Broach Marks

[Steven C.]

I'm fairly certain my '69 L71 came to me with its original engine. I'm learning about broach marks, and found the NCRS definition:

"Broach Marks
The marks on the deck of the block including the stamp pad, created by the factory machining operation. Broach tool; leaves lines as the cutter moves across the deck in a straight line from front to back."

I think I know what that means, but I want to be certain. Mine looks like this, with lower-case L's depicting the broach marks:

llllllllllllllll
0325LX S19722XXX
llllllllllllllll

The definition also talks about left to right broach marks on restamps, I presume that would look like:

________________
0325LX S19722XXX
________________

Help is always appreciated.

Steve

[mike cobine]

Re: Broach Marks

Pretty much like you say. The lines should be straight from the back to the front without a curve.

Here are some that have a curve, where they have been cleaned up with a rotary sander/grinder.

I can't see the original so I don't know if this was decked and restamped or just cleaned down with a sander. You do NOT want this.

Naturally, since you want to see original pads, I can't find one anywhere.

[mike cobine]

Re: Broach Marks

Pretty much like you say. The lines should be straight from the back to the front without a curve.

Here are some that have a curve, where they have been cleaned up with a rotary sander/grinder.

I can't see the original so I don't know if this was decked and restamped or just cleaned down with a sander. You do NOT want this.

Naturally, since you want to see original pads, I can't find one anywhere.

[Steven C.]

Re: Broach Marks, pics, anyone?

Thank you Mike, I appreciate your response.

If you (or anyone else) can post a picture of an original stamp pad, I'd appreciate it.

[Rob Edwards]

Re: Broach Marks, pics, anyone?

For what it's worth, here's a recent thread on my stamp pad with a pic and comments:

https://www.ncrs.org/forum/archive22.cgi?review=175316

'62-340 stamp pad

[Steven C.]

Re: Broach Marks, pics, anyone?

Thank you, Rob. Quite helpful. (And it looks my broach marks were made by GM!)

[Dave McDufford]

Re: Broach Marks, pics, anyone?

Here is another example of the broach marks. Once you have cleaned the surface off, spray WD40 or something else on it to keep it from rusting.

Dave

[Bill Stephenson]

Re: Broach Marks

Mike,

--------I can pretty much guarantee that that "C" wasnt on the pad originally. What was someone thinking?.........Bill S

[paul bowers]

Re: Broach Marks, pics, anyone?

dave,
while we are on broach marks i have a (?) maybe someone can answer, when i had my block out of the car i could see the letters & no.s on the glock fairly easy but now that it is the car looking down i can not make them out so is there anything that can be put on the pad area to kind of enhance the letters just so they can be seen a litle better the pad is clean just real faint thanks
paul

[mike cobine]

Re: Broach Marks

If you notice, that is a T block and not an F, so it was not a Corvette block. That C is WAY off, so most would think it a restamp. Also, the 1 and 9 are not the same as Dave's picture, but then different plants could have had different fonts.

Offhand I can't think of what assembly plant is C and too lazy to go in the other room to look it up.

It isn't mine, btw, so I can't tell you it is right or wrong with 100%.

[John H.]

Re: Broach Marks

"C" was Lansing (Oldsmobile home plant).

[mike cobine]

Re: Broach Marks

Not too likely a Chevy small block being in an Oldsmobile back in '68, eh?

[John H.]

Re: Broach Marks

Not hardly!