Spark Plug

54Hollywood

Our Hornet needs new plugs and I usually install Champion H-10C's because I can't find H-11's. Are the H-12's a closer heat-range match for the Hornet or what other plugs would any of you recommend and why? Thanks.



Tim in Wisconsin

Unknown

I'd try to find Autolite plugs since Champions have been so bad for so long.

Unknown

The H-12's are hotter than the H10C and H-11, but should be fine. The Autolite equivelent for an H-12 is 437. Some prefer using hotter plugs with today's gasolines.

[Deleted User]

54Hollywood wrote:

Our Hornet needs new plugs and I usually install Champion H-10C's because I can't find H-11's. Are the H-12's a closer heat-range match for the Hornet or what other plugs would any of you recommend and why? Thanks.



Tim in Wisconsin

Walt here. Go to any lawn mower store or Target or K-Mart and you will find your H-10 spark plugs. Do not install those hot plugs as todays gas burns hot and you can burn your valves and melt the plugs. If you just drive to the corner store, it's OK but not for any long trips.

[Deleted User]

You can buy H-10 at your local Napa. They always stock them.

Unknown

Using a plug that's the next range hotter is suggested to keep them from fouling, especially if your engine is using oil or running rich. On the flip side, cooler plugs are less prone to overheating and preignition in a "High Compresssion" engine or one that is run at prolonged high speeds. Hotter plugs are typically suggested for engines that don't see much high speed driving. Back in the days of leaded gasoline, it seemed that the lead was drawn toward the hotter (nose core) part of the plug. This caused glazing because the spark ran down the nose core instead of jumping the gap. So, going with a colder plug was the solution. With today's cleaner-burning oxygenated unleaded gas, many spark plug manufacturers suggest that old engines (those designed to use leaded gas) need to use plugs that are 1 to 2 heat ranges hotter than originally specified and have changed their catalogs accordingly.

SuperDave

I agree with MOST of what has been posted here. To add my thoughts...The heat range of the plugs is a function of the distance from the electrode to the cylinder head. It is not a measure of the combustion chamber temperature, nor does it have much effect on it. That is a result of the mixture and fuel formula. If the electrode extends further into the combustion chamber, the heat has to travel further to be cooled by the contact with the head. Since the heat has to travel further, the electrode will operate at a higher temperature. That does help to reduce fouling of the plug. Too high a PLUG temp will burn the plug and cause it to fail to burn the fuel. So as Dave53-7C said, an engine that has a lot of oil mist or a mixture that is too rich, needs a hotter plug. An old rule to remember is. A cold running engine needs a hotter plug, and, a hot running engine needs a cooler plug. If you make a lot of short trips and don't get the engine up to full temperature, Have a rich mixture, use a hotter plug.

Just changing the heat range of a plug to address the burning or fouling of a plug is only half the equasion. Reading a plug is a little more difficult today since the fuels have been reformulated. Perhaps the carburetor mixture needs to be adjusted? Also, to get a true reading on a plug, A new plug should be installed, The engine brought up to temperature by driving it at highway speed for several miles. Disingage the clutch, shut off the ignition and after pulling to the side of the road, remove the plug and read it. Just the few seconds of ideling the engine after a run, will skew your results. Most Hudson carburetors have worn metering rods and are running way too rich. It's a lot more difficult to adjust the high speed mixture than it is too change plugs, but is the correct way. Just don't lean the mixture out too much. That CAN raise the combustion chamber temperature to a point where the exhaust valves can't transfer their heat and then you WILL have burned valves and seats. Given a choice, I would run a little rich and set the valves a bit loose as Walt does.

464Saloon

I run NGK's, I have always had good luck with them in all my cars and bikes.

Unknown

464Saloon wrote:

I run NGK's, I have always had good luck with them in all my cars and bikes.

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What number ?

54Hollywood

As always, some terrific information from the Hudson clan! Thanks for all your responses. The car does run a bit rich and I don't do a lot of highway driving which is why I thought maybe an H-12 might work, or be more appropriate for a Hornet, instead of the H-10C. But I think I'll stay with the H-10C's and trouble shoot the carbs. The Twin-H on our 308 has the 968S carbs and I don't have a uni-syn (yet) so it'll be twice as much fun playing with the dual Carters. Thanks again.



Tim in Wisconsin

SuperDave

54Hollywood wrote:

As always, some terrific information from the Hudson clan! Thanks for all your responses. The car does run a bit rich and I don't do a lot of highway driving which is why I thought maybe an H-12 might work, or be more appropriate for a Hornet, instead of the H-10C. But I think I'll stay with the H-10C's and trouble shoot the carbs. The Twin-H on our 308 has the 968S carbs and I don't have a uni-syn (yet) so it'll be twice as much fun playing with the dual Carters. Thanks again.



Tim in Wisconsin

Set your floats to 5/8" instead of the 1/2" in the book..That might help s rich idle problem with the new fuels.

[Deleted User]

54Hollywood wrote:

As always, some terrific information from the Hudson clan! Thanks for all your responses. The car does run a bit rich and I don't do a lot of highway driving which is why I thought maybe an H-12 might work, or be more appropriate for a Hornet, instead of the H-10C. But I think I'll stay with the H-10C's and trouble shoot the carbs. The Twin-H on our 308 has the 968S carbs and I don't have a uni-syn (yet) so it'll be twice as much fun playing with the dual Carters. Thanks again.



Tim in Wisconsin

Keep that float at 1/2 inch and set the metering rods to factory specs. If not set correctly you can run rich or lean, bad news. 5/8 inch can cause starving going up steep grades and motor getting hot. Also on a sharp turn the engine can stumble. Walt.

Park_W

With all the Twin-H Hornets out there, has one of our enterprising folks come up with an accurate way to check the metering rod height? Even having the factory dimension doesn't help a lot without the exact shape of the lower end of the factory gauge. I tried to buy an original gauge not long ago, and the supplier wanted something like $40 for it. A gauge for the WDOs and WGDs would be welcomed as well.

dover1

Park, I have all the metering rod setting tools for Hudson Carter carbs. I would be happy to loan them to Hudson members who promise to return them in a prompt amount of time. I can be contacted in the forum or my info is in the club roster. buzz

hudsn47

I found this old post on spark plugs. Is the H-10 good for a 232? Thanks.

[Deleted User]

H-10s work just fine

hudsn47

Thanks!

Hudson Grandpa

My mechanic says, and I do, 1 bottle of Gunk Lead Substitute in the tank, with every 20 gals.

Anybody have any input on that? Mines a new engine.

hudsn47

I have used it in the past but I dont think its essential. Most people will use marvel oil as an upper cylinder lubricant or stabil as a stabilizer or both. If the car sits alot most recommend using stabil.