# 1966 GTO heads 093 & 092



## shjensen8 (Jun 24, 2017)

Hello,

I am new to this forum and just starting on a 1966 GTO Tri Power restoration project and glad to have a resource like this to help answer some questions and help guide me along. I believed it to be numbers matching but have ran into my first issue. I just pulled the engine and it is a correct WS block with the correct date code. The block should have the 093 heads on it since it is the 360 HP engine. However, the passenger side has the 093 head stamp but the driver side head has a 092 stamped on it. This does not seem to be original in the least. Is there any way that this combo can work?

Looking forward to any insight and help that can be imparted.

Sam


----------



## PontiacJim (Dec 29, 2012)

Looking through my books, the 092 head has a 70cc combustion chamber for 10.5 compression while the 093 head has a 68cc combustion chamber for a 10.75 compression.

Theory: 
A) Pontiac installed the 092 head to us it up as it was near the end of the build date year and the "new" designed 067 head was to be introduced on the 1967 GTO models. (Would be interesting to know the build date of your car and the build dates of the heads to see if they are within a similar time frame.)

B) The dealership had a warranty claim and replaced it using the 092.

c) Some one along the way replaced it while owning the car.

.25 point compression is not a big deal. You could try and locate another 093 head, use the 092 head as is, or cc the actual combustion chamber and have your machine shop do some light grinding on the 093 to equalize the chambers to the 092 size - but, the advertised and actual chamber cc's do indeed vary and you may find that the chamber cc's of the 093 head may be the same as the 092 head.

So does it really matter compression wise? Probably not.


----------



## geeteeohguy (Feb 2, 2008)

I recently cc'd some 093 heads and they were 64cc....this can vary head-to-head..You could do a compression test on both banks and see what you have. You are running about a half a point lower CR with the 092 head. Me? I'd get another 092 or 093 head and run a matched pair.


----------



## shjensen8 (Jun 24, 2017)

Thanks the reply's. 

Pontiac Jim, here are the date code numbers on each of the heads along with the vin tag. It looks like it was built early in the year and the 92 heads were built in 65?

92 Head: 2092 K85 - Dec 8 1965
93 Head: 2093 C (or O)256 - March 25 1966
Vin Tag: 04B April - Second Week

I think that I just might go with Geeteeohguy and get me a set of one or the other. Probably the 093 since it is what should be on the WS engine.


----------



## PontiacJim (Dec 29, 2012)

Interesting - the late Dec '65 092 head. Again, could be many explanations - factory installed, dealership warranty, or owner installed. To know for sure you'd have to have the car's history from day one. If you want factory correct, yep, go with a matched set of the 093's. 

Just for fun, I would check the cc's on one of the chambers on the 092 head and one on the 093 head just for comparison sake. I read that .0061" milled off a head for the '65-'67 closed chamber heads (.005" for '68-'70 open chamber heads) will reduce the chamber by 1cc. My thinking is that if a light cut were milled off the 092 head, it might match the 093 chamber size. Understand you are going with the 093 for correctness, but would be interesting to compare. :thumbsup:


----------

