Hi Robert

Yes the intake and exhaust valves were the same size and in fact the same valve in 1929 sixes, but only in 1929.

I'm not sure what the diameter was.

Yes the original valves had rectangular holes/slots in them for the keepers, but...

that wasn't one of Chevrolet's better ideas and was prone to failure.

That weakness was corrected a few years later.

So, modern replacement valves will likely use modern keepers and caps.

According to Filling station, these are the data for 1929 valves:

Manufacturer's Part#: 835583
Head Diameter (inches): 1.40625
Length (margin to tip): 4.02593361
Stem Diameter (inches): 0.31
Seat Angle: 45

1929 valves at Filling Station

@morten-c 

Hi Morten

I was looking for some actual Chevrolet data to verify what the Filling Station had listed.

I found it.

From the 1929-32 Master Parts book, they were 1-13/32 inches in diameter, which is 1.406 inches, the same as the FS specification.

Thanks for the replies. The 6 NOS valves I received are 13/32. The 12 valves I received from another source are larger and will re returned.

I really appreciate the help. I hope to have the engine pulled this week.

Is it possible valves we're made larger after 1929?

@robert-loer 

Hi Robert

Short answer... yes.

The intake valves were made larger the very next year, 1930.

The exhaust valves were however made smaller at the same time.

The engine then "breathed" better, which made it a little zippier with a little more power.

Thanks for the info. I suspected something like that