I googled this to death but can't find the answer. I have casting 14081045
bbc heads that are rebuilt. I want to get a pair of 336781 heads. Will the valves and springs from the 14081045 heads fit in the 336781 heads? I would like to just use the parts I have from the rebuilt heads if possible.

781s are likely 2.06 x 1.72 valves.

336781 = 2.06 x 1,72

1408104(5) 4? are the same.

http://www.nastyz28.com/bbcmenu.html

Edit... I found 14081045 on http://www.mortec.com/bbc.htm NastyZ may have a typo.

Anyway, the springs will physically fit but you need to match spring pressure to cam mfg. recommendations.

336781 = 2.06 x 1,72

1408104(5) 4? are the same.

http://www.nastyz28.com/bbcmenu.html

Edit... I found 14081045 on http://www.mortec.com/bbc.htm NastyZ may have a typo.

Anyway, the springs will physically fit but you need to match spring pressure to cam mfg. recommendations.
Weird that 14081045 aren't on that page. Do you think they're the same as 14081044? I know the mortec site has 14081045 from 1978-87.

DANGER!! 781's had 2 different installed heights, the typical 1.880ish and a shorter 1.780. I don't hang out in the head rebuilding department much any more, but a quick recollection is if the intake spring seats are deeply recessed into the head, you have the tall install height heads and most BBC springs can be made to work. If the seats end up flush with the casting roof of the head, you have the short installed height, and your spring selection became much tougher.
What's wrong with your other heads? (781's are overrated, there are several other very similar casting numbers that will work just as well, and your current heads may be one of them)

.....
What's wrong with your other heads? ....)

peanut port.

Fwiw, Mark IV cast-iron BB heads come in the following valve size heads!!

1.84"/1.66";

1.94"/1.66";

2.06"/1.72";

2.19"/1.72"

2.19"/1.84"; and finally

2.19"/1.88"..

And it took me years to finally verify the first two valve size heads existed and were used on the tall deck, 366's and such!!!

pdq67

Might be a neat idea to try your peanut port heads before going to the expense of building another set of heads, unless you're building a bunch of cubes or want to run big RPM. I could be wrong, but GM must have found some benefit to the smaller port heads since they used them in production for so many years. Low and midrange torque is a good thing. ;)

Right about the two BB valve spring installed heights!

They are 1.88" and 1.80"!!

Crane sell's two (2) inexpensive kits of "springs and retainers"!

MAKE DARN sure that you get the CORRECT parts b/c both springs AND both retainers are different between the kits b/c of the different installed heights!!

Just ask me how I know?

And use the .015" hardened steel seat/shim protectors too as well as a rotator eliminator kit if you have them on the exhausts!

pdq67