70 Sill Plates

[Bill L.]

Well I was reviewing the archives and it seems the reproduction sill plates are a bit different from the originals. Something to do with the ribs.

What is the exact difference? I have what I believe are the originals and the only possible difference I see is the small ribs might be a little more well defined.

I am curious because NOS sill plates seems to go for a LOT of $$.

Thanks,


Bill

[Alan S.]

Re: 70 Sill Plates

Hi Bill,
Here's a comparison of an original sill plate from my 71 and a reproduction sill bought about 10 years ago.
The 2 arrows point at slight differences at those points. The upper arrow points at a difference that is PARTLY because of the way the black was applied to the original. A few of the striations were left unpainted.
The paint edges on the reproduction are more cleanly defined than on the original. Due to the mask used?
There also is the slight difference you mention in the definition of the 3 center ribs.
Are all the reproductions from one source?
Regards,
Alan

[Bill L.]

Re: 70 Sill Plates

Hi Bill,
Here's a comparison of an original sill plate from my 71 and a reproduction sill bought about 10 years ago.
The 2 arrows point at slight differences at those points. The upper arrow points at a difference that is PARTLY because of the way the black was applied to the original. A few of the striations were left unpainted.
The paint edges on the reproduction are more cleanly defined than on the original. Due to the mask used?
There also is the slight difference you mention in the definition of the 3 center ribs.
Are all the reproductions from one source?
Regards,
Alan

Thanks Alan.

Short of having them side by side it is tough to discern. Your pictures are exactly what I was hoping to see.

I think I will take the small hit, if there is one, for the minor differences.

There is a set on ebay now with two "private" ebay bidders ready to likely pay a ton of money for NOS sill plates. Already up over $200. Wow!

Thanks, Bill

[Alan S.]

Re: 70 Sill Plates

Hi Bill,
I think there's as much conversation about the size of the counter sink area for the screws, the size of the screw heads, and the way the heads 'nestle' into the countersink, as there is about the ribs.
So perhaps you can put your efforts into that aspect which won't likely cost you $200!!!
Regards,
Alan

[Patrick H.]

Re: 70 Sill Plates

Hi Bill,
I think there's as much conversation about the size of the counter sink area for the screws, the size of the screw heads, and the way the heads 'nestle' into the countersink, as there is about the ribs.
So perhaps you can put your efforts into that aspect which won't likely cost you $200!!!
Regards,
Alan

When I see them, the screw and countersinking problem always seems to be much more obvious than the ribs. The paint could likely be redone if you really, really wanted to in order to minimize that difference. I've repainted originals and it's not that difficult.

Patrick

[Bill L.]

Re: 70 Sill Plates

Hi Bill,
I think there's as much conversation about the size of the counter sink area for the screws, the size of the screw heads, and the way the heads 'nestle' into the countersink, as there is about the ribs.
So perhaps you can put your efforts into that aspect which won't likely cost you $200!!!
Regards,
Alan

I am pretty sure I have the correct screws. If memory serves me they are #10 screws with #8 head. Now were the screws flush with the sill plate or just slightly above?

THanks,


Bill

[Alan S.]

Re: 70 Sill Plates

Hi Bill,
My understanding is that the screw head should fill the countersink area but not extend beyond it in width.
I'd think because of the 'rise' in the head it would bring the center of the head slight above the surface of the plate.
Perhaps Patrick has a picture of the plate and screws in his 72 Bowtie pictures… have you looked there?
Regards,
Alan

This is from a 69 Bowtie car.
Note those last few striations to the right aren't painted on this plate either.
I wonder how typical that was?
How about this one…. how typical was it for the counter-sink operation to 'nick' the rib on each side of the hole?

[Bill L.]

Re: 70 Sill Plates

Hi Bill,
My understanding is that the screw head should fill the countersink area but not extend beyond it in width.
I'd think because of the 'rise' in the head it would bring the center of the head slight above the surface of the plate.
Perhaps Patrick has a picture of the plate and screws in his 72 Bowtie pictures… have you looked there?
Regards,
Alan

This is from a 69 Bowtie car.
Note those last few striations to the right aren't painted on this plate either.
I wonder how typical that was?
How about this one…. how typical was it for the counter-sink operation to 'nick' the rib on each side of the hole?

