Jetting by piston color ?????

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T67POWER

T67POWER

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I always jetted my cars by the way the plug looks but recently i started to jet by the color of the piston tops.
I bring the piston to top dead center and look at it with a mag light.
I am finding that this is a good way to jet my cars.
piston color is as follows:1) BLACK= RICH
2)DARK TAN=SLIGHTLY RICH
3)LIGHT TAN WITH SILVER SHOWING ON HIGH SPOTS.( HIGH SPOTS=VALVE RELIEF EDGE OR DISH EDGE) =PERFECT FOR HIGHEST HORSE POWER.

DOES ANYBODY use there piston color as information on what there motor needs for jetting.
TRYING TO KEEPING MY ENGINE HAPPY>>>> :drinkers:
 
I think the best way is to index the plugs and then read them. The piston top will only show some of the info. Plugs themselves show burn temps, mixture, and timing and you can study them a bit easier.
 
sooo your gonna take out all 8 plugs and try to read the a/f by looking at a very limited part of the piston? or will you take the heads off to see if you need to change the jetting?

if anything, the top of the piston right under the plug is NOT where you want to look.
 
A motor that is tuned in, seems to have a light tan piston color and the plugs will look good to.
I think it is more of a real world pitcher of how much fuel is actually being being burnt in the combustion cycle.
The plug is the hottest part of the cylinder and can become hard to read when you start getting close to a perfect air fuel ratio, a little more information is a good thing.
Many other kinds of vehicle racing, jet by the color of there pistons.
Example:Bikes and snow mobiles use this very technique to achieve max power.
 
Those are predominantly 2stroke and higher rpm engines tho. Do you have a lighted magnifying plug reader? Naked eye you are correct. The problem I see is like Bomb says, the area you would want to look at would be away from the plug and not dead center. A borescope would be better than looking throught the hole I think.
 
When you look in threw the spark plug hole, you can see from the edge of the piston all the way to the center.

Why are you trying to stay away from the spark plug for a reading anyway??

Most people read the plug it self, and that is hotter then anything in the cylinder.

When the mixture starts to get close to being on the money and shows a light tan color,you will notice it get's easier to see the piston top.
The lighter color of the piston will reflect the light from the flash light beam better then a coal black piston.
 
Piston top color can be affected by oil past the rings. You might get a ballpark reading, but best way to jet is by 1/4 mile MPH reading......as long as you can do it with consistent weather conditions, mainly wind, as well as launch and shift the car consistently to eliminate variables.
 
Locomotion,whats up 360 crate racer.
mph is horse power.very true.8)
 
Hi!
My piston tops are normally black with a little aluminum showing around the outer edges. But then I run a low tension oil ring. My plugs are usually pretty lean-looking. But I did notice an obvious variation when jetting with a Weiand Stealth dual plane. I had them all in a holder and noticed a pattern despite square jetting. The cylinder plugs fed by by the upper level of the dual plane were more tan (richer) than the cylinder plugs fed by the lower level. I forgot which way I went, but I changed jets by 2 or 3 numbers on one side to even out the coloring and picked up a little.

It's difficult to get it exact, especially when weather and seasons can change the A/F ratio.
But I still rely on MPH when jetting.
 
"When you look in threw the spark plug hole, you can see from the edge of the piston all the way to the center.
Not on any I've peaked in. I can see about 10% of the surface area (size of a quarter or so), or about 15% of the area under the valves, and it's under the wrong valve(intake). But I'm not really looking hard anyway so maybe that's why.


Why are you trying to stay away from the spark plug for a reading anyway??
The plug starts the burn. It is not the hottest part, that's the exh valve area. I want a complete controlled burn all the way accross the chamber which means the entire area under the valves. Which as I said above, I can't see.

Most people read the plug it self, and that is hotter then anything in the cylinder.
Exh valve and seat area is hottest. Intake valve and plug area is not.

When the mixture starts to get close to being on the money and shows a light tan color,you will notice it get's easier to see the piston top.
The lighter color of the piston will reflect the light from the flash light beam better then a coal black piston."
If you say so...lol
 
Get a base jetting run the car...up the jets,run the car if it goes faster up the jets again,and continue to up the jets until the car goes slower then a previous run,put the previous jets back in and your in business..of coarse this is what track rentals are good for because you can get 12+ runs in,and of coarse weather has a lot to do with it too,i find myself changing jets just about every trip to the track,but thats part of racing..oh and i read the plugs too,never heard of that reading the piston thing..
 
stroked 340 said:
i find myself changing jets just about every trip to the track,but thats part of racing..oh and i read the plugs too,never heard of that reading the piston thing..
Click to expand...

