Broach Marks and Pad Stamps

[Steven B.]

Re: Broach Marks and Pad Stamps

Steve,

Why not post a pic of your pad ?.....you'll get plenty of opinions here from some very knowledgeable folks..

Hi John. I have the pic. but having a software glitch I am working out. Vista

Steve

[Steven B.]

Re: Broach Marks and Pad Stamps

One pass, two surfaces at a time. The deck (2), oil pan rails, and top of block.

I was told by a GM employee that was familiar with the broach process that the difference in the "marks" was relative to the sharpness/dullness of the blade.

In principal, using wood working as an example, the broach tooling is nothing more than a 300 ton block plane. The force that it takes to move the block thru is tremendous. When one of the manufacturers started using thin wall casting, they had problems ripping the main bearing webs right out of the block. That area of the building literally shakes. I have been in the old Flint plant and the old IHC Ft. Wayne engine plant. In the 50's thru the '90's all the blocks were machined this way.

I believe F**d is the first US manufacturer to go with rotary machining when they started building their modular engines.

They must have been pretty smooth to begin with (no pits in the castings, etc.) since only a few .001's comes off at a time. I visited the IHC Ft. Wayne plant in the late 60's early 70's when I lived there. I had a friend in QC who introduced me to a guy there named Lingenfelter who liked cars. He was a smart guy.

When I worked at Maremont in Paulding, Ohio, the maintenance and set up guys used to take the small Leblond and shoot pennies into the wood wall.

[Alan S.]

Re: Broach Marks and Pad Stamps

Hi Steven,
Here's a picture of a bit later (71) 350.
Regards,
Alan

[Terry M.]

Re: Broach Marks and Pad Stamps

If you have pics of pads showing original broach marks and stamps can you please post? I have reviewed previous posts/pictures and I am looking for variations in the broach marks as the tools wore and also stamp variatons. Some are very pronounced while others are barely visible. Including the engine date would be great also. I am most interested in 265, 283, and 327 but all will give me a good idea.

Thanks!

Steve

Steve,

There is no assurance that the engines were assembled chronologically with respect to machining -- thus the engine assembly date has no relevance to their trip through the broach machine. And to complicate matters further, there is no assurance that the casting date (and time) has any relevance to the machining operation either.

I guess I am at a loss as to how any number of pictures of finished stamp pads will help you determine tool life.

[Robert G.]

Re: Broach Marks and Pad Stamps

Here's one that was on ebay that seemed to have a few questionable items related to dates and body numbers.

[Ronald R.]

Re: Broach Marks and Pad Stamps

This broach business is making some of us go backwards!! If you have the orig. numbers but a buffer has been used on the deck in the past, do you attempt tp replace the broach marks or just live with it? It seems foolis to try and replace marks that can be worn in the ordinary treatment of the old cars.
RDR

[Roy B.]

Re: Broach Marks and Pad Stamps

This broach business is making some of us go backwards!! If you have the orig. numbers but a buffer has been used on the deck in the past, do you attempt tp replace the broach marks or just live with it? It seems foolis to try and replace marks that can be worn in the ordinary treatment of the old cars.
RDR

You make a good point , when I was working on Corvettes at a Burbank Chevy dealer before replacing the heads after a valve job we would sand the block to clean the surface. Who worried about broach markings. And now they wont to see untouched blocks with all the many poor repro's parts out there?? On my 55 I got some many different opinions that I just give up.

I Suppose if the broach marks don't meet some ones satisfaction the Corvette is not worth much.

[Wayne M.]

Re: Broach Marks and Pad Stamps

Here's a scan of front and back covers of an old RESTORER; pics by John Amgwert. Good broach mark detail.

[James W.]

Re: Broach Marks and Pad Stamps

Steve,

Here are two pictures of Corvette 327 stamp pads; one on the left is my '64 327/300 (January 14, 1964 - St. Louis body build date was January 18th) and the middle and right pictures are my '65 327/350 (July 1, 1965 - A.O. Smith body build date was July 24th).

Regards,

James West

[Tom S.]

Re: Broach Marks and Pad Stamps

Does the pad on William Lacy's car look like a re-stamp? I see what looks like other #'s and letter 's there. Or is it a shadow? I have seen what looks like shadows before. I have also seen what looks like a stamp over after decking.Whats the deal with this one? Tom

[Dick W.]

Re: Broach Marks and Pad Stamps

Does the pad on William Lacy's car look like a re-stamp? I see what looks like other #'s and letter 's there. Or is it a shadow? I have seen what looks like shadows before. I have also seen what looks like a stamp over after decking.Whats the deal with this one? Tom

I will be the first to admit that I am about 1/2 blind, but after enlarging that photo 400% all I see is a couple of scratches.

[Pat M.]

Re: Broach Marks and Pad Stamps

Does the pad on William Lacy's car look like a re-stamp? I see what looks like other #'s and letter 's there. Or is it a shadow? I have seen what looks like shadows before. I have also seen what looks like a stamp over after decking.Whats the deal with this one? Tom

Looks to me like a light double stamp, or a light "jump" stamp.

[Michael W.]

Re: Broach Marks and Pad Stamps

Does the pad on William Lacy's car look like a re-stamp? I see what looks like other #'s and letter 's there. Or is it a shadow? I have seen what looks like shadows before. I have also seen what looks like a stamp over after decking.Whats the deal with this one? Tom

Typical factory 'bounce', not rare at all.

[Jean C.]

Re: Broach Marks and Pad Stamps

Tom,
Regarding the appearance of a double stamp on Bills pad. When I see this supposed "double" stamp on a pad, I figure the guy doing the stamping set the gang stamp on the pad, tapped it lightly with his hammer in order to take "dead aim" (thank you Harvey) then hit the stamp with a mighty blow. Thus a light impression and a heavy impression. Others say the ghost impression is the result of rebound of the hammer following the heavy hit. Whatever. Anyway, that's my story and I'm sticking to it.
Best regards,

[Steve B.]

Re: Broach Marks and Pad Stamps

Typical factory 'bounce', not rare at all.

I agree, just typical bounce on Bills pad.