452 Vs. 906 CC's

[DoubleDlover]

Does anyone know the CC size on the 906 head Vs the 452?? thanks r

[Challenger340]

same, roughly 86-88 cc's

[Kern Dog]

Both are all over the map.
In 2019 I checked 4 heads. A 346, a 452 and 2 different 906 heads. I came up with different numbers but any of them could have been surface milled.
The 906s were right at 90 ccs. The others were between 88 and 89.

[DoubleDlover]

Well thats interesting. Both are pretty close. 452's have the harden seats. Better for unleaded. Interesting.

[John_Kunkel]

I came up with different numbers but any of them could have been surface milled.

To know if the head has been milled, mic the outer head bolt boss...it should be exactly 1".

Unmilled that I've checked were 88-90 cc's.

[Mike DC]

    
It's been said that all the open-chamber heads (906, 452, 346) were probably designed to have the same CC size.  The differences are down to tooling/casting variations.

 

[Nacho-RT74]

My 452s came out at 90-92 ccs

[BSB67]

Not that it particularly matters, but factory original 906 cc verses what they will measure today are likely two different things.  Back in the day, 86-88.  Today 88-92. 

[Kern Dog]

How can that be? More volume as they get older?
I'd say the opposite. Surface milling during a rebuild would result in less volume. How many times have these engines been rebuilt in 40-50 years?

[metallicareload99]

Valves sinking. Although, it depends ultimately on what's done during rebuilding (over sized valves, new seats, surfacing etc.)

[Nacho-RT74]

I'm talking about a NOS set I got.

[John_Kunkel]

The point is, these heads were advertised as having 79.5-82.0 cc chambers and they aren't anywhere near that when brand new. So much for production tolerances.  

[DoubleDlover]

And what about those 213 heads? I think thats the number. Around 73's ??

[Nacho-RT74]

Mostly are the same