NOS GM BBC Valve P/Ns
 

Hi folks,

I have a set of 2.19"/1.88" NOS GM valves with part numbers 340286 and 340287. Each box has the GM 'special parts notice' sticker on it and the valves themselves appear to be swirl polished. Can anyone verify these part numbers - are they OTC racing valves, or just standard issue rectangle-port valves?

Thanks!

Pics:

https://photos.smugmug.com/SYc-Site/...A797D52-X2.jpg

https://photos.smugmug.com/SYc-Site/...61528E7-X2.jpg

https://photos.smugmug.com/SYc-Site/...889D854-X2.jpg

https://photos.smugmug.com/SYc-Site/...1546AC9-X2.jpg

https://photos.smugmug.com/SYc-Site/...1B11367-X2.jpg

My book has 286 as inlet and 287 as exh 396/427/454 Mark Std Stem 12.19 head titanium alloy. Larry

----So definetly high perf......Bill S

Holy cow, I had no idea these were titanium. Anyone know where these would have been used and where I ought to market them?

Short 6 digit number says late 70's,early 80's to me.
I checked all my Chevrolet Car & Truck books from 1965 to 1975,nothing.
Probably later Corvette,which I don't have books for that late.

----Wow, Tony, How did you end up with these???.....Bill S

They don’t look like Ti , see if a magnet sticks to them. Or can you weigh them? If they are Ti should be under approx 95 grams for intake, probably 70 for exhaust.

Intake may be as they appear to have coated stems.

Thanks! I'll head back to the garage tonight and try the magnet.

These were part of a package deal on some other BB stuff (mostly aftermarket parts, nothing special) that I happened to need for a build.

FWIW - Stainless is not magnetic either, I don’t know if the GM swirl polished valves are steel or Stainless, only true way is probably to weigh them or grind them, Ti gives off silvery sparks when you grind them. I can’t remember seeing a swirl polished Ti valve as they are all machined from bar stock I think.