TBI Exhaust Valves, cast stems?

[PlayingWithTBI]

There is a Nice but shallow blend cut in the Combustion chamber, then the 45 degre seat cut, so far so god.... THEN, there is a deeeeep 90-ish degree cut creating a sharp step, before an even deeeeeper throat cut into a throat that is about 1.6" in diameter...

Wow! I never bothered looking at my old 193 head valves. As an example, here's what my Summit Racing aluminum heads (2.02/1.60) look like.

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And the new SS valves.

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[1990Z71Swede]

Well on the bright side, potential for improvement is large and easy to see.

All it needs is a throat that matches the valve, and a proper 60 degree throat cut after the seat. Oh, and maybe NOT a knife edged short turn

But...on the not so bright side, it might take going to 2.02 valves to clean up the "plunge cut" that GM made. I'm not sure if the seat hardening is wide/ deep enough to go that route?

 

[tayto]

Well on the bright side, potential for improvement is large and easy to see.

All it needs is a throat that matches the valve, and a proper 60 degree throat cut after the seat. Oh, and maybe NOT a knife edged short turn

But...on the not so bright side, it might take going to 2.02 valves to clean up the "plunge cut" that GM made. I'm not sure if the seat hardening is wide/ deep enough to go that route?

pocket porting blends/removes this ledge out

 

[1990Z71Swede]

What valve/ throat ratio do you end up with? I'm reluctant to go further than throat being 90% of inlet valve. For exhaust IDK less severe of a ledge there, and seat is pretty wide I might get away with moving seat out a little bit on the Valve and narrowing the seat slightly to make room for a 60 degree throat entry cut.

I' ve been staring at the intake ports for a good 30 minutes trying to figure our what to do with them, they are sooo weird...

 

[tayto]

stock valves, get out the die grinder

 

[1990Z71Swede]

Do you have a picture like the exh one above but of the inlet?

 

[1990Z71Swede]

I finally figured out what way I wanted to go with this. Opened upp the throats to 83% as a start, very simple to do and takes maybe 20 minutes per head.

Next I'm bringing it over to someone that knows what they are doing to see if the seats can cut like I want them without sinking the valves deep in the head.

This is where I'm at right now.