1970 LT1 engine pad

[Jeff W.]

I am looking into a 70 LT1 and would appreciate your advice on the VIN derivative stamping on the engine pad on an engine with July 1970 casting and assembly dates. The VIN derivative starts 10S4xxxxx. The VIN at the windshield is 70S4xxxxx. The build number of the car is the same in both areas. All other numbers and build dates on the engine match up (except for the carb which is wrong). I know that the TIMJG says it should start with a 7, but is it possible that it was stamped this way at the factory? I am waiting on a picture of the stamp pad.
Thanks for the help.
Jeff

[Terry M.]

Re: 1970 LT1 engine pad

Get the picture. Someone may be miss-reading it -- or it may be the most obvious sign of some other monkeying around.

If it was stamped that way at St. Louis it is likely the transmission would have the same stamp (they were done by the same person, with the same stamp holder, at the same workstation). It is also likely there would be a number of other Corvettes around the same VIN number stamped the same way.

[Jeff W.]

Re: 1970 LT1 engine pad

I will be seeing the car Saturday morning so I will get some pics and other info to update.
Thanks

[D S.]

Re: 1970 LT1 engine pad

From the 1970 Corvette Registry: http://www.1970corvetteregistry.org/..._enginepad.jpg

[Terry M.]

Re: 1970 LT1 engine pad

Unfortunately those are from the opposite end of the 1970 model year than what Jeff is looking at -- or will be looking at. But they are nice pictures, none the less.

[Chuck S.]

Re: 1970 LT1 engine pad

I will be seeing the car Saturday morning so I will get some pics and other info to update.
Thanks

Comparing the engine component casting dates (as many as you can see) to the engine assembly date will provide some insight into the engine's authenticity. Major components' casting dates are likely to be within a week of engine assembly date; some may be within days. Other components like exhaust manifolds are likely to be months prior to assembly. Finding and reading the date codes for the exhaust manifolds would be a trick anyway, as will those for the heads (you may be to see one through the oil fill opening).

Comparing the engine build date with the car's build date will add additional confirmation of authenticity, assuming you can attribute the stamp inconsistency to factory anomaly. You didn't reveal the engine and car build dates, but based on any "July" engine assembly date, the car's build date should probably be within the last three weeks of July. To give you an idea of the time between engine and car build dates, my base engine was built 0708, and the car was built G30. Optional engines can sometimes be longer between engine assembly and car build, but based on this case, that would appear not to be true for LT1s in late 70 (a little investigation to confirm this might be in order; see below).

You can also check LT1 engine build dates around this VIN on Juliet's 70 Registry page. I would expect the LT1 build dates shown there to be grouped fairly closely to this engine build date for any car VIN near this VIN.

[John H.]

Re: 1970 LT1 engine pad

The VIN derivative starts 10S4xxxxx. The VIN at the windshield is 70S4xxxxx. I know that the TIMJG says it should start with a 7, but is it possible that it was stamped this way at the factory?

Jeff -

The format of the VIN derivative stamped on the engine is different than the format of the full VIN on the windshield pillar.

The full VIN on the pillar would be like 194670S4xxxxx, but the VIN derivative starts with a "1" for Chevrolet, a "0" for 1970, an "S" for St. Louis, then the 4xxxxx.

Edit: Ignore my comment on the derivative format - it does start with a "7", not with a "1".

[Chuck S.]

Re: 1970 LT1 engine pad

Jeff -

The format of the VIN derivative stamped on the engine is different than the format of the full VIN on the windshield pillar.

The full VIN on the pillar would be like 194670S4xxxxx, but the VIN derivative starts with a "1" for Chevrolet, a "0" for 1970, an "S" for St. Louis, then the 4xxxxx.

John, I know that some years start with a "1", and I looked in the NCRS spec book to determine which years (couldn't find the VIN derivative format). But in 70...the VIN derivative starts with a "7" on engine and tranny. (You made me go check my written records and the engine! ) I have no idea why...maybe just another special "touch" for 70s.

The guy that stamped this car must have be filling in, and hadn't yet stamped a 70 pad.

[Terry M.]

[Terry M.]

Re: 1970 LT1 engine pad

I doubt it Chuck, but let's wait for the evidence.

[Kenneth H.]

Re: 1970 LT1 engine pad

Jeff,

Here's a pic of my '70 LT1 pad. The only difference will be that the broadcast code for a July build should be CTK instead of CTU as on mine, which will indicate the change from the 6 quart oil pan to the smaller 5 Quart oil pan to allow room for the power steering unit.

[Chuck S.]

Re: 1970 LT1 engine pad

I doubt it Chuck, but let's wait for the evidence.

You're right of course. I should be more careful about what I say. Odds are they would have "fixed" a problem of this nature before it left the plant.

[John H.]

Re: 1970 LT1 engine pad

John -- Oops -- it is another C3 thing.

Oops - serves me right for commenting on a C3 issue I'm not "sure" about; learned something new (to me) today.

[Dave S.]

Re: 1970 LT1 engine pad

I am looking into a 70 LT1 and would appreciate your advice on the VIN derivative stamping on the engine pad on an engine with July 1970 casting and assembly dates. The VIN derivative starts 10S4xxxxx. The VIN at the windshield is 70S4xxxxx. The build number of the car is the same in both areas. All other numbers and build dates on the engine match up (except for the carb which is wrong). I know that the TIMJG says it should start with a 7, but is it possible that it was stamped this way at the factory? I am waiting on a picture of the stamp pad.
Thanks for the help.
Jeff

Jeff,
My 70 LT-1 is a July 8 build. VIN 14803. Is that close enough.????

[Jeff W.]

Re: 1970 LT1 engine pad

OK guys, here we go. The pics are the best I could get and it does show a 1 instead of a 7. The tranny is a P0K1(or 4)B with a Vin derivative of 70S4xxxxx. The block is a 3970010 G10 (july 1970) so that matches up. The heads are 3927186 G10 and that matches up. Intake looks to be correct as the numbers are underneath. Exhaust manifolds are correct even though I had a hard time seeing the casting date it looked to be 1970. Altenator is a 1100884, date 0F29 so that puts it at June 29, 1970.
So, what do we make of the engine pad. This is where you guys earn the big bucks.
Thanks for the help
Jeff