hey folks, was the C head available with the two ribs on the ends of the heads like a D and F head? Because Im thinking the two rib C head was a 68-69 toronado head? am I crazy?

 

I have seen them with and with out the ribs. There are no notes that I know of giving them any kind of specific application though. I believe it's just one of those production thing where parts of the core boxes transferred from year to year and nothing was tossed out if it was good enough to run production with.

 

i found outthey were A heads with two ribs off a 425 motor. go figure.

 

I don't want to high jack your thread but this also relates to the C head. I have seen C heads with a small oval heat riser passage and ones with a much larger square heat riser opening.
Thoughts insight on this matter?

 

seems different foundries all over NA seemed to throw stuff together at different times eah?

 

I've come across several sets of the small openings, but only on C heads and I believe they were all 1967's with the application stamp in the end of the head.

John

 

My collection of C head cores has been about 50/50 over the years or big/small crossover ports. The small port heads have more meat in them for porting.

 

And yet, that didn't stop you...

 

if i felt u highjacked my thread{being the thread originator} i would have said something- your post spread more light on the topic- good job. thanks guys

 

All heads were cast at GM's central foundry. Just as the blocks were. Thus the CFD markings you find on them.

 

ok that makes sense finacially

 

We pulled the heads off a 400 G about a week ago that came in a 68/69 Visa, It had small oval heat riser passages. I picked up a 425 about a month back out of a 1967 88 it also had small oval heat riser.
So they made it onto some 68's engines as well, the owner of the engine thought it came out of a 69 so they might also be found on some 69 engines?

If the passage is smaller on the oval heat riser C head is there a gain in hp V larger square shaped heat riser both heads stock untouched?

 

Untouched there is no difference HP wise. Still the same intake runner cores.