Is this the correct dated block for my car?

[Joe L.]

Re: Is this the correct dated block for my car?

Jack,

Thanks for your 2 cents. I agree with your comments. I have been searching for a 351 block since I bought this car 6 months ago. The 2 bolt mains are even harder to come by than the 4 bolt mains. I have only found one with an "April 67" build date and the price was $6300 for a bare block. I'm sorry, I have a passion for my car, but that's a ridiculous price. The one I'm looking at is $2700, and it's a complete short block with crank, pistons, cam etc... I think I'll be purchasing this block. I can live with the build date and so can NCRS. So, what's not to like?

Thanks again. Chuck

Chuck------


I TOTALLY agree and that's why I made my initial recommendation to go with this block. The ONLY relevance of component dating, including blocks, is from a judging perspective. There is NO other relevance. If a block conforms to the date range from applicable judging guidelines, that's all that matters. Period. As I mentioned and as you also mentioned, a block dated within several weeks of the car's build date will not score one iota better than one that's 6 months out. You are not attempting to "re-create" the original engine or, even, imply that the engine in the car is original. So, all that really matters is if it conforms to the judging standards.

If you were talking about deciding between the purchase of several engines which all fell, date-wise, within the judging standards and all were about the same cost, then I would say go with the one that had a better date. But, that's not the situation. You are faced with the situation of having an engine available at a relatively reasonable cost and which falls within the judging standards, date-wise. I say JUMP ON IT. You snooze, you may lose!

[Ronald L.]

Re: Is this the correct dated block for my car?

John,
Nobody even nibbled on that one...

[Richard M.]

Re: Is this the correct dated block for my car?

John,
Nobody even nibbled on that one...

I just read this whole thread, interesting one that it is, and I got stumped when I read John's words........

Ok John, I'll bite, how can you tell (2 or 4 bolt) looking over the fender?

"PASS HI PERF" casting in the block = 4?

Rich

[Joe L.]

Re: Is this the correct dated block for my car?

I just read this whole thread, interesting one that it is, and I got stumped when I read John's words........

Ok John, I'll bite, how can you tell (2 or 4 bolt) looking over the fender?

"PASS HI PERF" casting in the block = 4?

Rich

Rich------


The configuration of the tapped fittings above the oil filter is different for the 2 and 4 bolt blocks. The 4 bolt block uses larger NPT tappings designed for use with an oil cooler. Curiously, it would be possible to reconfigure a 2 bolt block to mimic the 4 bolt block simply by drilling out and retapping the two fittings. However, it's not possible to reconfigure a 4 bolt block to a 2 bolt configuration.

The difference in this configuration can be easily seen by looking down from the driver's side fender. I think it can also be seen when looking through the fender louvers on 1965-66 and 1968-69. I don't know if it can be seen through the louvers on a 1967, or not.

[Richard M.]

Re: Is this the correct dated block for my car?

Ahhhhhh, right. Thanks Joe. I should know this. I just spent several months working on one. I had to thread that big plug in there!

[Charles S.]

Re: Is this the correct dated block for my car?

Again, My very deep appreciation for eveyone who responded. I have learned alot in just two short days. My goal is not to misrepresent this car in any way. I'm not trying to one day pass this off as an original factory engine car. It is however a real big block car and that's all that matters to me. Lastly, I would like to have the car judged through NCRS Flight Judging at some point and want to restore the car within NCRS guidelines. The January dated block I'm looking at falls within those guidelines. If we believe in the Noland Adams Book of compiled data from supposedly original cars and owners, it even list 67 Corvettes with "May" build dates and "January" casting dated blocks. Just as important, the price is extremely reasonable based on what I have seen on the market. I'm going for it!

Chuck Smith

[Ronald L.]

Re: Is this the correct dated block for my car?

Joe,
Right on, so interesting the subtle things that separated these.

[Richard M.]

Re: Is this the correct dated block for my car?

Again, My very deep appreciation for eveyone who responded. I have learned alot in just two short days. My goal is not to misrepresent this car in any way. I'm not trying to one day pass this off as an original factory engine car. It is however a real big block car and that's all that matters to me. Lastly, I would like to have the car judged through NCRS Flight Judging at some point and want to restore the car within NCRS guidelines. The January dated block I'm looking at falls within those guidelines. If we believe in the Noland Adams Book of compiled data from supposedly original cars and owners, it even list 67 Corvettes with "May" build dates and "January" casting dated blocks. Just as important, the price is extremely reasonable based on what I have seen on the market. I'm going for it!

Chuck Smith

Chuck, Good for you. All the best in your efforts!

It appears you have a well documented car and are doing it right. If you interpret the Purpose of the NCRS, what you are doing is precisely that. From the JRM: ".....owners who have preserved or restored their Corvettes to factory original appearance and function."

Many people are here to help. I had my very first big block experience over the last few months. I learned so much from the folks right here and some close friends. It was a phenomenal learning experience.

