# '67 GTO engine code mystery



## Bluesbrother (Oct 4, 2010)

OK guys...I have a couple quick questions I hope someone can answer and help me clear up. First off, I have decoded my VIN tag and it seems I have an early (I mean EARLY) run '67 GTO convertable...number 863 off the Pontiac, MI assembly line....does this mean the 863rd "GTO" or the whole GTO, Tempest, Lemans line?? I am in the process of a frame off restoration and want to be sure everything is correct to the best of my knowlege. It was also ordered in "Code M" Plum metallic which makes it a kinda odd car...but differant than a lot of them.

OK...here's the mystery. After checking all the date codes on the motor (the car was purchased in 1973 from the original owner) they all seem to jive with the early run with parts dating back all the way to March of '66 (from what I have researched, the actual "number matching" codes were not stamped in the run until late '67??) I have searched many, many sites for info and the engine code on the block does not match any known number in the GTO books or Pontiac documentation. After getting my PHS documentation, 'lo and behold, there was the SAME number on the info from PHS.

Does anyone have any idea where this 400 block came from....heres the number stamp code...

181885 (it's a 335 HP YS motor...I do know that)

I have been told it may be a "leftover" early test block, but that info is a little sketchy. Here's another little tidbit that made me smile too....It was delivered to (of all places) Royal Pontiac in Royal Oak, MI (GM's underground Pontiac Speed Shop....LOL) so it has been in Michigan all of it's life and is in awesome condition with all of it's original sheet metal and parts intact. 

Any help from you guys would be deeply appreciated!!

(I attached a pic of the documentation on it)


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## PontiacJim (Dec 29, 2012)

A 1966 block would only have 2 freeze plugs on each side of the block. 1967 and up have three. On the block near the distributor hole is the date code. The first letter is the month, A=January, B=February, etc. Th next two/three digits are the day with the last digit being the year 6=1966, 7=1967, etc.. Production cars begin the new year in August. If your block was cast between August-December of the previous year model, here being yours is 1967, then it would have the 1966 date code August through December, or Month codes H,I,J,K,L. If it does, then it is correct. 

YS is for a 335HP, automatic, "670" heads (cast on center exhaust port), carb ID #7027262. It is a 1967 GTO engine. The 335HP engine appears to be the same as the 360HP engine except it used the "067" camshaft versus the 360HP "068" camshaft. 

I do not feel it is some experimental block left over, its factory for your year. Royal Pontiac was a Pontiac dealer that offered the Royal Bobcat upgrades as an option to your GTO, or other Pontiac.


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## geeteeohguy (Feb 2, 2008)

Early '67 GTO's would not have early '66 parts on it...not March of '66. My '67 GTO is an early car, made in Sept. '66 (or was it December?) and has no parts earlier than 9/66 on it. As Jim said, you need the date code and the casting number. The 'experimental block 'theory is about as likely as an honest politician.


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## 05GTO (Oct 6, 2004)

Bluesbrother said:


> Does anyone have any idea where this 400 block came from....heres the number stamp code...
> 
> 181885 (it's a 335 HP YS motor...I do know that)


You have a numbers matching YS block, I mean that engine is the original engine that was born with your 67 GTO.

Starting in early 67 Pontiac Identified their engines with the engine unit number, mid year they added the vehicle vin number to the block.


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## Bluesbrother (Oct 4, 2010)

OK guys....some GREAT information from all of you so far!!! Here is what I got as far as codes off the block and heads:

Block: B6138 and under that is a cast code of L046 (the "B" may be an "8" or a "3" as it is cast right into the side of a screw plug) 

670 heads are cast with these codes:

K216 (passenger side)
J086 (drivers side)

I can tell you this...this car was purchased from the original owner and was a friend of my father's. He purchased this car because he knew it had never been in an accident or had any major mechanical work done to it. As I have started this project I have found several things that are differant than the others I have seen. My cowl is painted original purple to the seamseal line, and I have been told this wasn't done, but there it is painted and we know there was no paint work done to it. When we rebuilt the motor, we noticed "locking" allen screw bolts on the rocker arms, and noticably thin head gaskets (they were like paper thin!!) and the heat risers were blocked off...again, we know that no one did any major work to it...so it seemed weird??? Any thoughts??


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## SCG Pontiac (Feb 23, 2014)

Something to look for. First of all sounds like a great car 67 plum mist would be enough and delivered to Royal even better. We have a very rare GTO in our collection at Surf City Garage. It is fully documented and Jim at PHS helped a bunch. The car has been written about in various media. It is a 71 GTO Judge pilot car ser. # 0000016 that body tag number is not just the GTO line it is for the Pontiac Motor division. This car was built on April 17th 1970. Under the back seat is a PMD engineering document stating PILOT 16 . The fuel tank has a big sticker on top with the original build sheet that says Buick. They used various parts to mock-up their production line for the coming year. The engine is a 1970 455 GTO and like your car it is listed on the documents. Many other odd things about it and we spent two years researching the car. Most piolt cars were crushed but not all. This car was delivered in Septemper 1970 to a dealer in Dallas Texas. Another funny thing on the invoice for the car it lists Pontiac Engineering as the seller. You should gently pull some interior parts out to see what you can find, start with the back seat. Good Luck and have fun with it.


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## 05GTO (Oct 6, 2004)

Bluesbrother said:


> OK guys....some GREAT information from all of you so far!!! Here is what I got as far as codes off the block and heads:
> 
> Block: B6138  Casting number for 67 is 9786133 (some blocks did not have the full casting number because of lack of space), and under that is a cast code of L046 Date code may be November 4, 1966 or December 4, 1966, If I remember Pontiac didn't use the letter "I" for 67 date codes(the "B" may be an "8" or a "3" as it is cast right into the side of a screw plug)
> 
> ...


All of your codes seem correct,


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## geeteeohguy (Feb 2, 2008)

My Baltimore '67 has body color on the firewall to the seam seal line and beyond, underneath the semi-flat black paint. I have seen a few GTO's over the years that were body color and not painted over on the top half of the firewall as you describe. Your engine sounds like it may have been 'Bobcatted" by Royal or with a Royal kit. Looking better all the time!! Pics, please....


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## Instg8ter (Sep 28, 2010)

The thin head gasket was part of the dealer mods that Royal did, sounds like it has been "bobcatted"

The precise components of the kit varied but generally included pieces to modify the spark advance of the distributor, limiting spark advance to 34-36° at no more than 3,000 rpm (advancing the timing at high rpm for increased power), a thinner copper head gasket to raise compression to about 11.23:1, special intake manifold gaskets to block the heat riser to the carburetor (keeping it cooler), larger carburetor jets, and locking rocker nuts to hold the hydraulic valve lifters at their maximum point of adjustment, allowing the engine to rev higher without "floating" the valves. Properly installed, the kit could add between 30 and 50 horsepower (20-40 kW), although it required high-octane superpremium gasoline of over 100 octane to avoid spark knock with the higher compression and advanced timing.


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