marked the end of the 265.Chevrolet went to an new motor mounting system placing the mounts near the freeze plugs on the side of the block.The old system had mounts located on the front of the block at either side of the timing cover. The very first small block Chevy,a 265 CID overhead valve v-8,did not even have a provision for an oil filter!The familiar oil filter boss on the small block came around in 56,along with an all new casting. While there were a pile of minor changes in the last 40 years to the small block Chevy,the basic design has remained the same for the years we are looking at on this site. The casting date can also be very helpful in identification.Found normally on the top or the right side of the same flange that mates to the transmission bell housing.(Behind & below the distributor).They can also be located on the right side of the block next to a freeze plug.You will either find an alpha-numeric date code cast right into the block between the image of two screws cast into the block,these are from the screws that held the date code plate while the block was being cast.This code I.D.s the month,day,and the year of the casting,note that this does not mean that the casting date was also the model year of the vehicle that rolled out of the factory with said engine. your small block Chevy is to use the casting number found on the drivers side rear of the block on the top flange that mates with the tranny bell housing.Numbers are raised approx 1/8 of an inch.The are about 3/4 of an inch tall.Even though you may have to scrap greese and dirt away,the numbers may be seen plainly while the engine is still in the car. The information found here will pretty much cover from 1955 -93.There will be more added as time and resources permit.īy far the fastest and easiest way to I.D. So it seems that the engine, trans and carb could all be from 68 or 69.Small Block Chevy Engine Block Casting Numbers Or I guess everything could be from 1968 and I could have a TH350 that came from a different donor car than the engine.Ĭan anyone glean any more information from the numbers? I'd really like to determine what what make/model/year of car served as the donor for this engine and transmission.Ģ839 = 283rd day of year, or October 10, 1969 If anything, I would expect the numbers to be the other way around - the engine casting code should be earlier than the VIN model year. I'm a little confused by the fact that the block casting number suffix of "HN" seems to state that the block was cast in 1989, while the VIN states that the car was some model of 1968 Chevy. The VIN Code 18F232087 seems to decode as: I have to admit I didn't think to look up the tranny numbers yesterday. The trans is definitely a TH350, so if the engine and trans were put in together from the same donor vehicle, then it looks like I might have the 1969 engine/transmission. 1969 350 350 4 bbl turbo 350 high performanceġ968 327 250 4 bbl powerglideIt looks like I've got either the first engine (1969, 300 hp) or the 3rd engine (1968, 250 HP).
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