Burn patterns on piston and chamber
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Burn patterns on piston and chamber
Spark plug wetting seems to be a issue for a lot of early OEM type cylinder heads.
The fuel used here was MS109
I am interested in opinions on what guys think is happening in the burn process.
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steve c
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Re: Burn patterns on piston and chamber
Do you have a back cut on the intake valve?
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Re: Burn patterns on piston and chamber
50 degree seats and no back cuts
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Re: Burn patterns on piston and chamber
You could pull a bunch of fuel out of that.Your pistons don't have near enough coverage imo.Need to get some texture too them.
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Re: Burn patterns on piston and chamber
Yes,you are leaving a bunch of power behind there.Im no flat top piston fan at all .That being said even on alky piston should have 95 percent plus coverage if your engine is sealed and your valve job is correct.
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Re: Burn patterns on piston and chamber
With burr finish in ports and chamber.
Should I try burr finish on the piston too?
Erland
Re: Burn patterns on piston and chamber
Hottest part stains first, hold it full load at 6000 for several minutes and I think it'll look a lot different.steve cowan wrote: ↑Sat Dec 03, 2022 2:48 pm 20221203_182359.jpg20221203_180151.jpg
Curious on what to look for and which direction one should take when looking at burn patterns.
Spark plug wetting seems to be a issue for a lot of early OEM type cylinder heads.
The fuel used here was MS109
I am interested in opinions on what guys think is happening in the burn process.
Ignorance leads to confidence more often than knowledge does.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Nah, I'm not leaving myself out of the ignorant brigade....at times.
Re: Burn patterns on piston and chamber
I assume this is an engine you built so I don't have to ask you about texture in the intake manifold or ports. The fuel is dropping out of suspension and you need less quench area. A lot of people thru the years have added fuel coolers . Cold air, hot fuel is a key. And yes, I agree with others, you are extremely rich. Some of this could be the fuel suspension problem.
Heat is energy, energy is horsepower...but you gotta control the heat.
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Re: Burn patterns on piston and chamber
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.Erland Cox wrote: ↑Sat Dec 03, 2022 6:14 pm
With burr finish in ports and chamber.
Should I try burr finish on the piston too?
Erland
Last edited by Lloyd klem on Sat Dec 03, 2022 7:34 pm, edited 1 time in total.
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Re: Burn patterns on piston and chamber
Good point tom,Tom68 wrote: ↑Sat Dec 03, 2022 6:20 pmHottest part stains first, hold it full load at 6000 for several minutes and I think it'll look a lot different.steve cowan wrote: ↑Sat Dec 03, 2022 2:48 pm 20221203_182359.jpg20221203_180151.jpg
Curious on what to look for and which direction one should take when looking at burn patterns.
Spark plug wetting seems to be a issue for a lot of early OEM type cylinder heads.
The fuel used here was MS109
I am interested in opinions on what guys think is happening in the burn process.
Engine was dynoed for Max power.
When looking at this chamber and piston one has to consider some street miles and driving around pits as well.it looks to me like the engine was cold so to speak.
The carbon is not a build up but like a stain if that makes sense.
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Re: Burn patterns on piston and chamber
Super Stock engine off the dyno.
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Re: Burn patterns on piston and chamber
From memory we were 8% richer than stoich for MS109.Lloyd klem wrote: ↑Sat Dec 03, 2022 5:15 pm You could pull a bunch of fuel out of that.Your pistons don't have near enough coverage imo.Need to get some texture too them.
Is the unleaded fuel making this look worse than what it is??
We can not run leaded fuel in Australia.
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Re: Burn patterns on piston and chamber
All exhaust ports and valves look like this
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steve c
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Re: Burn patterns on piston and chamber
I thought on a 23 degree head you need that quench to help with mixture motion etc.In-Tech wrote: ↑Sat Dec 03, 2022 6:29 pm I assume this is an engine you built so I don't have to ask you about texture in the intake manifold or ports. The fuel is dropping out of suspension and you need less quench area. A lot of people thru the years have added fuel coolers . Cold air, hot fuel is a key. And yes, I agree with others, you are extremely rich. Some of this could be the fuel suspension problem.
Just for reference this has 0.030"
Piston to head clearance.
steve c
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Re: Burn patterns on piston and chamber
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.