Blues77

462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves.
and also
3927186....69-70...302/350......Camel hump,64cc chambers,accessory holes

The 462624 have blue springs on them ..would that be aftermarket? Both sets of heads have rust.
are any of these worth rebuilding and replacing my stock heads?

PatsLs1vette

i have a set of 624,s and let me tell you not a good performance head at all..and im sure others will agree...id go with the second set..small chamber 64cc

Corey_68

Why aren't they a good set of heads? There's 76cc and 2.02/1.94 valves. They are listed at the most high performance production head chevy made in iron casting. :confused:

adam

Both sets have a good use, you got a good pair.

The 186's are fine for rebuilding - a good valve job, hardened exhaust seats (if not already there), porting, etc.
The 624's are fine for practicing your porting techniques before porting the 186's. You really though only need
one to practice porting.

PatsLs1vette

if they have 2.02 valves....then ok... if they are the smaller valve ones then y waste time with them..

Smokehouse69

The 624's are lighter weight castings and prone to cracking. Go with the 186's, they are pretty good heads when rebuilt to more modern standards. Bigger valves, hardened seats, and a good port job.
They are some of the best performance Chevy made, prior to the Fastburns and Vortec heads.

GTR1999

I just posted about the 624's myself. They have 18k miles on them but I was thinking about replacing them when I do the cam.
Gary

Ganey

Thad

In the process of making the 624 lightweight heads they got irregular intake ports not good for performance.