LS5 454 two or four bolt main? or BOTH

[Joe L.]

Re: LS5 454 two or four bolt main? or BOTH

Thanks Joe for the clarification. Another thing I like to know is if you personally seen the examples of the LS5s with the four bolt mains, or have you read the reports like I have been on the internet. I especially like to know if you seen any 1971 LS5 4 bolt mains at any events you particiapated in? Or is this something that isn't even addressed? Also, for Joe or anyone, how would this play out during judging on a LS5 that appears to be a four bolt main? Is this something that would not even be evaluated as four bolt mains were built at Tonawanda. Assuming of course the stamp pad for the car in question is typical factory production and all casting numbers and dates are appropriate for the build date of the car.

Marc------


Yes, I have personally seen both 1969 L-36 and 1970 LS-5 with 4 bolt mains. However, I've never seen a 1971 LS-5 with 4 bolt mains. They may well exist but I've not seen one.

[Marc S.]

Re: LS5 454 two or four bolt main? or BOTH

Marc------


Yes, I have personally seen both 1969 L-36 and 1970 LS-5 with 4 bolt mains. However, I've never seen a 1971 LS-5 with 4 bolt mains. They may well exist but I've not seen one.

Joe, found something quite interesting. Looks like 4 bolt mains were not limited to the Corvette. There are reports on another model. I find it interesting with what is becoming many examples that the overwhelming literature does not support LS5's with 4 bolt mains and it is just limited to personal accounts of owning such examples. I really like to know why?

http://www.chevelles.com/forums/showthread.php?t=210665

[Joe L.]

Re: LS5 454 two or four bolt main? or BOTH

Joe, found something quite interesting. Looks like 4 bolt mains were not limited to the Corvette. There are reports on another model. I find it interesting with what is becoming many examples that the overwhelming literature does not support LS5's with 4 bolt mains and it is just limited to personal accounts of owning such examples. I really like to know why?

http://www.chevelles.com/forums/showthread.php?t=210665

Marc------


4 bolt main big blocks were absolutely not limited to Corvettes. Any 1965-71 special high performance big block (i.e. big block with mechanical lifters) used 4 bolt mains. This was regardless of the model vehicle in which it was installed. 1966 Chevelles with L-34 (i.e. 360 HP) were 4 bolt mains. Some later high performance big blocks with hydraulic lifters (e.g. L-36, LS-5) were also equipped with 4 bolt mains.

Why did the non-SHP big blocks have 4 bolt mains? Well, for 1969-70 I theorized a possible reason above. For the other years, I don't know. However, I don't think it was by accident or, as some have postulated, because GM had a bunch of 4 bolt blocks laying around and "used them up" on non-SHP engines. Generally, 2 bolt and 4 bolt big blocks used the same block castings----only the caps were different. While block castings may have piled up at the foundry or engine plant, the caps were installed as part of finish machining and assembly. In fact, in at least the case of the 4 bolt caps, they were not even cast at the Tonawanda foundry. By the time of finish machining, the final configuration of the engine was pretty much "dialed in".

[Marc S.]

Re: LS5 454 two or four bolt main? or BOTH

Marc------


4 bolt main big blocks were absolutely not limited to Corvettes. Any 1965-71 special high performance big block (i.e. big block with mechanical lifters) used 4 bolt mains. This was regardless of the model vehicle in which it was installed. 1966 Chevelles with L-34 (i.e. 360 HP) were 4 bolt mains. Some later high performance big blocks with hydraulic lifters (e.g. L-36, LS-5) were also equipped with 4 bolt mains.

Why did the non-SHP big blocks have 4 bolt mains? Well, for 1969-70 I theorized a possible reason above. For the other years, I don't know. However, I don't think it was by accident or, as some have postulated, because GM had a bunch of 4 bolt blocks laying around and "used them up" on non-SHP engines. Generally, 2 bolt and 4 bolt big blocks used the same block castings----only the caps were different. While block castings may have piled up at the foundry or engine plant, the caps were installed as part of finish machining and assembly. In fact, in at least the case of the 4 bolt caps, they were not even cast at the Tonawanda foundry. By the time of finish machining, the final configuration of the engine was pretty much "dialed in".

Did you happen to work at Tonawanda? I do not know your history so that is why I am asking?

Do you know of anyone who is on this forum, or elsewhere that actually worked the assembly line or
was a manager during these years at the plant? Surely, someone from that era could remember if these "LS5 4 bolt mains" were
produced for 1971 cars? I know you seen 1969 and 1970 original examples. I am simply trying to find out the why and you
made some very good conclusions. I would like to contact someone who was there and may have some more information
and may even have some tangible documentation. Thanks Joe for checking in!

[Joe L.]

Re: LS5 454 two or four bolt main? or BOTH

Did you happen to work at Tonawanda? I do not know your history so that is why I am asking?

Do you know of anyone who is on this forum, or elsewhere that actually worked the assembly line or
was a manager during these years at the plant? Surely, someone from that era could remember if these "LS5 4 bolt mains" were
produced for 1971 cars? I know you seen 1969 and 1970 original examples. I am simply trying to find out the why and you
made some very good conclusions. I would like to contact someone who was there and may have some more information
and may even have some tangible documentation. Thanks Joe for checking in!

