Burn patterns on piston and chamber

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Lloyd klem
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Re: Burn patterns on piston and chamber

Post by Lloyd klem »

1980RS wrote: Sat Dec 03, 2022 8:30 pm My chambers on the L-29 heads and piston crowns looked super after using a burr finish in the intake ports and chambers. I am sold on doing the burr finish after testing it with 2 different sets of heads. Never had intake ports so clean after a few races.
I have never needed any reason to use a burr finish.Get your shape ,csa,correct and it all takes care of itself.You never see a burr finish in nascar stuff,I never see burr finish in anything that comes out of top shops in country,Foltz does as nice as work as anything I have held in my hands.I never see any type of burr finish from him.To each their own but I see it as a bandaid and nothing more.jmo
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Re: Burn patterns on piston and chamber

Post by SpeierRacingHeads »

Lloyd klem wrote: Sat Dec 03, 2022 8:45 pm
1980RS wrote: Sat Dec 03, 2022 8:30 pm My chambers on the L-29 heads and piston crowns looked super after using a burr finish in the intake ports and chambers. I am sold on doing the burr finish after testing it with 2 different sets of heads. Never had intake ports so clean after a few races.
I have never needed any reason to use a burr finish.Get your shape ,csa,correct and it all takes care of itself.You never see a burr finish in nascar stuff,I never see burr finish in anything that comes out of top shops in country,Foltz does as nice as work as anything I have held in my hands.I never see any type of burr finish from him.To each their own but I see it as a bandaid and nothing more.jmo
I have never seen a cylinder head that allows proper cross section help with burr finish. I have seen it help velocity limited heads. However, CNC lines, step overs, all that has been mastered by those guys. They are using that as a means of manipulation.
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Re: Burn patterns on piston and chamber

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SpeierRacingHeads wrote: Sat Dec 03, 2022 8:48 pm
Lloyd klem wrote: Sat Dec 03, 2022 8:45 pm
1980RS wrote: Sat Dec 03, 2022 8:30 pm My chambers on the L-29 heads and piston crowns looked super after using a burr finish in the intake ports and chambers. I am sold on doing the burr finish after testing it with 2 different sets of heads. Never had intake ports so clean after a few races.
I have never needed any reason to use a burr finish.Get your shape ,csa,correct and it all takes care of itself.You never see a burr finish in nascar stuff,I never see burr finish in anything that comes out of top shops in country,Foltz does as nice as work as anything I have held in my hands.I never see any type of burr finish from him.To each their own but I see it as a bandaid and nothing more.jmo
I have never seen a cylinder head that allows proper cross section help with burr finish. I have seen it help velocity limited heads. However, CNC lines, step overs, all that has been mastered by those guys. They are using that as a means of manipulation.
That sounds like a fair assessment.
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Re: Burn patterns on piston and chamber

Post by Lloyd klem »

SpeierRacingHeads wrote: Sat Dec 03, 2022 8:48 pm
Lloyd klem wrote: Sat Dec 03, 2022 8:45 pm
1980RS wrote: Sat Dec 03, 2022 8:30 pm My chambers on the L-29 heads and piston crowns looked super after using a burr finish in the intake ports and chambers. I am sold on doing the burr finish after testing it with 2 different sets of heads. Never had intake ports so clean after a few races.
I have never needed any reason to use a burr finish.Get your shape ,csa,correct and it all takes care of itself.You never see a burr finish in nascar stuff,I never see burr finish in anything that comes out of top shops in country,Foltz does as nice as work as anything I have held in my hands.I never see any type of burr finish from him.To each their own but I see it as a bandaid and nothing more.jmo
I have never seen a cylinder head that allows proper cross section help with burr finish. I have seen it help velocity limited heads. However, CNC lines, step overs, all that has been mastered by those guys. They are using that as a means of manipulation.
I think you do understand why it is something that is needed at times.I have also saw tho where guys are just doing it to everything they touch.i don't think that's needed at all but again to each their own.I have taken things that have came to me that I couldn't fix and had to rough an area in throat area because valve job was wiped out where it was needed.I have had to do it on intake of chamber to alter or add some swirl because of poor design or shape or someone over greedy with a die grinder etc.I just use a texture Tootsie roll finish but I do alter how and what direction it goes.I work with pretty small rpm windows fairly high upstairs.It doesn't require same fixes etc that a 3500 rpm swing needs etc.
Last edited by Lloyd klem on Sat Dec 03, 2022 9:11 pm, edited 1 time in total.
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Re: Burn patterns on piston and chamber

