Technical Shrouded intake valve sbc iron heads

I recently dug out a couple pair of old cast iron chevy cylinder heads from the 60's and noticed a big difference in the combustion chambers. Each of these sets (3890462 and 3917291) have 2.02 intake valves but one set have been unshrouded around the intake valve. Was this machine work done by chevrolet or an outside machinist? I'm told the 2.02 heads were unshrouded when they were new and the 1.94 heads were not. I've not seen a picture of Chevrolets unshrouding to compare to what I have. Anyone have a pic or can help me out on this little detail? The first 3 pics are the 462 heads while the bottom is a 291 chamber with no unshrouding.

 

Were these kept in a clean room for 60 years? Looks a lil fresher to me.......

 

That was done by a outside shop,judging by the job it looks very well done.
I would have to see it with a intake and a ex removed to really tell how well.

 

The 462's look like fresh machining, but is exactly what Chevy would have done. The 291's have just had bigger valves installed. I think Chevy used a 2-3/16" cutter to unshroud the valve.

 

Yea, both pair were done by someone a few years ago, I'm just now getting the top of the motor together. I think I'll do very minor blending inside the bowl and go with it. Would still like to see a pair with original chevy shrouding.

 

I think you'd be hard pressed to tell the difference. JMHO.

 

No...that's a big, nicely done difference.
30tudor needs to make sure that the diameter does not overhang whatever bore size that his block (or the gasket) has.

Mike

 

Them heads are beautiful!!!!!......