Too much work, jet it just a tad rich for average weather and you're covered. Screw that changing jets every race. What a waste.
 
I stuck my car on a chassis dyno ($50 for 1/2 hour). Probe in the exhaust reading AFR over the RPM range.

Worth the money in my opinion.
 
Locomotion said:
Hi!
My piston tops are normally black with a little aluminum showing around the outer edges. But then I run a low tension oil ring. My plugs are usually pretty lean-looking. But I did notice an obvious variation when jetting with a Weiand Stealth dual plane. I had them all in a holder and noticed a pattern despite square jetting. The cylinder plugs fed by by the upper level of the dual plane were more tan (richer) than the cylinder plugs fed by the lower level. I forgot which way I went, but I changed jets by 2 or 3 numbers on one side to even out the coloring and picked up a little.

It's difficult to get it exact, especially when weather and seasons can change the A/F ratio.
But I still rely on MPH when jetting.
Click to expand...
edel. performers run lean on a couple of cyl. also
 
moper said:
You don't race Stock Eliminator... or in the Northeast do you...lol.
Click to expand...

The stocker is injected but no, I don't race in the northeast. It's usually just hot here, all year 'round. I don't see how you can possibly get a handle on your dial in though if you are constantly changing jets every race. Just dial for the weather instead of jetting for the dial.
 
No....I would never change my practices and start jetting by Piston Crown color/texture.

It is far simpler, and requires less time and intial investment, to JUST READ THE SPARK PLUGS...there is a guide to burn color in most Haynes/Chiltons...and experience will only accumulate with time.

I like to use a White LED Pen light, while in a dark room with a magnifying glass inspecting the porcelain from electrode up into the body....but to each their own.


This brings up something I was just thinking today....somewhere along the road...the whole world advanced a little bit too far from simple....and I want to pick on Ford Engineers...Cars used to be pretty simple....now...a car is a rolling space shuttle with chinese electrical components made with copper from all of our old good simple cars.
 
stroked 340 said:
Really,to each his own..
Click to expand...

Really, what's the point? Is it going to pay more if you run 11.70 instead of 11.80? I know I could run anywhere from 10.00 to 19.99 and it pays the same. That's what they make weather stations for so you can adjust your dial in instead of changing things on the car so you'll have no idea what it will run.
 
Hey guitar jones,
What if we take that one step further and keep the same combination year after year.
How consistent would your ET be then.
People change there cars performance every year and then can't understand how they keep running off there number.
I think it's hard enough to dial with the weather always changing throughout the day and the track conditions playing with your ET.
BOY,WHAT A CONCEPT >>>>>>>>>>>>>>>.
 
Hey guitar jones,
What if we take that one step further and keep the same combination year after year.
How consistent would your ET be then.
People change there cars performance every year and then can't understand how they keep running off there number.
I think it's hard enough to dial with the weather always changing throughout the day and track conditions changing your ET.
BOY,WHAT A CONCEPT >>>>>>>> :sad6: it's just too boring to go the same speed i guess or there are to many summit and jeg's catalogs hanging out during the winter.
 
Guitar Jones said:
The stocker is injected but no, I don't race in the northeast. It's usually just hot here, all year 'round. I don't see how you can possibly get a handle on your dial in though if you are constantly changing jets every race. Just dial for the weather instead of jetting for the dial.
Click to expand...

Literally years of records... I dont race much but my friends do. The altitudes in the northeast can change by thousands of feet in a day, nevermind the 3K foot difference between NJ, upstate NY, and NH. Even a bracket racer needs the log book and most will need to make changes between first round and finals of the same day, especially with a 4sp car. Many own a weather station. The S/D guy could run his car from FL to Canada and the records were there to go back to. The slower cars and automatics are not as susceptable. Slower being ETs slower than around 11.50s.
 
Well here in the northeast where i race the weather can change in a matter of minutes/hours..it can 50's at the start of time trials and 70's by the end same with eliminations can be 70's and 85 before you know it,so jetting is a must in this area..:-D:-D
 
The weather changes here too. My car may run up to a tenth difference over the course of a day/night. Keeping records is key and I can look at the weather and pretty well predict what my car will run to within .007 of a second. Much better now that I have a 4 link car over the CalTracs. That has taken the 60' variance right out of the equation.

As far as people that keep changing stuff on their car, it's true, trying to dial a car that you have no records on or experience with makes it damn near impossible. If you dial it accurately it was probably just luck.

The one guy at our track that was track champion for like 15 years raced the same car without making any changes to it. If something broke he bought the same exact piece to replace it. He knew that car better than the back of his hand.
 
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