Post by SpeierRacingHeads »

Lloyd klem wrote: Sat Dec 03, 2022 9:08 pm
SpeierRacingHeads wrote: Sat Dec 03, 2022 8:48 pm
Lloyd klem wrote: Sat Dec 03, 2022 8:45 pm
I have never needed any reason to use a burr finish.Get your shape ,csa,correct and it all takes care of itself.You never see a burr finish in nascar stuff,I never see burr finish in anything that comes out of top shops in country,Foltz does as nice as work as anything I have held in my hands.I never see any type of burr finish from him.To each their own but I see it as a bandaid and nothing more.jmo
I have never seen a cylinder head that allows proper cross section help with burr finish. I have seen it help velocity limited heads. However, CNC lines, step overs, all that has been mastered by those guys. They are using that as a means of manipulation.
I think you do understand why it is something that is needed at times.I have also saw tho where guys are just doing it to everything they touch.i don't think that's needed at all but again to each their own.I have taken things that have came to me that I couldn't fix and had to rough an area in throat area because valve job was wiped out where it was needed.I have had to do it on intake of chamber to alter or add some swirl because of poor design or shape or someone over greedy with a die grinder etc.
Agree, And I've done it to help try to straighten out just bad porting from someone else!
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Re: Burn patterns on piston and chamber

Post by swampbuggy »

Hello Chad, what do you mean by ( Step Overs ) ? Thanks , Mark H. Central Fla.
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Re: Burn patterns on piston and chamber

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"Spark plug wetting seems to be an issue for a lot of early OEM type cylinder heads."

Not if carb is set up correctly.
Looks like fuel wash/overly rich AFR. ( probably at part throttle )
I assume this is a street/strip engine. The mistake (racers ) most people make is setting up AFR for WOT and calling it a day.
What about idle/off idle and cruise AFR?
Even racers will have a happier engine if you take care of that. For a drag racer , having an engine that runs strong at part throttle can pay dividends on the return road to the pits.
For circle track racers , fuel consumption can be a factor in winning.
Do you use an AFR gauge ?
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Re: Burn patterns on piston and chamber

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Lloyd klem wrote: Sat Dec 03, 2022 7:28 pm
Erland Cox wrote: Sat Dec 03, 2022 6:14 pm Image

With burr finish in ports and chamber.
Should I try burr finish on the piston too?

Erland
If my stuff looked that bad I would consider it and I don't burr finish anything.Jmo.It is consistent tho across whole layout.Looks way over fueled/oily compared to what I'm used to seeing.I would work on my valve job and really look at my honing procedure in a mess like that.I would check what ring edges and ring lands look like also.
The rings on that engine where a little used up and the block cracked so it is getting a new block.
No oiling whatsoever on spark plug.
Valve job 75-69-45-35 and 30 degree back cut. What would you change.
It is not a dragracing engine but a roadracing and dyno engine so it runs very long between overhauls.
As long as it dynos OK I keep running it.
It doesn´t smoke or use much oil.
Wet sump and you can´t fill past half full because the oil will hit the crank in turns.
Dyno tested for tune and runs above AFR13 at maximum torque.
Only rich where the exhaust tunes bad in the bottom just below 4000.
Pulls great from 2500 to 8000 and has over 100 hp per liter from 6300 to 8300.

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Re: Burn patterns on piston and chamber

Post by Erland Cox »

I did a test with both EFI and carburetors on 2 manifolds, one 60 grit and the other burr finished.
The head was burr finished and only the manifolds changed.
Not even with EFI was it possible to get good accelerator enrichment without overshoot on the 60 grit manifold.
It had to have so much fuel that it always went rich at the end of enrichment.
No such problems with the burr finish manifold.
So I would like to ask the experts if they know why we need acceleration enrichment?
The reason is quite eye opening and it is not what you have been taught.

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Re: Burn patterns on piston and chamber

Post by juuhanaa »

Erland Cox wrote: Sun Dec 04, 2022 6:32 am I did a test with both EFI and carburetors on 2 manifolds, one 60 grit and the other burr finished.
The head was burr finished and only the manifolds changed.
Not even with EFI was it possible to get good accelerator enrichment without overshoot on the 60 grit manifold.
It had to have so much fuel that it always went rich at the end of enrichment.
No such problems with the burr finish manifold.
So I would like to ask the experts if they know why we need acceleration enrichment?
The reason is quite eye opening and it is not what you have been taught.

