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Old 01-24-2008, 08:31 PM   #1
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Default Glow plug cold temps

My engine (axxe rossi x1)was shipped with a very cold glow plug and I plan to race a indoor race with no heat. Probably the temp will be 30-40. There are four plugs made by the Axxe Rossi:

extra cold
very cold
cold
medium

with the cooler temps should i change to a warmer plug??

I run 30% fuel.

thanks
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Old 01-24-2008, 08:45 PM   #2
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Try the RT5 or RT6. (medium or cold) It really depends on engine once you start running it. I would say try the next heat range warmer first. Novarossi turbo plugs fit also and are the same heat range values.
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Old 01-25-2008, 08:08 AM   #3
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Quote:
Originally Posted by ezveedub View Post
Try the RT5 or RT6. (medium or cold) It really depends on engine once you start running it. I would say try the next heat range warmer first. Novarossi turbo plugs fit also and are the same heat range values.

Hi, I am new n the choosing glow plug. Can you please advise me when and why I have to use hot, medium hot or cold plug on my engine. I stay in Asia and weather is hot from 1st Jan till 31st Dec....... Pls advise. Thanks.
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Old 01-25-2008, 08:34 AM   #4
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I don't understand why manufacturers choose to label glow plugs cold and hot. It just doesn't make sense. What the different "temp" plugs are really doing is simply adjusting the ignition timing of the engine.

Engines with high compression ratios running high nitro % need a "cold" plug to keep them from detonating. (most race .21's)

Engines with lower compression and less nitro will use a hotter plug to advance the ignition timing to improve throttle response and ease tuning.

The outside temperature has very little to do with glow plug "temp." If anything, running in very cold temps might warrant a change to a colder plug. That is because cold air is more dense, which will effectively increase compression and advance the timing. Advancing timing too far will cause detonation and you will have to either run a colder plug or add head shims.

So to answer your question: Run the very cold plug it came with. And since it's brand new make sure to heat it with a heat gun to at about 180-200 degrees before you put it on the starter box.
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Old 01-25-2008, 11:33 AM   #5
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Quote:
Originally Posted by gubbs3 View Post
I don't understand why manufacturers choose to label glow plugs cold and hot. It just doesn't make sense. What the different "temp" plugs are really doing is simply adjusting the ignition timing of the engine.

Engines with high compression ratios running high nitro % need a "cold" plug to keep them from detonating. (most race .21's)

Engines with lower compression and less nitro will use a hotter plug to advance the ignition timing to improve throttle response and ease tuning.

The outside temperature has very little to do with glow plug "temp." If anything, running in very cold temps might warrant a change to a colder plug. That is because cold air is more dense, which will effectively increase compression and advance the timing. Advancing timing too far will cause detonation and you will have to either run a colder plug or add head shims.

So to answer your question: Run the very cold plug it came with. And since it's brand new make sure to heat it with a heat gun to at about 180-200 degrees before you put it on the starter box.
That can be true, to a point. In cold enough weather, the idle may suffer with a cold plug, so going one heat range warmer will help. It will detonate if its hot enough, but if the engine runs cool enough, you can use a hotter plug and take advantage of the denser cooler air. Also, you will have to richen the mixture up also in most cases for this condition. If you stick to cold plug with richer fuel mixture and dense air, you may ignite too late as there is more fuel mixture to burn and you will blow it out the exhaust port. I prefer cold style plugs myself and I only toggle between #6 or #7. Rarely do I use a 5 on a an italian engine. If this was an O.S. engine running P3, i may go to a P4, but thats it. Also, for new engines, I will sometime install a hotter plug so it will stay running better for break-in with rich mixture and the tightness in the engine. In general. I will use a plug that works best for me and the tuning of the engine, so don't just change plugs because of ambient temps. Run what is comes with and only move one or maybe two heatranges in either direction to see what your results are. Also shim as need for nitro. The Axe Rossi Cobra X1 I believe is good stock shimmed for 30%, or shim it for head to button clearance or 0.026-.030 in for deck clearance for 30% nitro with a #7 or #6 glowplug. The Mamba can go tighter, but thats do to a dished and broader piston. Always check your engine for any signs of detonation once you make any changes like this though.
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Old 01-25-2008, 01:03 PM   #6
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I just use regular O.S. #8 plugs. I live in Canada, so it's cold...
I really don't have any problems at all with regular #8's.

You do not need to change plugs for outside temps. You must pre-heat the engine and tune (Richer). and make an effort to keep temps up (tin foil on head and throttle use, keep revs up).
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