Sorry to bug youts again... but I'm still trying to get some info on this block in my 73 Vette. I contacted Mortec and they were more than helpful on the ident. It turns out that the casting number, date and CWM suffix codes ( both head and block) are all correct for my 454 4 spd. It was cast 11/1/72, built 11/3/72 towards the beginning of the run of the 73 year. Now it seems as though the excuse of 'they just ran out' does not fit. I'm just trying to find out if anyone else ever came across an origional to the car 4bolt LS4 before. I still have to drop the tank to read the sticker... maybe that will tell me something... but until then I've got to get as much out of this internet thing as I can.
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Re: 73 LS4 4bolt ...again...
Greg-----
I seriously doubt that the tank sticker is going to tell you anything about engine block main bearing cap configuration.
For most big blocks, any block casting could have been manufactured into a 2 bolt main configuration or a 4 bolt main configuration. A 2 bolt can also be converted to 4 bolt very easily and it would be impossible to tell if it was original or done later.
In this case, there's absolutely no way to tell how it happened---it could have been either. Basically, I consider the issue irrelevent. If you were able to find out that it came this way originally, so what?In Appreciation of John Hinckley -
Addendum
Also, if the engine has fittings above the oil filter which are drilled and tapped (and, appear to have been originally so), that would be a lot more evidence that the block was originally manufactured as a 4 bolt main.
By 1973, big blocks had become pretty much a truck engine. Many trucks used 4 bolt main configuration. So, it's very possible that a block or blocks intended for truck use were used for some passenger car or Corvette LS-4 applications. An "upgrade" like this was considered acceptable. A "downgrade" (i.e. using a 2 bolt block in an application that was supposed to be 4 bolt) likley would not have occurred.In Appreciation of John HinckleyComment
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Re: 73 LS4 4bolt ...again...
Yeah, thanks Joe. I did leave out some stuff that was in an earlier post. The oil holes are correct for a 4bolt, and it has HP cast onto the driver side below the exhaust manifold. I've had other LS4s and 5's before, all were 2bolt capped, and did not have that cast onto the side. The only reason I would look at the tank sticker is to possibly find any other build info that I am not aware of... not to find out anything more about the cap configuration. Of 4412 LS4's that left the factory in 73, 3704 had 4spds and according to Alan Colvin in 'Chev by the Numbers' "several 4bolt 3999289 have been found, but they're an exception." The 3999289 block is from the same cast as the 3963512 LS6 block, the major differences being in how it was de-tuned for unleaded fuel. If a 4bolt version was meant for a truck... whatever, it ended up in my car at the factory with the correct codes. All I am trying to do is get as much info that I can.Comment
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