Erland
Good question Erland. Let me start by saying that i am no expert and have not read any engine design book from start to finish.. Anyway, since im interested in hearing your thoughts on this, i gave my best guess.

At the point where the throttle is slammed wide open, the stuff gets more dense, so we add more fuel, which causes a pudle and raw fuel to be drawn into the engine, and to prevent this we can try burr finishing to delay it?



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Re: Burn patterns on piston and chamber

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He is using ms109 fuel. Makes what ?1.5hp per cube . Highly doubt anyone could make more with parts being used.
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Re: Burn patterns on piston and chamber

Post by Lloyd klem »

brentry wrote: Sun Dec 04, 2022 8:03 am He is using ms109 fuel. Makes what ?1.5hp per cube . Highly doubt anyone could make more with parts being used.
That burn pattern or lack of tells me there is quite a bit left.A good running engine has a nice even burn across 90 percent of piston and chamber.It should have a light gray/tan light dusty texture if right.When you have a sludge look across 1/3 of your piston and no even heat or cover across the rest ,you are leaving pretty good power behind.Could be cyl prep or ring type issue but I see allot of room in the valve job in that pic that needs addressed also.It will taking going to a bigger valve to get all the cuts sharp and correct again,it don't look like it could be fixed any other way.jmo.No disrespect to anyone involved but I see allot could be improved on.I never put a engine together without roll radius the sharp edges and laying some texture on top of piston to help with a even burn.im no fan of flattops to get a nice mixture motion,if that's used your valve job and head and ring seal needs to 100 percent on point.
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Re: Burn patterns on piston and chamber

Post by Lloyd klem »

Erland Cox wrote: Sat Dec 03, 2022 6:14 pm Image

With burr finish in ports and chamber.
Should I try burr finish on the piston too?

Erland
That chamber and plug both show me plenty of oil introduced into the burn there.That being said I wouldn't want the base threaded area hanging into that combustion area with that much oil in the burn.That plug alone shows me this engine needed assistance way before it got to point it did.I see guys so worried about what head ,what intake is best,when what I truly see is not that.What needs to be addressed is getting back to basics of good valve job and most importantly ,ring seal.There is nothing in that chamber pic that even resembles a happy engine.I have worked on dozens of engs with same perimeters you guys are and when they are happy even on pump piss they have nice even burn across 90 percent of chamber and piston top.Light gray or tan is what you want.Even a little light dusty off white will work.But it shouldn't look like raw sewage !!
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Re: Burn patterns on piston and chamber

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Lloyd klem wrote: Sun Dec 04, 2022 11:26 am
Erland Cox wrote: Sat Dec 03, 2022 6:14 pm Image

With burr finish in ports and chamber.
Should I try burr finish on the piston too?

Erland
That chamber and plug both show me plenty of oil introduced into the burn there.That being said I wouldn't want the base threaded area hanging into that combustion area with that much oil in the burn.That plug alone shows me this engine needed assistance way before it got to point it did.I see guys so worried about what head ,what intake is best,when what I truly see is not that.What needs to be addressed is getting back to basics of good valve job and most importantly ,ring seal.There is nothing in that chamber pic that even resembles a happy engine.I have worked on dozens of engs with same perimeters you guys are and when they are happy even on pump piss they have nice even burn across 90 percent of chamber and piston top.Light gray or tan is what you want.Even a little light dusty off white will work.But it shouldn't look like raw sewage !!
Just curious, what type of racing do you do? Class racer?
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Re: Burn patterns on piston and chamber

Post by Lloyd klem »

I have 383 street strip car.It has 1600 miles on it and 40 plus 1/4 mile passes on it.It gets driven to and from track pulling trailer with tires,gears,tools etc.13.35 to 1 comp.Its E30 pump gas ethanol blend.It weighs 3450ish with me.last time out we were trying to get to 120 mph in 1/8th and in 8s and 150 mph in 1/4.The plugs have been it for 800 plus miles and it least 30 passes.You can see the octane boost yellow color in it.But I can see from gray -slightly dusty color this engine is very happy.I can tell ring seal is great and I would bet anything has great piston/chamber coverage of same color.Pulled headers and they have nice light gray/tannish tint.You can tell plug has been in it for awhile because sharp edges are off strap etc.
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