810 cylinder heads.

[Schurkey]

Hardened Exhaust Valve Seat insert.
I think @Schurkey said in another thread of mine that he had never seen a chevy head with a single angle valve job. Well, here is one

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Wow, that's ugly.

Pushrod holes, round on 810, slotted on 193

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Round holes and no pushrod guideplates = self-aligning rocker arms.

Slotted holes--assuming they're a close side-to-side fit on the pushrod = regular, NOT self-aligning rocker arms.

193 Head. With Ugly Bowl hog step, making it very difficult to do a proper valve job, without sinking the valve deeeep in the head.

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That "bowl hog" cut--is that a fuel-shearing "step" under the valve seat?

 

[1990Z71Swede]

That "bowl hog" cut--is that a fuel-shearing "step" under the valve seat

For a while I was sorta thinking along those lines as well, and I guess it will do that too. But I believe it's not the primary reason for it as the exhaust has a very similar step.

It's cut like that because it's the simplest quick and dirty way for the factory to get the seat width correct, me thinks.

And after all that Heatin' and Swirlin' one would hope there's not much fuel left needing Shearin' anyways

193 Head:

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[1990Z71Swede]

Is the Exhaust valve in the 810 really that heavy?

Well it is 9,5% heavier than the 193 valve.

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[1990Z71Swede]

Never in a million years would I have thunk that I would dive this deep into the inglorious world of Swirl port boat anchors. To keep my sanity I probably need to put an end to this right here right now.

So in closing, as they say;
The 810 casting is not all that different from the 193 casting. There are lots of minor differences, but the main things, casting wise is the added material to cater for press in exhaust valve guides, the press in exhaust seats, and that the entire area where the valve spring pockets are is lowered, there is even a ledge in the inlet ports because of this. Also the overall casting finish is better. And to me the most important diff, way nicer machine work on the inlet valve seats.

193 inlet port, slightly rough casting.

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810 casting, smoother, but with a ledge under the spring pocket area, and also to my surprise a cavernous pocket under the rocker stud. The port roof is also about 1mm lower than the 193 port, so the 810 port might be one or two insignificant CC's smaller.

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The end.

 

[Erik the Awful]

That "bowl hog" cut--is that a fuel-shearing "step" under the valve seat?

It's cut like that because it's the simplest quick and dirty way for the factory to get the seat width correct, me thinks.

Yup. The casting screams "We did the minimum." If you port those, leave those swirl ramps in place, but clean up the casting. There are also plenty of sharp edges and bends in those runners that need cleaning up.

Those thicker valves are also twice the price of the normal valves. I had a few in my $150 L98 that were too pitted to use. I also ditched the rotators and went with standard-style valve retainers and keepers.

I ported my TBI heads after watching the video below. I tried opening up the combustion chamber as he shows on a junk head, but my skills aren't that good yet, so I just did a cleanup porting job.
www.youtube.com/watch?v=QMkCV1s5BQ8

 

[1990Z71Swede]

Yup. The casting screams "We did the minimum." If you port those, leave those swirl ramps in place, but clean up the casting. There are also plenty of sharp edges and bends in those runners that need cleaning up.

Those thicker valves are also twice the price of the normal valves. I had a few in my $150 L98 that were too pitted to use. I also ditched the rotators and went with standard-style valve retainers and keepers.

I ported my TBI heads after watching the video below. I tried opening up the combustion chamber as he shows on a junk head, but my skills aren't that good yet, so I just did a cleanup porting job.
www.youtube.com/watch?v=QMkCV1s5BQ8

Yes, I'm porting these 810's.
I did start working on a set of 193's and if it weren't for that Bowl cut they would be a slightly better starting point. The plan was to get that sorted by recutting the seats for 2.02 valves. But now they are going back on the spares shelf.

These 810 heads are in excellent shape, they also only cost me the Swedish equivalent of $20. And since I'm now staying with the stock Inlet valves it leaves quite a bit of wiggle room for a proper valve job. I don't think those fat exhaust valves impede flow enough for it to matter much, so I'm keeping those too.

Don't worry I'm not going to "unswirl" them, that would be absolutely bat $hit crazy, if at all possible. The benefits of the Swirl port is the only thing they have going for them, I'm just going to try and lessen the drawbacks somewhat.

Oh, yeah almost forgot. I would not listen too much to what the headbytes guy says. My favorite goto for porting info is Eric Weingartner, he is on youtube too.

https://m.youtube.com/@WeingartnerRacing/videos

 

[1990Z71Swede]

CC:ed one Intake port, measuring glass is not calibrated unfortunately.

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I'd say it looks like just a tad over 180cc.. Used concentrated windsceen washer fluid, to my surprise there was still quite a bit of surface tension.

 

[1990Z71Swede]

Wifey found my calibrated metering glass. Did it aaaall over again...with ethanol this time.

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The port is 182CC period.

 

[PlayingWithTBI]

The port is 182CC period.

Hmmm - looks like 181 to me, 230 - 49 = 181 or am I missing something here but, what's one cc among friends?

 

[1990Z71Swede]

Hmmm - looks like 181 to me, 230 - 49 = 181 or am I missing something here but, what's one cc among friends?

Mmm. Maybe you are missing that there is 2 cc 's between the lines? There is 48cc left in the metering glass. Your're not a bartender I hope...