Due to the overwhelming response to my involvement with Singh's
grooves both for and against, here are pictures of my latest work.

These SBF Edelbrock performer RPMs are ready for a FI 351 Windsor Lightning
pick up. I don’t have all of the details, small cam, 10:1 compression street
strip effort.



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Another set of Edelbrock heads these for a 355 SBC going in a 63 Nova
street machine. The engine's nothing special, the car will be top quality!



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We are looking for 650 HP in a previously grooved LT1 running in a high 9
second 65 Corvette. Upgrades include this dual TB dual plane custom intake
manifold and grooved aftermarket heads, the stock heads shown will likely
will be replaced with AFR 210s

Is there any particular explanation for the aiming angles?

I see 3 different styles here.

Yeah, I wondered that too. Are these 3 different motors that you have experimented with or what?

Style 1, third picture. Somender Singh's original recommendation. I have
over 30 engines running with this layout.

Style 2 & 3; my imagination going wild. I have theory behind the madness
but so many get bored when theory is discussed. I have 4 engines with
different variations of this layout.

Here are a few other variations:

I rather not call this experiments, although in some way it is just that. The
only layout I have used on my own engines is the single groove design. My
test engines for 2007 utilize something very different all in an effort to
improve combustion.

Maybe Singh has tried all the possible trenches and settled on this one, but I would be tempted to try something else. It seems to me that more of the mixture could be jetted toward the plug if you were to machine the grooves in a shallow figure "3" pattern. Take your last picture and lay a 3 on the head deck, with the middle arm of the 3 extended into the chamber. Use a large enough 3 so that the top and bottom arms of the figure would extend to the top and bottom of the picture. It seems you would pick up more mixture from the outer parts of the deck instead of losing them in a thin sheet to go wherever. I can visualize a router set up in a track fixture and mounting a carbide ball end mill. Alternately, how about a "T" laid on it's side with the ends of the top bar of the T machined very close to the lip of the flat?

Some of my stuff might sound nutty, but I'm just trying to help.

I somewhat followed your last thread but there's so much there that I don't really want to go back and dig through all 15 pages or whatever to see if my question has already been answered so I apologize if I'm bringing up an old question. I do remember some conversation about testing but how far in depth have you tested the effectiveness of the grooves? Example, have you taken a previously ungrooved set of heads and run them on the engine, using various grades of fuel with a given compression (maybe 10.5:1) while using knock sensors, EGTs, O2 sensors, A/F meters and the like and then tested the exact same engine with the modification?

I plan to do that this spring with vortecs. I have two sets of 906s and (if I can spend the money) I'll set them up identically and run them back to back. I'm hoping to do the dyno with an EFI intake that I just bought so that I can do easy fuel and spark tuning (and knock sensing) on the fly.

That way I can test apples to apples, and then lean out the mix and adjust the timing to take advantage of the grooves properties.

Although I was exposed to this grooving technique 44 years ago, I only recently have been studying in depth the theories involved.

One thing should be noted. The piston has a beveled circumference that traps mixture at TDC, and radial grooves cause the squished mixture to shoot outward as well as inward. hhmmmm.

Also note that Vortec heads have that heavy square boss at the spark plug area that porters usually remove and smooth. Why did the engineers put that there? It looks to me that it creates additional turbulence in the compressed ignited burning mixture. ooooo, Like grooves do ????

Just some of my ramblings.

I think that square boss is a locating device for the manufacturing machinery. Older SBC heads had a small rounded flat area near the spark plug hole that served the same purpose.

AB any thoughts about what effect the grooves have at the top of the exhaust stroke in the configurations where the grooves point at the valve? Strictly from an airflow perspective do you think having the grooves pointing at the exhaust valve helps or hurts the exhaust flow?

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B Sinc

The square raised portion in chamber of vortecs is, believe it or not, there for the head to sit on the pallet while being machined in the transfer line.

Seriously, I am NOT trying to be sarcastic, ok.

The head design engineers who are so ultra critical about combustion swirl, tumble, smog, flow, mileage, etc........ put a big lump in the chamber so that it could sit on a pallet ??

In my opinion the square boss that GM put in the combustion chamber
serves one purpose. That is to move the spark plug to a more central
location to reduce burn duration.

To make the square boss effective at developing mixture movement it
is necessary to mill ~ 0.050" off the head surface to create a squish
zone out of the boss. I rarely use the GM heads because of poor combustion
chamber design and the thin deck. I did a set for my tow truck about
a year ago. With modifications I run 10:1 compression, stock cam on
87 regular.