Alan,

Thank you.

The other interesting observation is that the small ribs are not all the same either.

I am pretty sure I can duplicate the painting by taping and lifting the edge of the tape so there is not a sharp line.

Frankly the repros I have are pretty good. I am not sure whose they are as I picked them up at a local Corvette Shop. The holes lined up perfectly, the holes were counter sunk, and the ribs look to be the same size. The paint job is too nice for TFP.


Bill

[Patrick H.]

Re: 70 Sill Plates

Frankly the repros I have are pretty good. I am not sure whose they are as I picked them up at a local Corvette Shop. The holes lined up perfectly, the holes were counter sunk, and the ribs look to be the same size. The paint job is too nice for TFP.


Bill

Bill,

If you can find out that would be nice. The last set of repros I installed were horrible.

Patrick

[Bill L.]

Re: 70 Sill Plates

Bill,

If you can find out that would be nice. The last set of repros I installed were horrible.

Patrick

I will ask and post the vendor if he tells me. He is usually pretty open.

Bill

[Gary B.]

Re: 70 Sill Plates

Make sure the screw heads fit flush with the surface. Aftermarket sill plates are not countersunk deep enough for the screws, and the screws sit to high.
Also, it is quite common to see the countersink tool to nick the ribs when machined. The holes were not always perfectly centered in the groove.
Gary Bosselman

DSCN3575.jpgDSCN3576.jpg

[Bill L.]

Re: 70 Sill Plates

Make sure the screw heads fit flush with the surface. Aftermarket sill plates are not countersunk deep enough for the screws, and the screws sit to high.
Also, it is quite common to see the countersink tool to nick the ribs when machined. The holes were not always perfectly centered in the groove.
Gary Bosselman

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Great pics Gary. MIne may need to be a little deeper. I will now have to double check.

Bill

[Rich C.]

Re: 70 Sill Plates

I bought an N.O.S. set several years ago for $80, and I thought that was a lot then. They are still in the GM bags. Wish I bought more, $200, geez, better rate of return than the annuity I have! Almost didn't buy them because I knew repros were available, but from your pics, I'm glad I did! Minus 50 wind chill this evening here in the Adirondacks yikes!!!

1973 LS-4 454 coupe owned 24 years
1996 LT-4 CE coupe
Victory Hop Devil Ale-currently on tap!

[Bill L.]

Re: 70 Sill Plates

I bought an N.O.S. set several years ago for $80, and I thought that was a lot then. They are still in the GM bags. Wish I bought more, $200, geez, better rate of return than the annuity I have! Almost didn't buy them because I knew repros were available, but from your pics, I'm glad I did! Minus 50 wind chill this evening here in the Adirondacks yikes!!!

1973 LS-4 454 coupe owned 24 years
1996 LT-4 CE coupe
Victory Hop Devil Ale-currently on tap!

I bet they go for closer to $300 in the end.

The repros I have look a lot better that the ones shown above and the holes lined up perfectly. I will try and get some pictures.

The paint is not right but the counter sink looks very similar to the originals in Gary's photo. However, the ribs are not nicked.


Bill

[Erich M.]

Re: 70 Sill Plates

Well I was reviewing the archives and it seems the reproduction sill plates are a bit different from the originals. Something to do with the ribs.

What is the exact difference? I have what I believe are the originals and the only possible difference I see is the small ribs might be a little more well defined.

I am curious because NOS sill plates seems to go for a LOT of $$.

Thanks,


Bill

Bill,

Dave Strickland and I were discussing the sill plate screws last year. I am the original owner of a 72 Bowtie car. Attached are some pictures. The screws are .321" diameter with a slight chamfer at the OD of the head. My screws are not flush with the sill but stick up slightly (no more than 1/32") when I put a straight edge on top of the head.

Erich Meyer
72 LT1 Bowtie & Top FlightDOOR SILL SCR .321 001.jpgDOOR SILL SCR .321 002.jpgDOOR SILL SCR .321 003.jpgDOOR SILL SCR .321 004.jpg