Difference between C5 and C6 log head

[amartin83]

It appears to me through research the only difference is the addition of cast bosses on the exhaust ports for the thermactor (emissions air pump)on the C6 head. Is that true? Is there anything else?

-Aaron

 

[CZLN6]

Howdy Back Aaron:

The C6 head casting could either have the bosses for injecting air into the exhaust port, or not. Most C6 heads do not have these taps. To the best of my knowledge the Thermactic Air pump was a '66 -'69 Calif. emissions requirement. C/E engines also had lower compression then the rest of the US. But they accomplished this with a larger dish in the piston tops. Other than the exhaust port taps the two castings appear to be identical.

Hope that helps.

Adios, David