Bernhard

Factory service replacement heads?

Are they rare?

What do they sell for?

413191 head number

joe_padavano

Those are K and KA castings. Used in marine and industrial applications in the 1970s, and used to supercede all the performance BBO heads in the parts system. The fact that these castings superceded the D and F heads DOESN'T mean that they are just as good. All it means is that these were the best available replacement head in the parts network at the time. They are certainly better than J heads, which were the only other castings available by the mid-1970s. Going rate is about the same as for C heads.

dnmfranco

Bernhard, they are available. A couple sets just sold on ebay for a 100 or so a head due to needing valve jobs. I have a set completely done maybe selling in order to go back to c heads.

Bernhard

Thanks for the reply's

Very good info I just read that they were service replacement heads listed by the NHRA.
Wanted to know if they were as good as a D or F or C
I will be using C heads on my engine to start,would have liked to try D heads but the buy in cost high.If the engine works well I might spring for some later on.

I was reading the specs on the standard 442 valve springs they were rather weak compared to the H/O spring only 84 closed 194 open

Compared to the H/O 125 closed 308 open

Still looking for the W 30 and W31 valve spring specs for 68/69
I have to find my 69 service manual or buy a new one again.

Octania

K's are always big valve heads

they command a good price because they are legitimate acknowledged replacements for D, F, H heads, but far more readily available. Try to find some H castings. Yeah.

joe_padavano

I wouldn't place too much stock in the "legitimate acknowledged replacements" thing.

As I noted, the factory listed them as superseding the performance heads when J and K castings were the only ones available in the parts network. That same parts book shows J castings as the "legitimate, acknowledged replacements" for C and E heads, for example. Are K heads better than J heads? Sure, and they are probably as good as any other BBO head. That doesn't exactly make them special or worth a lot of money. Keep in mind that the fact that NHRA accepts them as replacements for F heads only means that they do not provide a performance advantage over F heads in Stock classes.

lemoldsnut

I have wondered for some time what is the difference other than casting number and letter between the bbo heads, so many have the same reported camber size and valves. maybe those who are in the know can enlighten me.

Thanks in advance for your knowledge.

What I mean is mainly the diffence between the following heads,
A
B
C
D
E
H
K

not G or J

Bernhard

There is a flow difference between the same letter head just in the way the head was cast.
Is it large no but racers used to look for it..
They did the same for intakes.
From Bill's book J's are junk and E heads were smaller by a few cc.
But again could that be down to a poor casting of that version.
From what I have read they all seem to be close.
The D heads have a nice comp bump over the rest.
Bill also said that A heads look to be the best as cast.

Only way one would know is to test and that's just to expensive and time consuming.

I going to stick with my C heads as that is what came with the car, I might try and find a A head just as a reference.

joe_padavano

^^^^^This.

I've seen published lists of stock flow rates, but I find it hard to believe those lists are based on more that one or two samples of each. Manufacturing tolerances alone will account for the differences. J heads aside, all BBO heads flow about the same within manufacturing and test tolerances. And with the exception of the ~72cc chambers on the D heads, all BBO heads have about 80-ish chambers. Again, this will vary +/- a couple of ccs from head to head just due to core shift, valve seat machining, etc.

lemoldsnut

I have been under the impression that what Joe just said is how it is. Pretty much the same basic heads. Hum interesting.

Fun71

Which makes me wonder why the G heads are excluded here:

Bernhard

Stock head flow numbers
http://nichibei.tripod.com/headflow.htm