Can this 1970 LS-5 block casting date be original to the car?

[John H.]

Re: Can this 1970 LS-5 block casting date be original to the car?

Is there a write up of the rework/scrap processes for Corvette production, how this caused stuff to be routed between St. Louis and its feeder factories, and the resulting WIP cycle times? This might help us appreciate what date combinations are possible.

Mark -

Here's how the system worked. Engines weren't repaired at St. Louis - if an internal issue was found at car-start or subsequently at Roll Test, the engine was pulled in Heavy Repair and returned to the engine plant for credit, and another engine was run down the Engine Dress Line to replace it. St. Louis personnel weren't trained or equipped to perform internal engine repairs, and were prohibited from doing so by the engine plants' warranty and credit return policy.

The failed engine was then repaired at the engine plant, the pad stampings were ground off, and the machine code was restamped, and the engine was returned to the assembly plant for use in production, which included a fresh VIN derivative stamping.

[Michael W.]

Re: Can this 1970 LS-5 block casting date be original to the car?

So to answer your question, even though the car is set up as a nice driver, I want to know if the engine is original. I'm not an NCRS judge, but maybe it could achieve flight (3rd?, 2nd?) by putting the original bits back on, and installing reproduction tires/belts/hoses. But who knows? It has a lot of reproduction interior and trim parts so it may not do so well.

Be aware that the Flight Judging process does not determine if or certify that an engine is the factory original. There are some circumstances where an engine that is the original may have some or all points deducted for the stamp pad. Since your engine is far from typical in terms of dates and pad features, it may just run afoul of how the rules are applied.

I wouldn't let this factor deter you from having the car judged as the experience first time out is more to learn about the car than worrying about the colour of an award ribbon.

[Paul O.]

Re: Can this 1970 LS-5 block casting date be original to the car?

My feeling looking at all the photos to me indicate a engine problem at Tonawanda. Engine goes to heavy repair at plant. As part of the repair employee grinds out stamping. But as in some cases the employee is one that grinds the pad from one side to the other. Verses when just the Suffix code is ground out. Which then causes the the problem we see in these photos. As Patrick stated a much higher resolution photos are needed to make a more accurate judgement. Also as John has stated it could also have been returned from St. Louis or it could also have taken that long to come out of the heavy repair shop at Tonawanda if it had failed there. Just my 4 cents you know inflation.

[Mark E.]

Re: Can this 1970 LS-5 block casting date be original to the car?

Mark -

Here's how the system worked. Engines weren't repaired at St. Louis - if an internal issue was found at car-start or subsequently at Roll Test, the engine was pulled in Heavy Repair and returned to the engine plant for credit, and another engine was run down the Engine Dress Line to replace it. St. Louis personnel weren't trained or equipped to perform internal engine repairs, and were prohibited from doing so by the engine plants' warranty and credit return policy.

The failed engine was then repaired at the engine plant, the pad stampings were ground off, and the machine code was restamped, and the engine was returned to the assembly plant for use in production, which included a fresh VIN derivative stamping.

Thanks John.

So from what you're saying, here's my understanding of the process steps from block casting to when a repaired engine's pad is re-stamped with its new assembly date (re-work date) when the engine defect is found in St. Louis:

Block Cast (@ Engine Plant) ==> Engine Assembled & Tested (@ Engine Plant) ==> Engine Shipped to St. Louis ==> Engine Installed in Car (@ STL) ==> Engine Problem Detected (@ STL) ==> Engine Removed from Car (@ STL Heavy Repair) ==> Engine Shipped Back to Engine Plant ==> Engine Repaired; Assy Date and Suffix Restamped (@ STL Heavy Repair)

How long did this take? Thee months? Six months? Nine months (as my dates suggest)? Sometimes longer?

[Paul B.]

Re: Can this 1970 LS-5 block casting date be original to the car?

...just as an example, years ago a friend had a very early '71 LS-5 automatic coupe VIN#033XX, which had a trim tag build date of 12-7-70, motor was cast around 4-3-70, had an assembly date around 4-25-70. Car got Bloomington Survivor and the judges, many who were very high point NCRS Master Judges thought the engine was 100% original to the car. We also got to check several other early '71 LS-5 cars during the time period he owned the car and we found a couple of others that the engine was cast well over 6 months prior to the body build date of the car.

[John H.]

Re: Can this 1970 LS-5 block casting date be original to the car?

Thanks John.

So from what you're saying, here's my understanding of the process steps from block casting to when a repaired engine's pad is re-stamped with its new assembly date (re-work date) when the engine defect is found in St. Louis:

Block Cast (@ Engine Plant) ==> Engine Assembled & Tested (@ Engine Plant) ==> Engine Shipped to St. Louis ==> Engine Installed in Car (@ STL) ==> Engine Problem Detected (@ STL) ==> Engine Removed from Car (@ STL Heavy Repair) ==> Engine Shipped Back to Engine Plant ==> Engine Repaired; Assy Date and Suffix Restamped (@ STL Heavy Repair)

How long did this take? Thee months? Six months? Nine months (as my dates suggest)? Sometimes longer?

Mark -

The engine was repaired and the machine code restamped at the engine plant, not at St. Louis; when the engine was used at St. Louis, it was VIN-stamped on the Engine Dress Line just like any other engine. The engine plant repair process could take as little as a few days, or it might take months, depending on the nature of the repair and the availability of manpower to sort through the returns, determine the nature of the repairs required, and actually perform the repairs. Tonawanda and Flint V-8 each built 5,500 engines every day (300 per hour), and repairing returns was pretty low on their priority list in terms of managing manpower resources.