M 305 date code on 1975 333882 cylinder head

[Patrick H.]

Re: M 305 date code on 1975 333882 cylinder head

I can't recall and the T-shirt pile is way too tall. Lol. Besides a T-shirt from 1993 would no longer fit me. Time for a T-shirt quilt.

Stay safe.

My mother-in-law is making me a quilt from them because the old ones are too large.

[Paul B.]

Re: M 305 date code on 1975 333882 cylinder head

My guess is that the V he saw was part of an M.

That said, WTF was he doing looking at cylinder head dates? We don't do that, and both of you should have known that. Neither of you are rookies.

...I was a "rookie" in '96, the year my car was judged there at Carlisle and I think that was the year I became an NCRS member. I did not start judging until '98 @ the Windsor Ontario, CA Regional Meet.

[Paul B.]

Re: M 305 date code on 1975 333882 cylinder head

Well if that was the case its crazy to have a judging demonstration with pulling off valve covers.

...the valve covers were not pulled, he just happen to look under the oil fill cap and saw the date code with the "V".

[Kenneth B.]

Re: M 305 date code on 1975 333882 cylinder head

...the valve covers were not pulled, he just happen to look under the oil fill cap and saw the date code with the "V".

They cant do that either. Also judges are not supposed to take anything off & as far as I know its not judged.

[Terry M.]

Re: M 305 date code on 1975 333882 cylinder head

They cant do that either. Also judges are not supposed to take anything off & as far as I know its not judged.

You are right on Ken. I had assUmed the number was seen through the oil fill cap as Paul stated.

If this date information was done for "research purposes" or for "discussion" all is good. But if points were taken for this (which I assUmed) ... Well that is what got me fired up.

[Bob B.]

Re: M 305 date code on 1975 333882 cylinder head

Attached is a photo of the intake manifold on my '70 Convertible 300hp MIMG_0342.jpg C23 build date Bob SoCal

[Terry M.]

Re: M 305 date code on 1975 333882 cylinder head

Attached is a photo of the intake manifold on my '70 Convertible 300hp M[ATTACH=CONFIG]99635[/ATTACH] C23 build date Bob SoCal

Bob
Your intake is even more curious because on cylinder cases with the M code the letter M is usually followed by two numbers, so it in no way resembles a date. Your intake, however, resembles a partial date. Curious!!

Now we are back to Tom's original post and question.

[Terry M.]

Re: M 305 date code on 1975 333882 cylinder head

...I was a "rookie" in '96, the year my car was judged there at Carlisle and I think that was the year I became an NCRS member. I did not start judging until '98 @ the Windsor Ontario, CA Regional Meet.

Paul. Sorry I thought you were around earlier than that. Or maybe 1996 seems longer ago to me than it is. I guess I have not been preaching as long as I thought.

It may be that events such as you described lead to the need for the Advanced Judging Seminars.

I am pretty sure in 1996 I was National Team Leader for 1970-72, so I should have stopped Ed. As often happens hindsight is 20/20.

[Tom R.]

Re: M 305 date code on 1975 333882 cylinder head

Given this description is in the 70-72, 73-74 and about to be incorporated into the 75-77 revised TIMJGs, given some tweaks, it would appear there should be consensus on what these alphanumeric sequences mean. David's comment states the M is the designation for the Lansing plant, in conflict with the statement with TIMJGs. Likewise others, (above) show other letters in the casting, in the location where the date code is typically cast.

That's the intent of the original post. The purpose is to provide Restorer Guidance rather than Judging Guidance. We all know that judging twenty years ago is different, or rather should be, than it is today. Maybe its 25 years...I'm not counting.

[Terry M.]

Re: M 305 date code on 1975 333882 cylinder head

Just for the group's edification there was a story in The Restorer regarding the M-coded cylinder cases. That article contained reprints of the letters returned by Chevrolet and Saginaw Foundry to inquiries about this feature.

My understanding is that small block heads that were to be used on Saginaw cast cylinder cases were also cast at Saginaw. Off course there are exceptions in that we have identified cylinder cases cast at Tonawanda that were used in Flint Engine Assembly, and some of those were installed in Corvettes. I suppose a similar process could have happened with heads cast at locations other than Saginaw.

The more we learn; the less we know. And we don't know what we don't know.

[Kenneth B.]

Re: M 305 date code on 1975 333882 cylinder head

I was in the foundry/pattern business for almost 50years & I guarantee that is a date code not a Foundry logo. Letters/# were solderted on a steel tag drilled & counter sunk for 2 sloted screws. They had a set that was changed every day or should have been. I assume that maybe some days it might not get changed but not offten. If there was a problem they needed to know what day & shift there was a problem so they could sort out the bad castings.

[Tom R.]

Re: M 305 date code on 1975 333882 cylinder head

Ken this is helpful...For the sake of clarification, what you write has two interpretations is it 1. or is it 2. or 3.?

1. I was in the foundry/pattern business for almost 50 years & I guarantee that it is a date code and not a Foundry logo; or
2. I was in the foundry/pattern business for almost 50 years & I guarantee that it is a date code and not a Foundry (plant) logo; or
3. I was in the foundry/pattern business for almost 50 years & I guarantee a date code is not a foundry logo.

Letters/# were soldered on a steel tag drilled & counter sunk for 2 slotted screws. They had a set that was changed every day or should have been. I assume that maybe some days it might not get changed but not often. If there was a problem they needed to know what day & shift there was a problem so they could sort out the bad castings.

This statement suggests that it was a date code to track a day of bad castings, so they could be retrieved and destroyed. This makes sense, but then how to interpret what M 305 means?

[David B.]

Re: M 305 date code on 1975 333882 cylinder head

K = October
L = November
M = December
M305 = December 30 1975

[Patrick B.]

Re: M 305 date code on 1975 333882 cylinder head

K = October
L = November
M = December
M305 = December 30 1975

[Paul B.]

Re: M 305 date code on 1975 333882 cylinder head

K = October
L = November
M = December
M305 = December 30 1975

...I don't know the build date of the car with the pictured head, but if the last 1975 Corvette was built on August 8, 1975, how could it have a December 1975 dated head? Last time I checked, August was four months BEFORE December.