Give me a quick refresher course. If I have a Sept 69 build date, what date code(s) should you expect to see on the block? and how would you determine if its a 70 or a 71 block?
Jason, I would look for a G or an H or J on front of the block. July or August or Sept. If I remember correctly there may be a 69 or 70 or 71 cast near the lifter galleys. I will have to look at my spare 70 block. Early 71 had the same casting number as 70. Very early 71 blocks had a small oil galley like non stage 70. 71 block with the big oil passage and 70 part number is the best bet. No one can tell it is 71 block when in car if VIN is milled off.
Jason, I way over thought this. Is there a two letter code and VIN stamped on the left side head mounting surface or a two letter code in the same place for a 71 but the VIN is on front where the power steering bracket attaches. This makes it quick and painless.
Jason, A 70 block date code is here.. I know you didn't ask, just an FYI for others that may have not seen the block ID sticky.. That code moved to the lifter valley in later years. Depending on which week of Sept 69, it should be an H or J. Technically, any casting date code simply must just precede the vehicle build date. Hard to build a car with an engine block that has not been cast yet, obviously. In practice, unless the engine was set aside for special handling or repair, they proceeded from the foundry, thru the engine factory, and into the vehicle in just a matter of a week or two, for a Flint Built car. All three facilities were located within spitting distance of each other in Flint back then. Since all 70 STG 1's were built in Flint, yours should follow this norm. I believe I have seen block date and vehicle manufacture codes were were just days apart.. but can't recall that exactly, to specifically use as an example. For identification of exact year, the two digit engine code, or stamped VIN number must be used. All 70 V8 engine codes start with "S" and in all years, the 3rd digit of the stamped VIN code will be the last digit of the year.. in your case, a "0". As Dave mentioned, the location of the VIN varied, you can see all the different locations here.. http://www.v8buick.com/showthread.php?214613-400-430-455-Block-ID-Prep-and-Oiling-mods Tell us what you find.. JW
Just looked at a November(69) 70 455 I have. It has L in the location Jim showed but behind where the water pump sits is a 70 code. This must be a year usage code as the block would have been for a 70(SF code). I cannot remember what the 71 blocks had here.
Jason, you have some good advice from others who have replied here, so I will only add that the date code on cast iron components will likely NOT be "G" on an early car. The example I currently have of a July dated block and heads (from the same 1970 Engine) are all coded G-10. The Flint code VIN and production code on this particular block are very high numbers, indicating July of 1970 rather than July of 1969. Both heads have "70" cast into one exhaust port. The earliest example I have an August 1969 code block and heads (from the same 1970 engine) are H-1 and H-8 coded heads on a on an H-9 coded block. The VIN and production code on this block are very low numbers. In fact the VIN indicates it was among the first 1700 cars off the Flint line for the 1970 model year. I am not certain when Flint began stamping the VIN on the front of the block, but I have a December code block (casting #1231738) that has a 1971 Flint VIN stamped on the front.
Jim, That is interesting info on the July date codes. I always wondered whether it was possible to have July cast codes for early built cars and another run for very late built cars. I would guess most likely not but the time frame to get parts cast for August built cars would be very short. I believe all 71's had the VIN in fron of the block.
I can not say definitively that overlap did not occur. Only that it is unlikely. Using the example in my previous post, the July dated parts being still fairly early in the month, leave three weeks of production in the 1970 model year. A good number of cars can be built in three weeks. I suspect casting continued into later weeks in July, but I personally have not been able to verify it through a comparison of date codes and VIN stamps on known original engines/components. As time goes on, this will be increasingly difficult. Unmolested examples are becoming few. It would be interesting to learn of examples dated near the very end of the model year, or at least later than July 10. Hopefully others will chime in. As an aside, there was a '70 GS455 here in Columbus many years ago that had the VIN stamped on the front of the block. I seem to remember it being a Flint build, but I could be wrong. Larry Gibson owned the car for a time, he would probably remember the details.
Jim, If you are referring to the gold 70GS455 that I owned for several years, that was a Fremont built car, with the VIN stamped on the front of the block as you stated. HTH Larry
Hypothetically speaking, lets say you had a car whose engine you questioned as being original to the car. All VIN stamps and codes are suspect. The only thing you can go by is the date code. Lets says the date code checks out to the extent that it falls in line with the build date of the car. How can you tell if its August 1970 or August 1971?
Jason, 1. First off for a 1970 big block Buick car............there were so many being built that ALL the major cast components should be only 1 to 2 weeks prior to the body build date................OR may even be from the same week as the body build date. Also all the major cast iron components will most likely only be a few days apart. (Block, Heads, Intake &, Exhaust manifolds) (I also know there are some exceptions to #1, but for your needs you should stick to this.) 2. Another thing you can check is which day of the week the date codes are for. If you check a particular date and it comes up as Sunday for 1970, but Tuesday for 1971..........then you have your answer. (You can reference my book for this.) 3. 71 motors were stamped on the front, so if you have no numbers there the motor would have needed decked on the front as well as on the head surfaces...........and 4. I think the 71 455 casting number changed sometime during the production year...................if that is true, depending on when that occurred a motor with the correct casting numbers would not be possible. Now this is for 1970 Production year cars only, so few were built in 71 & 72 that this will not hold true. Now if all that can't determine the validity of the engine...............then you are on your own unless you take it apart and look for piston part numbers etc. Duane
This is indeed correct. I have a copy of a GM bulletin (If I can remember where) that states a change in number that coincides with the enlargement of the main suction oil passage in the block. It gives a date, and a production code, that the change was scheduled to occur. I concur with Duane on point #3. Assuming the VIN was stamped on the front of all blocks beginning with 41H100001, then the VIN would have to have been obliterated by machining or some evidence of it would remain.
I have a 70-early 71 cast number block that was a non stage-1 and it has the large oil passage. It is In my GSX. It HAD a 71 vin on the front of the block. So I do not think the enlarged oil passage started with the new cast numbers. It is a March 71 cast block. The service bulletin states that the oil passage changed with build code 159. I have owned a June built 71 block and it had the 72 casting numbers on the back. So the casting number changed sometime between late March and June if that makes sense.
You are right Dave. I looked back through my bulletins, and found the same information. The bulletin made no reference to the casting number. I should refer to these bulletins before posting, I guess my memory is not as sharp as it once was. I'm glad I have these to refer to. I also stumbled across the bulletin referencing the installation of the Stage 1 oil pump spring in all 455 engines occurring at build code 136. The engineers were fully aware of the oiling issues with the 455, and obviously working constantly to correct them.
