810 cylinder heads.

[PlayingWithTBI]

Maybe you are missing that there is 2 cc 's between the lines? There is 48cc left in the metering glass.

OOPS, that's what I get for glancing quickly without verifying

Your're not a bartender I hope...

I was but, that was about 45 years ago

 

[1990Z71Swede]

For anyone planning on porting Swirlers...
This guy is going absolutely Crazy on a 193 head.
And its ongoing. Right now he has a 2.10" intake Valve in it, 50 degree valve seat, Combustion chamber opened up to 4.125 bore, the port is at maybe 230cc ? And it is flowing 280cfm at 0.500
that is ABSOLUTELY bonkers and it makes absolutely no sense, but he is aware of this and doing it anyway just for fun and as a learning experience I guess. What´s good about it is that he does not hide his mistakes. For the average shade tree porter it is as much about what not to do as it is about what can be done.

Enjoy:

https://www.youtube.com/@servediocylinderheads/videos

This is before it goes crazy and also how far I would go. Stock size valves (with back cut inlet valve) flows 235cfm at 0.500 which I believe is similar to or maybe even slightly better than untouched Vortecs. (Vortecs do on the other hand often work better than their flow numbers indicate)
The 193´s in the Video still has some potential for improvement with a better valve job

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[Schurkey]

That guy in the video is the same guy on SpeedTalk.com that's doing a swirl-port head for giggles.

I haven't read the thread.

www.speed-talk.com/forum/viewtopic.php?t=67871

Chevy 193 Swirl port Mission Impossible - Don Terrill’s Speed-Talk

 

[L31MaxExpress]

For anyone planning on porting Swirlers...
This guy is going absolutely Crazy on a 193 head.
And its ongoing. Right now he has a 2.15" intake Valve in it, 50 degree valve seat, Combustion chamber opened up to 4.125 bore, the port is at 230cc and it is flowing 280cfm at 0.500
that is ABSOLUTELY bonkers and it makes absolutely no sense, but he is aware of this and doing it anyway just for fun and as a learning experience I guess. What´s good about it is that he does not hide his mistakes. For the average shade tree porter it is as much about what not to do as it is about what can be done.

Enjoy:

https://www.youtube.com/@servediocylinderheads/videos

This is before it goes crazy and also how far I would go. Stock size valves (with back cut inlet valve) flows 235cfm at 0.500 which I believe is similar to or maybe even slightly better than untouched Vortecs. (Vortecs do on the other hand often work better than their flow numbers indicate)
The 193´s in the Video still has some potential for improvement with a better valve job

xc_hide_links_from_guests_guests_error_hide_media

I have long known that a TBI head can flow close to what an untouched Vortec can. The ones I cleaned up with minimal knowledge back in the day flowed 224 cfm @ 0.500. The Canadian 906s flowed 242 cfm @ 0.500 and the Mexican 062s flowed 215 cfm @ 0.400 on the same bench. My stock 810s flowed 178 cfm @ 0.400. I also ported a set of 601s (80s LE9 305 truck heads) and put PEP Pro Valves in them that were undercut stems. Those flowed 226 cfm @ 0.500 through a 1.84 valve keeping ~52cc chambers after 0.020" was taken off them.

 

[1990Z71Swede]

I have long known that a TBI head can flow close to what an untouched Vortec can. The ones I cleaned up with minimal knowledge back in the day flowed 224 cfm @ 0.500. The Canadian 906s flowed 242 cfm @ 0.500 and the Mexican 062s flowed 215 cfm @ 0.400 on the same bench. My stock 810s flowed 178 cfm @ 0.400. I also ported a set of 601s (80s LE9 305 truck heads) and put PEP Pro Valves in them that were undercut stems. Those flowed 226 cfm @ 0.500 through a 1.84 valve keeping ~52cc chambers after 0.020" was taken off them.

Thats some great info right there, thanks

On the other hand, flow numbers are not the whole story.

There is no doubt in my mind that a set of double humps ported to equal or even slightly greater flow numbers than Vortecs will still not perform as good as the Vortecs. Not even if it were posssible to keep the ports for both heads at the same size. (Maybe it is, IDK)

One thing I sorta knew but got verified by watching Eric Weingarter is that more flow does not always equal more hp. And it is not only about keeping air speed up, mixture quality and combustion speed is important too and probably where the Vortecs shine.

That's why I think what this guy does is interesting as he is showing both swirl numbers and air speeds in various parts of the port.

 

[Schurkey]

One of the "secrets" of the Vortec port and valve is that the low-lift flow is outstanding.

The chamber is also very efficient at burning.

 

[1990Z71Swede]

One of the "secrets" of the Vortec port and valve is that the low-lift flow is outstanding.

The chamber is also very efficient at burning.

Yes and low lift flow is important because the valve will spend way more time at "low" lift than it does at maximum lift. (Obviously you know this already, but others might not)

And on a TBI or Vortec truck "maximum" lift most of the times are still pretty low...

 

[L31MaxExpress]

Actually low lift numbers are not as important because most of low-lift is reversion gases anyway. Even a stock cam has overlap. There are several engine builders far smarter than myself that actually have said the ideal intake port and valve job flows nothing until 0.250-0.300 lift and flows as much as possible beyond that. That is the reason a properly ported head responds better to a 50* intake seat. The 50* seat limits curtain area and thuse helps reduce reversion and self-egr at lower rpm.

 

[PlayingWithTBI]

Since we're talking about flow, what about angled vs straight spark plugs. I've heard some say angled gives you better flow due to less "shrouding" of the intake valve. Others say it doesn't make much, if any, difference. What about "indexing" the spark plug?

Here's an example of angled plugs, note the clearance from the intake valve.

You must be registered for see images attach

 

[Schurkey]

The earliest SBC "angle plug" heads were said to be good for ~15 additional horsepower. They were "invented" by taking production-line heads and repositioning the plugs. This was done by/for the infamous Smokey Yunick.

Several generations of those "angle plug" heads were made, all of them using production-line tooling and cores up to the so-called "Turbo" head of the early '70s. After that, multiple generations of the "Bowtie" heads were developed from scratch also having angled plugs and not using production-line casting cores.

At this point in the game the SBC heads--"stock" and various levels of "racing" heads, have had so many generations and so much development by GM and the aftermarket that it's hard to say what has "straight" plugs and what has "angled" plugs that interfere with exhaust manifolds/headers.

The ancient Trick Flow heads I've got are advertised as "angle plug" but the plug locations are such that ordinary headers fit, and fit really well. My spark plug access is probably better than stock; even with my Edelbrock headers plug access is just "poke a socket and extension on 'em" except for #1, where I just reach in with a 5/8 combination wrench. I need no special heat-shielding for my plug wires using the OEM routing and plug-wire looms.

Indexing plugs was said to be good for some power improvement as well. Whether that's still true on modern cylinder heads, I can't say. Indexing plugs was developed when plugs still had gaskets, and small gaps back in the '50s or '60s, and production-line cylinder heads were...crude. Kinda thinking that "time has moved on", but I could be wrong. I bought a set of (Moroso?) spark plug indexing gaskets for gasketed plugs, and for taper-seat plugs...but I never actually used 'em.

Taper-seat version:
www.summitracing.com/parts/mor-71900

Moroso 71900 Moroso Spark Plug Indexing Washers | Summit Racing

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