Harley Singh Grooves

t120r's picture

Hey guys. My first project in fuel economy is gong to be with my 2003 Harley Sportster. It already gets 3.5l/100km, but I have the Edelbrock 1200cc conversion kit. So I'll be increasing the displacement from 883cc to 1200cc and also increasing compression from 9:1 to 10.5:1. Now this kit as delivered is pretty detonation resistant... For a Harley anyway.:) . I already have the pistons coated with a thermal barrier and I will be doing the same to combustion chamber, valve faces and exhaust runner/port. Soon I will be ripping the cylinders off to be rebored for the new pistons, so the heads have to be ready to go. Basically what I need to know is what the optimal quench is for the singh grooves. By removing the base gasket I'm told I should come into a squish band somewhere in between 0.030" and 0.040", which comes out to about 11.2:1 compression ratio. Will the be too small of a gap for them to work? I really don't want to shave down my new heads to increase compression. Any ideas or suggestions would be greatly appreciated.

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Re: Harley Singh Grooves

mpgmike's picture

0.030" - 0.040" is a bit thin for the Groove to work properly. It would help if you could post pics of your pistons and combustion chamber. The Somender Grooves are just a tool. They accomplish something. What they accomplish is determined by how you use them. Let's see what you're working with.

Mike

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Re: Harley Singh Grooves

t120r's picture

Here is a pic of the chamber. I should have zoomed out a bit more. If it's not enough, let me know and I'll take another one.
The pistons in this kit are specially made by JE for Edelbrock. The dome (10cc after radius & polish) is designed to fit the head pocket. These are already done with thermal barrier coating, so I won't be touching them again.

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Re: Harley Singh Grooves

Pinhead's picture

I would "edge" that chamber in addition to adding Singh Grooves. There's a lot of improvement to be had. I'll wait for Mike to suggest groove position of the groove(s), though, as he has MUCH more experience. :)

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Re: Harley Singh Grooves

t120r's picture

Oy yes. The chamber needs to have the edges radiused for sure. I have a dremel I was going to use for it, but instead I am going to use an air diegrinder with a rolox pad. That will make a much nicer/smoother job.

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Re: Harley Singh Grooves

mpgmike's picture

I would add 2 grooves per cylinder; one behind the spark plug, aimed at the spark plug, and one opposite the plug, aimed just toward the exhaust side of the spark plug. +1 on the radiusing.

Mike

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Re: Harley Singh Grooves

t120r's picture

Thanks for the advice. The more I think about it, the more I am contimplating shaving the head down a bit. Every 0.010" milled off will bring roughly 1.1cc out of the chamber. Basically with the radiusing and the singh grooves, I could shave off 3cc or so and still come out with a touch more compression.

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Re: Harley Singh Grooves

daves66nova's picture

So how did this run after all?

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Re: Harley Singh Grooves

Pinhead's picture

I'm curious as well. And always enjoy looking at combustion chamber porn. :D :mrgreen:

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Re: Harley Singh Grooves

threepiston's picture

Me too, as I have an 03 sportster in the barn available to me for cheap.....

Combustion chamber porn... LOL. I like engine porn.... I don't just have a chamber fetish....

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Re: Harley Singh Grooves

t120r's picture

Sorry I haven't updated this... I had the heads shaved 0.030", radiused the edges and polished the chamber to a mirror finish. I still haven't put in the grooves as I don't have access to a mill anymore so I'm trying to figure a good way to do it accurately.

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Re: Harley Singh Grooves

daves66nova's picture

I used a dremel tool with a ball tip to groove the heads.

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Re: Harley Singh Grooves

octfifty's picture

Ball mill with 1/4 inch shank will fit in a routermake a router template using bolt holes for reference. Slow and easy does it works on aluminium cann't say on iron.

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Re: Harley Singh Grooves

t120r's picture

Update: SO my heads are shaved 0.030". The edges are radiused and the chamber is polished. I took out my new powerlynze tools and started at it. All I have left to do is cut the Singh Grooves. I'm kind of nervous about it, but what the heck:) Give it a go.:) I have a 1/16" ball mill and a dremel... Pics will follow when I finish it. Hopefully done tonight.

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Re: Harley Singh Grooves

Pinhead's picture

Don't forget pics of the ports! I want as many pictures to compare my work to!!! :D

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Re: Harley Singh Grooves

smitty's picture

What did you decide on the squish dimension? I would have thought you'd have set that first, before shaving the heads, so that you would know where the cc's and static c.r. are going to come out.

Mike, I don't get why a loose squish would (as I read on Singh's site) do anything to help the effect of grooving. Seems like it be just the opposite. In the old days, before Singh, before fire-slots, et al, tight (cautiously tight!) squishbands went a long way toward doing what the grooves now do somewhat better. Why not tight squish with grooves? Has anybody actually isolated and tested this variable?