When you progress with the project please keep us up to date...... and pictures are always fun too!

Rich

[Jack H.]

Re: Is this the correct dated block for my car?

Good, you understood what I was saying!

That's why we have two judging categories: restored vs. unrestored cars. Flight judging is for restored cars and everyone knows that what's being presented is 'put together' in some form/fashion. So, let the rules work for you!!!

On your citing Noland Adams, way back when I did a statistical analysis of his Vol 2 survey data. VIN, interpolated build date versus reported key component date codes. It's been a long time, but my recollection is the MEAN interval was 5-weeks prior for those parts but the standard deviation was MIND BLOWING (something like 8-9 weeks).

Figure the typical Gaussian curve (although a Poission distribution would/should better apply) comprehends a spread of three standard deviations in either direction from the mean to capture the lion's share of a given process's typical variance and the NCRS 6-month rule starts to make REAL sense!!!

Another way to view the results of this analysis, is that while the typical time interval was 5-weeks prior, virtually all cars had one or more components that were way away from the mean...the product of lack of FIFO/LIFO inventory control and radom selection.

That says the next time you judge a car and find EACH AND EVERY dated component lines up nice and tight along the 5-week mean, there's a high likelihood that this car's dated parts have been replaced during the restoration process...

[Dick W.]

Re: Is this the correct dated block for my car?

Good, you understood what I was saying!


On your citing Noland Adams, way back when I did a statistical analysis of his Vol 2 survey data. VIN, interpolated build date versus reported key component date codes. It's been a long time, but my recollection is the MEAN interval was 5-weeks prior for those parts but the standard deviation was MIND BLOWING (something like 8-9 weeks).

Figure the typical Gaussian curve (although a Poission distribution would/should better apply) comprehends a spread of three standard deviations in either direction from the mean to capture the lion's share of a given process's typical variance and the NCRS 6-month rule starts to make REAL sense!!!

Another way to view the results of this analysis, is that while the typical time interval was 5-weeks prior, virtually all cars had one or more components that were way away from the mean...the product of lack of FIFO/LIFO inventory control and radom selection.

My head hurts Jack.

With that said, it fits the judging guide lines, it makes a lot of economic sense, and if that is what you want......Go for it. It is your car to do as you like with.

[Jerry B.]

Re: Is this the correct dated block for my car?

Maybe alittle off subject, I have a 57 (SEPT/56 build) 283 with a J8 283 build date. I lealize this is within weeks of the s/n 0214. However, with introduction of the 283 in early 1956, I would not think there was a large inventory built up. THOUGHTS!

[William C.]

Re: Is this the correct dated block for my car?

Many engines were within a week or two from casting to the installation in a car, but there are a lot of variables involved. Configuration (base engines move a lot faster than odd-ball combinations) last in-first out practices at the engine assembly plant, and assembly plant, and other things. When we first wrote the midyear judging manuals back in the early 80's, we tried to reach a happy medium that would not exclude an original car that was a genuine outlier, and also allow some latitude for an owner faced with the purchase of parts for a true "restoration" Looks like we maybe didn't due too badly some almost 30 years ago.

[Joe L.]

Re: Is this the correct dated block for my car?

Many engines were within a week or two from casting to the installation in a car, but there are a lot of variables involved. Configuration (base engines move a lot faster than odd-ball combinations) last in-first out practices at the engine assembly plant, and assembly plant, and other things. When we first wrote the midyear judging manuals back in the early 80's, we tried to reach a happy medium that would not exclude an original car that was a genuine outlier, and also allow some latitude for an owner faced with the purchase of parts for a true "restoration" Looks like we maybe didn't due too badly some almost 30 years ago.

Bill------


I remember very well something that the late Phil Hawkins and George Barlos who worked at the St. Louis Corvette plant for many years used to say. They said "we weren't in the grocery business so we didn't rotate our stock". It was last in, first out. It was consequently easy for an engine to get stuck in the back of the engine bay and not be drawn out until the end of the model year when the factory was trying to use up existing inventory of components specific to the model year (e.g. engines).

[Roger G.]

Re: Is this the correct dated block for my car?

I have to ask out of curiousity, did the casting dates on the heads and intake typically fall within a short time frame from the block? I'm wondering if the OP has the original heads and intake, could the casting dates provide a clue as to what the casting date of the block may have been?

I have to agree, if NCRS flight judging rules allow for up to 6 months, anything closer to what may have been the casting date of the original block won't buy the owner anything. Still not the original.

[Joe L.]

Re: Is this the correct dated block for my car?

I have to ask out of curiousity, did the casting dates on the heads and intake typically fall within a short time frame from the block? I'm wondering if the OP has the original heads and intake, could the casting dates provide a clue as to what the casting date of the block may have been?

Roger------


The answer to this question is "more often than not, the heads and intake manifold will have casting dates close to the block's". However, this is not hard-and-fast and big blocks are the engines that most often evidence discrepancies in this "rule-of-thumb"