I am trying to make a code correct motor for my 1968 400 HO convertible. It was made first week of January 1968. I have a WQ coded block. Its in storage but I think it is a October/November 67. I know most of the engine parts are carried over from 1967 for early 1968 cars but what is too early for date coding? Does it matter if all the engine parts are over a 2-3 month range? I just got a December intake manifold (which I think should be no issue). and have my eye on some October heads. Is October too early for this car? Am I over thinking it?
Thanks in advance

HI,

400 HO did not arrive until the 1968 model year. The HO for 67 was a 67 326 HO.
Here is a list of 400 WQ blocks. Check your block casting to identify which year.

Year Engine HP Engine code Trans CR Cam Head Code BBL Carb No. Misc
1967 400 325 HP WQ M 10.75 744 670 1-4 7037277 RA A.I.R. Block Casting # 9786133
1968 400 335 HP WQ M 10.75 068 16 1-4 7028271 HO Block Casting # 9790071
1969 400 335 HP WQ M 10.75 068 48 1-4 7028273/7029273 RA III Block Casting # 9790071/9792506

The actual motor for the car as identified in the PHS docs is where the real money is. Do you have any idea where the old one is?

If you cannot get the right one then period correct is the next best thing. The car will be worth more than a 400 car but less than a 400 HO (numbers matching).

IMO

My block is good 400. Ho was available all 1968 mine was early in model year. Block was made in 67. When you have a week one January 1968 car the parts are used from the 1967 year. My question was how big a Span is acceptable from 1967.

About three weeks.

The block I got is a nov 27 build. The car has a build date of January 3. So a month. What would be the earliest assemble date for a 68 model. Do they have pre December 67 build for 68 model

I'm really not sure what your question is, but '68 model year cars started construction the first week of September '67. Oh, and my '68 coupe's build date is also Jan 3 of 1968. What a coincidence.

I have a matching 68 ho. I believe Gus68 is right. Should have the 68 block numbers not 67. Someone might have stuck a 67 block in along time ago or recently thinking the buyer would not notice the difference except that its a ho. WQ car. All the other parts should be a few weeks or so before the build of the block.

If you have a week one JAnuary 1968 car how could you have block stamped made in 1968? From what I have read many 1968 cars have 67 stamped parts as the stamp is the date they were made not the model year they would go on. 2015 vehicles came out in 2014, the parts for them were made in 2014. Same thing was happening 50 years ago.

Am i making this up? I don't know, it is just what I have read. I am no expert but without a time machine where do the parts come from?
Are the stamped dates the date they were manufactured? They have to be why would the include the week? I got to think I am right. Heads I have been looking at from franks Pontiac parts are dated J067, they are for a 1968 HO. Not a 1967 car.
Looking for someone to say otherwise. Because then they are just making it up.

They started making parts for a model year the previous October. So a block or head with numbers for 1968 could have "J" month (october) 1967 date codes.

My 68 was built sept 67. It has mostly H ( August ) 67 stampings. Some parts did not us a i because it looks like a 1 so September will be J. My flex fan is J67

68 parts were starting to be built in July 67.

Great Harold thanks, this is what I thought. Now I just need to know from those 67 parts a definitive range of date codes. Again in my case building a coded non numbers match engine not sure how much it will matter, but I would like it to be close before I spend $7000 on an engine.
I got to think those parts are in a pile and some guy just yanks one and starts bolting it together, I have seen articles talking about as much a 3 month range of date codes on a matching motor. Anyone with matching motor have a big range of date codes, I would appreciate any responses, from exact matching date codes to the biggest variety

Thanks in advance

3 months is a little much, dated parts should be closer to your build. I've always been told no more then a month to 6 weeks.

Just curios, for the build date are you guys using the code on the data plat on the firewall or the invoice date or something else? Neill

Build date on the data plate would be the build date. Invoice date could happen much later depending on the situation. Mine was only a week after the build date but I have heard some being months difference.

My convertible engine casting date is K307, intake K237, data plate 12c, and invoiced 12/28/67.
400 coupe engine A048, heads L137, exhaust man A038 data plate01b, invoiced 01/18/68. Both cars numbers matching.
If you added 3 weeks for engine components and 3 weeks between engine and body six weeks might not be completely unheard of. Hope this helps. Neill

It was built over the xmas/new years period, I assume the GM plants let their employees have a break back then.. so can allow another week or so for that.

