I just purchased a 69 corvette - I was aware that the motor was rebuilt in 88 and decked so the car has no vin on the engine. The car had not been driven since 1992.

Everything on this car is correct regarding date codes and casting numbers and or part numbers - tranny, rear, heads, intake, carbs, etc. The issue is the date code on the block.

The casting number on the block is correct for a 69 427/435HP. I have the protect plate and the engine number has the correct SUFFIX "LR" - so it should be a real car, I don't have a build sheet, but I am not sure that the block is correct based upon the date code.

This date code is on the passanger side below the freeze plug, which I read is where they sometime appear in 69. It looks like January 15, 1969 - well the production date for my car is December 69 (that is a fact based on the VIN and Trim tag).

Is it possible that the block was almost one year old and used in this car? Also, you can also look at this date code and it could be a 0? See picture.

This is the block casting number and potential applications:39635121969-71427335, 390, 400, 425 COPO, 430, 435,454345, 360, 365, 390, 425, 450 2&4 bolt
I have read on other sites that this block was used in late 69 vehicles. They had an extended production year in 69 going into December.

Looking for feedback?

Bob Messina

 

Hi Bob,

"Is it possible that the block was almost one year old and used in this car?"

Isn't it generally accepted that the casting date (and the engine assembly date) must precede the vehicle assembly date by no more than 6 months?

Perhaps someone with 69 427 knowledge will know if there were some exceptions to this thinking during 69 production for very late cars like yours (December 69 assembly).

What is the cars sequence number?

Regards,
Alan

 

You might also find a date code stamped into the starter mount pad.

 

The sequence number is vvvvvvv Will check the starter mount pad.

 

I have two late build '69 427 cars. One is September and the other is December. I have included a picture of one of my casting dates for comparison. Do you have a picture of the casting number? Do you know if your engine has 4-bolt mains? That would be another piece of the puzzle.

 

You could wire brush the paint off to see the cast #'S better but no mater what the date will not be right for your Corvette.

 

I tend to agree - there is another number above the casting number that I can't make out. But regardless - the number I have the picture of looks absolutely like the date code - I tend to agree - date codes does not look right under any circumstance.

 

Here is a picture of the other number that I can make out - any thoughts?

 

The casting date on big blocks was moved from the side of the block down by the freeze plug to the back of the block just above the bell housing flange sometime in April of 69 right around when the strike started so I think that would definitely be an early block. My 69 427 built in Oct of 69 has the casting date at the top rear of the block.

 

That makes total sense -

 

Hi Bob,
Many folks believe it's a poor idea to use ANYTHING abrasive or something like a wire brush to aid in removing the paint from stamp pads and dates/numbers cast into the block itself.

At this point you don't want to take ANY chance of DEGRADING the stamped/cast information or the surface of the pad or block any further.
Use only liquid or paste paint removers.

Regards,
Alan

 

Hmm is it me or does that last number look like an 8 making it 1968??? But that would make the block older than your car. Not good. Try to take photos at different angles and with and without light. you may get a better image. Ike

 

defiantly looks like a 8, 1-15-68, that would put that
block casting one year before your car was built

 

Looking at the top photo, I don't see anyway that's not an 8 in that date code. And an A which I assume is January. As far as, is it "possible" for the block casting date to be older than the manufacturing (assembly) date by a year? I have no idea what the numbers gurus in the hobby use for their official guidelines on whether or not that is an "acceptable" difference. I would tell you as someone who worked for 50 years in QA in manufacturing involving castings, forgings, machining, rework cycles, inventory transfers, etc. it would certainly be "possible" but probably not very likely in the case of automotive practices. I am aware of one auto assembly plant that typically had an engine inventory that was measured in hours, not days. So they tended to work pretty close to Just In Time manufacturing even in the old days. However, the random component could get sidelined and fall out of the cycle for a variety of reasons so pretty much anything is a possibility.

 

Not the correct block for described car.

 

ALAN
I agree that one should NOT wire brush any # that is stamped in a part but the date tag is cast in & is part of the casting. yes paint thinner would be better but wire brushing the #'S shouldn't hurt.
PS I have looked at a few 67 BB 351'S that had #'S changed. Wire brushing them makes it show up like a sore thumb.

 

It really does not matter at this point if the block was cast a year before the car was assembled.

The broad answer to the original question is that the block cast date is too far out for normative practice.

Wider date spread between engine assembly and vehicle assembly on low volume, high HP engine options is known BUT all the individual engine component casting dates should be closer together. If all the other engine components make sense on the date codes being closer to car assembly date but just the block date is way off.... How could that happen? A complete engine assembly can sit in the que but a empty block that was in common usage in other applications has no place to just "hang out" for a whole year.

The engine suffix stamp / VIN derivative is gone. The deck has been cut so the block will never be matching numbers. Vehicle value estimate would be for a non-original engine block Vette based on what is left. Nice to have the documentation for sure.

 

I have taken my '70 454 to an NCRS Chapter and Regional meet and Top Flighted the Chapter and Second Flighted the Regional. Body build date is F01, June 1st 1970, Casting date K79, Nov. 7, 1969, 3963512 casting for big block. Engine stamping T0525 CZU, Tonnawanda May 25, 1970, 4 speed car. I am not original owner but seller swears it's original motor. My problem is the casting date and engine build date are just over 6 months, which NCRS does not allow. The Regional judges were sure the engine stampings were good, so hard to explain non-typical time between casting and build at Tonnawanda. Any ideas how I can prove this was the motor the car was born with for the National meet in July. Any help would be appreciated.

 

Moondog01. My first suggestion is you should start another post of your own, you wil probably get better responses.

Second I am not expert but there were strikes at GM but I don't believe it fits your time frame. The sad answer is that it may not be the original engine to the car despite what the original owner says. How does he back up his statement? Build sheet?

Ike