V6 Cylinder Head Emissions Ports

I have a question about the so-called emissions ports in the Dauntless V6 cylinder heads. I'd previously thought that these ports were present on the later V6's, as opposed to the early ones. However, when I posted these photos yesterday Factory Engine Bay Photos?, I noticed that this very original unmolested V6 (with less than 3k miles on it) that dates from late 1965 has these port plugs.

Apparently all the Dauntless heads had them - but 1965 was several years before emission control measures were required on American cars. These ports were probably a hold-over from Buick's early 1960's design, but why would emissions ports have been present at such an early time frame?

 

I believe there are some early Dauntless heads without having those ports.

 

My 1965 buick 225 odd fire v6 skylark engine does not have them

 

Interesting...then evidently the emissions ports were not a carry-over from the Buick design. And it sounds like there's evidence that the earliest Dauntless heads didn't have the ports either.

But if they had no apparent use until years later, why would the ports have been cast into the heads of the early '66 Dauntlesses (like the one in the photos linked to in my first post above, which was built in Oct. '65)?

 

I had a '67 Jeepster that did not have those ports. The next time I get up to NC I will get some pictures of the heads.
-Donny

 

California was the first place in the world to regulate vehicle exhaust emissions. Air injection was mandated for all California passenger vehicles with manual transmissions in the 1966 model yr. which would begin in sept 1965

 

Smog pumps started on the 1966 model year in California so a vehicle built in late 1965 could have had the heads installed simply because that what was available at the time or it may have been built as a California vehicle that never made it there.

 

No emissions ports on Farm Jeep Willy or the spare heads in the shed if that adds to the discussion.

 

This is no doubt the reason the emissions ports came into being during that particular time frame.

Thank you for solving this little mystery!

 

Lower compression did become part of the solution but not instill the 1971 model yr when NOX regulation took hold and new head design lowered compression significantly

 

I believe the lower compression ratio is because of the design of the piston (dished vs flat top) rather then the head design .That came about with the redesign of the 225 to the reintroduced GM 231 engine

 

Is that the difference?. Dished pistons gave a larger displacement number?

 

No, dish pistons don't increase displacement. Bore x stroke x # cylinders = displacement.
Most 225 odd-fires have dished pistons, some more dished than others to lower compression ratio. There may have been a Buick verient that had flat top pistons.
The 231 standardized bore sizes with Buick's V8s so they could share parts, increasing displacement in the process.
-Donny