The 2 to 3 week spread (sometimes up to 6 weeks) s a general "rule of thumb" for Firebirds build during the mid year release for 67. The 67 Firebird was released January 23rd 67. The difference in the 2 to 6 week spread between chassis build and engine components (intake, heads, block, carb, waterpump, alternator, distributor, etc) is/was due to the foundry ramping up production and having stock on hand prior to chassis build. So....complete engine assemblies, transmissions, rears were produced well before, I've heard as early as November 66. The Firebird 400 shared the same block casting, 670 heads, intake...et al of the GTO.

The spread of dates of dated chassis components depended on the power train of the Firebird. 6 Sprint 6, 326, 326 HO, 400 and 400 Ram Air.

In 68, production of engines and ALL aforementioned drive train components caught up for the 68 model year and the dates between chassis build and power train were MUCH closer. I have owned 4 numbers matching documented 400 4 speeds over the past 6 years and own 2 now. My 68 400 HO has a chassis build of 12C with all driveline components between December 13th (rear) December 15 block, December 17 heads, December 7 intake, December 24 distributor and alternator, December 18 Muncie. The oddball is the long branch manifolds K and I (November and Sept of 67) Ill get into that later...Invoice date 12/30/67

My other 400 4 speed 68 is also numbers matching with a 12D chassis build. The dates I don't have on hand but they are as close or closer than the HO. Invoice date 1/8/68. As well, the VIN numbers are 2103 apart.

HO and Ram Air specific parts will have a greater differential in casting dates. Why? Low production, model specific. This held true for the #31 Ram Air I heads and to a lesser extent M21 transmissions and 3.90-4.33 rears and 3.36 up Nodular rears.

I will post all date codes for the latter 68 later today.

To close...in 67 (and I've owned 7 or 8 of them) will have chassis components upward of 8 weeks prior to chassis build and will have drive train dates scattered all over. I had a 04D 4th week April 67 with a unmolested 400 that had a block from March, 670 heads from Feb, intake from April, carb was 2nd week April. Some birds were tight with the dates, some were not. Once you got past the ramp up of a mid year release and a 109,300 production run...the 68 had the 8 week retool and revamp from July to August to produce the chassis and drive trains in unison.

I am in Michigan too...drop me a call today and I will clear everything up for you. Need your chassis build..PHS if you have...I also have some very nice HO specific parts if you are looking.

Three one 3 574 7312.

Tom

I was mistaken on the non HO 68. It is a 01A chassis build with a 1/8/68 invoice.

As follows, the dates. L067 block, heads both L267, INTAKE L067, carb 3407, 7L14 distributor, exhaust manifolds L087 and L117, trans is P8T17 (December 17th), rear is a 3.36 nodular with a 255 date which is Sept 12th 67.

As I stated prior...the POSI N rears/heavy duty were 3.36 and up and will have a casting date much earlier than the other date coded parts. Standard rears will generally be closer to engine build. As an example, my HO has a standard 3.55 non post rear. Its date is L157 which aligns with all other engine/trans date codes which are all within 2 weeks. If I remember correctly, HD rears have a 3 digit calender date code whereas all others are the four character month/day/day/ last digit year.

As asked prior...engine components for 68 were manufactured in 67 as the model year was august to july. So, Firebirds with chassis build dates in 68...even into Jan can have 67 dated parts. There was no carryover of blocks (different casting number, heads, different casting number distributors (different casting numbers) carbs (different casting numbers.

A tidbit of insider info from my uncle who worked at GM for 42 years...with the latter part at the Willow run warehouse...was that whatever heads, blocks, intakes, distributors rears that were left over from a model year were warehouse and were NOT stamped with an EUN nor block code or VIN. These were for warranty purposes and or NOS purchase by enthusiasts.

Another tidbit...I was fortunate to meet workers from the Lordstown and Norwood plant 2 years ago. I spent the weekend there as a guest (and room mate) of Scott Settlemire (aka FBodfather) I got some really cool period correct 67-69 Firebird memorabilia from the workers. After a weekend...I got to talk to 20 to 30 line workers. A great percentage of them took GREAT pride picking individual dated components while the Birds were going down the line. Imagine men and women having a mid December 68 block trying to hunt down head and intake dates as close as possible to the rest of the drivetrain! It was also related that a small percentage of workers didn't give much detail to this endeavor of pride.

I will always cherish those discussions...they knew I was a purist and answered all my questions with pride!

AAcenho I you are piecing together an engine...

November 27th block.. from what I've seen with HO specific birds...I would shoot for a few days prior to block casting and a max of 2 weeks post for date codes for heads, intake, carb, exhaust manifolds, distributor, rear (depending on HD POSI or standard) the alternator, water pump, starter isn't that much of an issue as these are wear parts.