I recently purchased a 67 326 HO bird. With the bird came copies of all the original papers, including the name of the woman who bought the car new. She recently passed away, but I've been in contact with her brother,
He told me that about a year after she bought the car there was a main seal leak and she brought the car back to the dealer for service, and it was then that the dealer told her that her motor was a 350.(which wasn't even offered until 68) Apparently the plant put a 350 in the car, I have a 350 in my car. Is it the original? How would I know?
So I took the car to the local Pontiac nut and he said there is no way of knowing. So I sent away for my car packet through PHS, which turned up empty, because they think I have a 326. Which according to my VIN and cowl plate I do.
Now what do I do?How can tell.

Look for the engine code stamped on the right side of the front of the block.

http://www.teufert.net/identify/identify.htm

https://firstgenfirebird.org/1967-info/19...er-information/

Yes, for 1967 the paperwork and the original engine have matching Engine Unit Numbers, not partial VINs. So there is a way to verify.

But in a nutshell, if you have a 350 Pontiac engine in a '67, you do not have your original engine due to the fact you stated above - Pontiac did not install 350's until the 1968 Model year.

But actually the story about the engine replacement makes perfect sense. The car is brought in under warranty and the dealer determined it would easier to just replace the engine. So they go back to Pontiac for a complete new replacement. But Pontiac is now producing the 350 (it's now 1968) and not the 326, so that's what the dealer installs.

In essence you got a factory service replacement engine of a different size. It will be a very interesting car show story if you have the paperwork to back it up.

Interesting, but surprizing... Most auto manufacturers have replacement parts for at least 10 years, so I wonder why they didn't have any 326's in stock? Perhaps the 326 was on back-order and they didn't want to wait?
Back then they probably didn't consider value of a number or code matching car.

You need to stop listening to the local Pontiac nut. Like Jim said, check the two letter code on the front of the block and the casting number on a pad behind the passenger side head (or near the distributor if it's an early 67 block). You will be able to tell exactly what the engine is.

ok so the 2 letters on the front are WF and that code means 400. I haven't found the other number yet.

That's what my brother said

According to her brother The engine was not replaced. They repaired it and that's when they found out it was a 350

WF is also a 73 350. So you need the casting number to make sure. Hopefully it turns out to be a 67 400. I had an early 67 400 block that had the casting number near the distributor. Later 67 blocks and later years the casting number is wy back near the firewall on the passenger side. Tricky to get to but you can stick a camera back in there and see if you can get a photo.

Thanks Bob, now I just have to locate the casting number.
That's funny you said 73, her brother said she had work done to the body in 73, but no mention of an engine replacement. I'll have to ask him.

According to Wallace a WF engine could be one of 4 engines:

Year Engine HP Engine code Trans CR Cam Head Code BBL Carb No. Misc
1965 389 338 HP WF M 10.75 066 77 / 9778777 3-2 (F)7025178 (C)7025175 (R)7025179 Block Casting # 9778789 Should have full head production number under valve cover - 9778777
1967 400 350 HP WF A 10.5 066 670 1-4 4242S GP A/C Block Casting # 9786133
1969 428 370 HP WF M 10.5 067 62 1-4 7029263 GP Block Casting # 9792968
1973 350 150/175 HP WF A * 7.6 555 46 1-2 7043062/63/72 Block Casting # 488986; * shows auto in service manual?



http://www.wallaceracing.com/cgi-bin/engine3.cgi

Check for the head code. It's on the center exhaust manifold. Possible head codes: 77, 670, 62 or 46