Been reading another thread on here about C6/C8/D2 heads, and I agree with everything everyone has said, except the C8AE-H heads I did for my 390 seemed to have MORE meat for porting than a set of D2 heads I had... I wonder if it's just a toss-up which ones are better, depending on the drift in the cast-iron mold

Anyway, I have a '67 390 2bbl sitting in the corner of the garage, taken apart so I can ID everything possible (and to possibly sell it off in parts), but the heads are C7AE-A heads - 8 bolt exhaust.

Why are they different than the C6 or the C8 heads? Why only one year these heads were produced?

Just a curiousity really...
art k.

EDIT: Crap! I meant C7AE-A!!!

 

Mainly because they were playing around with the combustion chamber shape and volume for faster burn rates, lesser surface volume and more turbulance.

Here’s a typical ’66 and earlier big “D” chamber wedge head, lots of surface volume for quench but along with it comes excess hydrocarbons. Also the sharp edges collect carbon over time:


Here’s the one-year-only ’67 with a smaller rounded “D” chamber, the wedge shape is less pronounced:



Here’s the final C8/D2 jellybean chambers, intake valve is more shrouded for turbulance and mixture. These hardly have any quench and hit the piston harder than the wedge heads:

 

Sheesh... you da man...

 

I think you have the "quench" thing bass-ackwards BB------- the C8/D2 heads offer more quench, not less. Smaller chambers= more/better quench. Open chambers= less quench and are more prone to pinging.

 

Agreed. Smaller chamber is better for quench.

FWIW, I've got a set of C7AE-A's that are identical to the second picture, that I'm porting and polished the chambers. I'll take pictures when I get the first one done if anyone wants to see 'em.

 

I want to see them.

 

Baddad, you're right, I wrote that too fast before skipping out and was thinking wedge, not quench! Yes, I understand open/closed chambers, thanks for setting it straight!

The problem with our trucks is the deck height is too low for the C8/D2 heads to work, more than .060" down and the quench don't work.

Speaking of chambers, I like the ones in the old C2SE/C3SE 406 heads, they will take a lot of compression without pinging.

 

So BB, your saying that with the FE...if the piston down bore is greater than .060" the heads will not quench? I thought that stock the 360's and 390's had alot greater distance down bore. Or is that your point....? lol

 

Mis post............