Re: When Did Broach Marks Stop?
When the Small Block was introduced by Chevrolet the broach machine (Made by what was then called Cincinnati Milling Machine) was heralded in a press release for the flat plane of the surface as well as the surface finish; as a means of ensuring sealing between the cylinder case and the head surface. What we evaluate as "broach marks" are the surface finish referred to in that release. I wish I had access to that release, but I do not have a copy. I have seen it, but can't remember where or when. Perhaps someone with access to the Heritage Center may be able to hunt it down.
As an ancillary question: How were the 6-cylinder stamped surfaces machined? Not being part of a sealing surface makes the quality of the surface is less relevant, but I still have to ask.
When the Small Block was introduced by Chevrolet the broach machine (Made by what was then called Cincinnati Milling Machine) was heralded in a press release for the flat plane of the surface as well as the surface finish; as a means of ensuring sealing between the cylinder case and the head surface. What we evaluate as "broach marks" are the surface finish referred to in that release. I wish I had access to that release, but I do not have a copy. I have seen it, but can't remember where or when. Perhaps someone with access to the Heritage Center may be able to hunt it down.
As an ancillary question: How were the 6-cylinder stamped surfaces machined? Not being part of a sealing surface makes the quality of the surface is less relevant, but I still have to ask.
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