Marc------


No, I never worked at Tonawanda or, for that matter, in the automotive industry, at all. However, I have toured both the Tonawanda and Flint engine plants.

Ken Kayser who is an NCRS member once was a supervisor on the big block line at Tonawanda. Whether he would know the answer to your question, I don't know. There are at least one or two other guys that worked at Tonawanda that frequent this board. I don't recall their names but maybe they will see this and check in.

[Mike E.]

Re: LS5 454 two or four bolt main? or BOTH





If I'm reading the early May to late August date spread from the casting date to the engine assembly date in Thomas's example above that might support the inventory glut theory. I know in the mid sixties the casting date and assembly dates on small blocks were only a few days typically. Also I recall there was a mild recession in 1970 that could cause inventories to go wacko. This could also explain some odd things going on in big block production. Usually when a downturn occurred back then Corvettes and high performance cars were effected first.

Mike

[Joe L.]

Re: LS5 454 two or four bolt main? or BOTH

If I'm reading the early May to late August date spread from the casting date to the engine assembly date in Thomas's example above that might support the inventory glut theory. I know in the mid sixties the casting date and assembly dates on small blocks were only a few days typically. Also I recall there was a mild recession in 1970 that could cause inventories to go wacko. This could also explain some odd things going on in big block production. Usually when a downturn occurred back then Corvettes and high performance cars were effected first.

Mike

Mike-------


As I mentioned, block CASTINGS might sit around for awhile. However, for the most part these could be finished into either 2 or 4 bolt main configuration. I believe the decision as to whether the block would be finished into a 2 or 4 bolt configuration was made AFTER the block was taken out of any inventory of castings. At that point, the final configuration of the engine was pretty much set as there was only a few hours from that time until the engine was completed.

[Thomas H.]

Re: LS5 454 two or four bolt main? or BOTH

Let me throw one other odd thing into the mix. The front of my block has a dowel pin or plug of sorts welded into the block at an angle. You can see it sticking out of the pass side front.





Tom

PS (for some reason the picture upload is not working for me and I need to use the photobucket links)

[Joe L.]

Re: LS5 454 two or four bolt main? or BOTH

Let me throw one other odd thing into the mix. The front of my block has a dowel pin or plug of sorts welded into the block at an angle. You can see it sticking out of the pass side front.





Tom

PS (for some reason the picture upload is not working for me and I need to use the photobucket links)

Tom------


I'm not sure what you're referring to. However, if you mean the zinc plated, square drive plug seen at the upper left in your second photo, that's the plug for the main oil gallery. All Mark IV big blocks except ZL-1 have the main oil gallery in the right side pan rail. For Gen V and Gen VI big blocks, the main oil gallery was moved to adjoining the cam tunnel, like ZL-1 and all small blocks.

[Thomas H.]

Re: LS5 454 two or four bolt main? or BOTH

Tom------


I'm not sure what you're referring to. However, if you mean the zinc plated, square drive plug seen at the upper left in your second photo, that's the plug for the main oil gallery. All Mark IV big blocks except ZL-1 have the main oil gallery in the right side pan rail. For Gen V and Gen VI big blocks, the main oil gallery was moved to adjoining the cam tunnel, like ZL-1 and all small blocks.

Joe,

I should have bee a little more descriptive........... Looking at the picture where the block is upside down, on the right, between the lower water pump mounting hole and the accessory hole near the bottom of the block is an area where the casting is flat. Just about in the center of this area is a protrusion that sticks out about 3/8". The other side does not have this and I don't recall other big blocks I have looked at having this either.

Tom

[Marc S.]

Re: LS5 454 two or four bolt main? or BOTH

Marc------


No, I never worked at Tonawanda or, for that matter, in the automotive industry, at all. However, I have toured both the Tonawanda and Flint engine plants.

Ken Kayser who is an NCRS member once was a supervisor on the big block line at Tonawanda. Whether he would know the answer to your question, I don't know. There are at least one or two other guys that worked at Tonawanda that frequent this board. I don't recall their names but maybe they will see this and check in.

Good morning Joe.....

Thanks for the information. I will try to get a hold of Ken Kayser. If anyone has any contact information please send to my inbox. (eg. email address). Thanks.

[Joe L.]

Re: LS5 454 two or four bolt main? or BOTH

Joe,

I should have bee a little more descriptive........... Looking at the picture where the block is upside down, on the right, between the lower water pump mounting hole and the accessory hole near the bottom of the block is an area where the casting is flat. Just about in the center of this area is a protrusion that sticks out about 3/8". The other side does not have this and I don't recall other big blocks I have looked at having this either.

Tom

Tom-------


That is some sort of casting "artifact". It has no significance, at all, that I know of. It was probably a feature of the particular pattern that the sand molds for your block were made from. I can guarantee you that if your block has it, there are other blocks that also have it. Perhaps a small minority but there were certainly other blocks cast from the same pattern.

[Paul D.]

Re: LS5 454 two or four bolt main? or BOTH

I'll throw this out there....I have a 1970 Nova SS396(402").....350hp #854 block with 4 bolt mains and has the two oil cooler plugs on the side.....Documented from Canada,sold new in Calgary....