Hi all,
I just went through a comparison exercise with a sandcast owner on this topic. I know its one which has been touched on in the past but I was just wondering if any conclusion was made about engine sequence numbers (i.e. the two matching numbers stamped at the back of the cases, near the front sprocket)?
It has in the past been suggested/concluded (Im not sure which) that these were stamped when the engine cases had been machined as a pair. If this is the case, machining the cases would have been one of the first steps in the final production and assembly of an engine, the end product combining the sum of individual parts. There are many parts in an engine which have been noted to have (likely varying but mostly similar) date codes stamped on them. But machining the cases could have been the first step for Honda in assembling a group of earlier completed, dated parts into a completed engine.
The casting dates of one pair of cases in my comparison differ, to me indicating that casting dates alone are not an accurate representation of engine production sequence. As with many parts, they were cast etc then lay in wait until it came time to machine and assemble them. The stamped sequence numbers would have been applied at a later date to the casting date and these numbers are present, and are matched pairs, on both sets of cases being compared. This shows that each engine has cases which were machined together as pairs.
So the information collected was:
Engine 1:
Case Seq Nos: 782
Oil Pump No: 596
Casting date 4.7 Top / 4.11 Bottom
Engine 2:
Case Seq nos: 813
Oil Pump No: 857
Casting date 4.11 top / bottom unknown
So in comparing the sequence numbers (and assuming of course the numbers on the cases were stamped in consecutive order), you could conclude that Engine 1 cases would have been machined earlier than Engine 2, by 31 sets of cases. The latest casting date present on the halves of the engines is 4.11, similar between both engines. The sequence numbers suggest a very close machining date for both sets. However Engine 1 is evin# 4xx, Engine 2 is evin#1xx.
Further oddities occur. Its been noted that the first sandcast cases were cast without oil filter locating ribs, and without casting dates. I have seen this up to circa evin#250. Steve S noted that his evin#254 has the locating ribs and casting dates. So this range should be roughly the evin# crossover between the engine castings being revised. The comparison Engine 2 with evin#1xx has the revised engine casings with a 4.11 casting date and locating ribs. This supports the argument that the cast date on the cases bears no relevance to the evin# of the engine.
I found this exercise interesting. Im sure there would have been a core group of engines passing QC without requiring revision, then stamped with evin#'s more closely tied to the production date. However this particular comparison shows that two engines have been assembled within a short period of each other, but one engine has been assigned an earlier evin# (to perhaps replace the original engine which didn't pass QC). Again, this is assuming each machined set of cases are stamped with the next consecutive number.
It has in my particular case explained a large frame VIN / engine VIN mismatch in the frame containing Engine 2. The sequence number of Engine 2 is a more reliable indication of a factory matched frame and engine pair which could be doubted if you only considered the stamped evin# and frame vin#'s alone.
This is why Im curious if there was a conclusion about the sequence numbers.
Regards, Steven.