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Re: Harley Singh Grooves

mpgmike's picture

About 2 years ago someone was doing extensive testing on a Geo Metro 3-cyl engine. Apparently, he was equipped with some pretty sophisticated equipment to see what goes on. I don't remember his name, but a search of the site might bring the subject up. If anybody did that sort of testing it would either be him or Automotive Breath.

Mike

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Re: Harley Singh Grooves

Pinhead's picture

mpgmike wrote:

About 2 years ago someone was doing extensive testing on a Geo Metro 3-cyl engine. Apparently, he was equipped with some pretty sophisticated equipment to see what goes on. I don't remember his name, but a search of the site might bring the subject up. If anybody did that sort of testing it would either be him or Automotive Breath.

Mike

threepiston perhaps?

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Re: Harley Singh Grooves

threepiston's picture

Not me, but that's where my username comes from.... :D

Squish is pretty cool too though. 305 heads on a 350 raise the compression some, but it also has a few other benefits. It provides about an 1/8" squish band around the perimeter of the bore due to the bore difference, and the valves and ports are slightly smaller which increases velocity. That mod really wakes up a stock 350.

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Re: Harley Singh Grooves

smitty's picture

Where is Automotive Breath these days? I e-mailed him a month ago, but heard nothing back.

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Re: Harley Singh Grooves

threepiston's picture

He's usually here or at SpeedTalk...

P.S..... If anyone is thinking of doing a 4/6 drop on a 73-87 Chevy, don't use a Mcgaughy's kit, unless you can figure it out on your own, with little to no instructions... "Use wheel "CHALKS"".. Last time I checked, they were called chocks.... "you may have to CUT the bed support.." I used two chisels to lift the bed in order to get the bed high enough to clear the C-Notch kit.... No cutting involved. Looks like someone outsourced to China, or earned a degree without knowing which way was up... The finished product turned out nice though...

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Re: Harley Singh Grooves

t120r's picture

Hmmm... I'm all ready to do my grooves, but can't seem to get it straight on my practice scrap aluminum block. Lost my access to a milling machine. Now I have to figure out a way to cut them.

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Re: Harley Singh Grooves

mpgmike's picture

I don't know where you're located, but if time is NOT of the essence, I could cut them for you. Just pay for shipping.

Mike

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Re: Harley Singh Grooves

t120r's picture

Thanks for the offer man. Really great of you. Just I would like to do them myself. I think I may be able to get near a mill at work to do it. Have to chat it up with the guys in that department tonight.

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Re: Harley Singh Grooves

smitty's picture

threepiston wrote:

He's usually here or at SpeedTalk...(unquote)

I just did the Advanced Search for posts by Automotive Breath in Engines and Sommender's Grooves and get nothing. I'll check Speedtalk.

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Re: Harley Singh Grooves

Eric's picture

Try "automotivebreath" (one word)

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Re: Harley Singh Grooves

smitty's picture

Thanks, Eric. I've tried elsewhere with no answer, and maybe he thinks I'm pursuing him around the internet, so I've decided to forget it. If we run into each other, good; if not, that's life.

t120r, if you look at Singh's own site, and at the photos of his grooves, you can see they were NOT done on a milling machine, but were probably done with a skunk-wheel (very narrow abraisive disk) in a hand-held air-motor or side-grinder. Not particularly precise work, in fact a little rough, it seemed to me. The air doesn't know the difference. I haven't been to Singh's site in a long time; maybe he has a milling machine now. But if your hand is steady and you have some feel for what you are doing, then surely the point at which you aim the groove is going to matter a lot more than whether it is made with machine tool accuracy. Automotive Breath gave some guidlines on what he felt, after having done a bunch of engines, was a workable size range for a groove, but I don't think he or anybody else has yet "proved" anything about that or about aiming the grooves. I don't know that such things CAN be proved in such a way as to give us universal guidlines applicable to a wide range of combustion chamber shapes. Anyway, if you happen to luck out and get the aim exactly right, I can't see where you'll be hurt by a hand-made groove, and if you aim for the wrong place, a machined groove won't make it work any better, IMOH. This principle is emphatically the case for grinding on ports, esp. 2-stroke ports, and anybody who does this will tell you that size and shape and aim-point count for a whole lot more than surface finish and minor disuniformities along the way.

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Re: Harley Singh Grooves

t120r's picture

Sorry for lack of an update, but work has been crazy. I convinced management that our old Bridgeport mill is invaluble to us, so it was fixed yesterday.:) I'll try and groove my heads tomorrow when no one is around.:)

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