Fred K-OR
Well-known member
Thanks CarlG. I will have to look at HF. Gives me a chance to go in there and see what things I can't live without.
Spark plugs?
- Thread starter marty in Ohio
- Start date
Thanks CarlG. I will have to look at HF. Gives me a chance to go in there and see what things I can't live without.
Mike V. Florida
Well-known member
More info from Larry;
"Reading the plugs" can be used to determine all sorts of engine problems. BUT, it must be known that the correct plug was used to start with before any problems occurred.
A heat range test is the best way to determine the correct spark plug for a particular engine set up and a person's driving habits. When in doubt always choose a colder plug first until you determine what works best. The worst thing that can happen is the plug can foul out whereas too hot a plug can cause pre-ignition and possible piston damage, i.e., a hole melted right through the piston! Some of you may think it's baloney but it's the truth.
Conduct a heat range test as follows:
Drive out someplace where you can run the car at a sustained speed for a few miles without having to slow down or stop; very important. This allows the heat to build.
Run the car up to the maximum speed in high gear that you would typically drive if you decided to drive fast, and I don't mean dangerously high speed. Hold the car at that sustained speed and without letting off the throttle, reach over and turn off the ignition. Let off the throttle, push in the clutch right quick and coast over to the side of the road. Open the hood and allow the engine to cool off a bit. Remove the spark plugs and examine the color and condition of the electrodes and insulators. The color will be a true indication of how hot or cold the plugs are running.
Now remember this .... if you run the engine and then let it slow down or idle and then check the plugs, you will not get a true indication of the heat!
Of course this is not all set in stone. A person who putts around at say 35 or 40 MPH and never faster may need a hotter plug. The lower the combustion chamber temperature, the hotter the plug should be. On the other hand, as conditions cause the combustion chamber temperature to rise, a colder plug may be necessary. Also, a fuel mixture that is too rich or too lean can confuse the readings; plus a poor ignition system, poor compression, an oil burner, etc., etc.; so the accuracy of the above depends on an engine with proper function.
In conclusion, the plugs should run hot enough to keep the deposits burned off and that's it.... This means the color should range anywhere from light brown to grayish tan. Sooty black is too cold and chalky white is too hot.
Larry B.
"Reading the plugs" can be used to determine all sorts of engine problems. BUT, it must be known that the correct plug was used to start with before any problems occurred.
A heat range test is the best way to determine the correct spark plug for a particular engine set up and a person's driving habits. When in doubt always choose a colder plug first until you determine what works best. The worst thing that can happen is the plug can foul out whereas too hot a plug can cause pre-ignition and possible piston damage, i.e., a hole melted right through the piston! Some of you may think it's baloney but it's the truth.
Conduct a heat range test as follows:
Drive out someplace where you can run the car at a sustained speed for a few miles without having to slow down or stop; very important. This allows the heat to build.
Run the car up to the maximum speed in high gear that you would typically drive if you decided to drive fast, and I don't mean dangerously high speed. Hold the car at that sustained speed and without letting off the throttle, reach over and turn off the ignition. Let off the throttle, push in the clutch right quick and coast over to the side of the road. Open the hood and allow the engine to cool off a bit. Remove the spark plugs and examine the color and condition of the electrodes and insulators. The color will be a true indication of how hot or cold the plugs are running.
Now remember this .... if you run the engine and then let it slow down or idle and then check the plugs, you will not get a true indication of the heat!
Of course this is not all set in stone. A person who putts around at say 35 or 40 MPH and never faster may need a hotter plug. The lower the combustion chamber temperature, the hotter the plug should be. On the other hand, as conditions cause the combustion chamber temperature to rise, a colder plug may be necessary. Also, a fuel mixture that is too rich or too lean can confuse the readings; plus a poor ignition system, poor compression, an oil burner, etc., etc.; so the accuracy of the above depends on an engine with proper function.
In conclusion, the plugs should run hot enough to keep the deposits burned off and that's it.... This means the color should range anywhere from light brown to grayish tan. Sooty black is too cold and chalky white is too hot.
Larry B.
I see this is an old thread but I'm presently trying to figure out the pre detonation problem with my car. 1929 model A. bored .100" over with Snyder 5.5 to 1 head. A lot of variables I haven't listed but I'm running Champion 3X plugs I've gapped to .030" as I've read the for the higher comp. head to gap them at .030".
Anyhow, on Champion's website it lists the plug part # 561 as the W16Y with a temp rating of 16. The #518 plug: W18 is listed with a temp rating of 18. The W18 is a hotter plug which makes sense why many would say the W16y runs cooler. I'm going to purchase adapters from Bert's tomorrow and plugs locally and try the W16Y plugs. that along with some higher octane gas will hopefully solve my problem and then I can narrow things from there.
Anyhow, on Champion's website it lists the plug part # 561 as the W16Y with a temp rating of 16. The #518 plug: W18 is listed with a temp rating of 18. The W18 is a hotter plug which makes sense why many would say the W16y runs cooler. I'm going to purchase adapters from Bert's tomorrow and plugs locally and try the W16Y plugs. that along with some higher octane gas will hopefully solve my problem and then I can narrow things from there.
Y-Blockhead
Well-known member
You don't need adaptors to run Champion W16Y or W18s in a Snyder's head.
Also you don't need as much timing advance with a high compression head and you do with a stock head.
Thank you, I thought I needed the adapters. I'll try the w16y plugs and see if there's a difference. Also going to run 91 unocal in it as well. I am getting some bad knocking at higher rpm if I give it full throttle. Adjusting advance doesn't really make a difference., actually retarding it a bit while decreasing throttle will make the knocking go away
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My engine was rebuilt by Bert's in Colorado last year. I'm up to 1400 miles on it. I'm good at setting engine timing and did a great job rebuilding my carb. I learned to flow and adjust the flow on jets. I used Pargeter's book for my flow rates. A few guys from the Santa Anita A's heard it idling and running (just in a parking lot) last weekend and thought it ran very well.