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| Later Model Heads NGK UR-4 or UR-5? https://www.slantsix.org/forum/viewtopic.php?t=29202 |
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| Author: | bwhitejr [ Thu May 29, 2008 4:24 am ] |
| Post subject: | Later Model Heads NGK UR-4 or UR-5? |
I am running 9.XX:1 compression on my 1980 truck and want to replace my Champions. Which NGK UR-4 or UR-5? bwhitejr |
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| Author: | DusterIdiot [ Thu May 29, 2008 5:31 am ] |
| Post subject: | Either... |
Both will fit, UR-5 will be cooler than the UR-4, so i you have any fouling issues the '4' would be a better choice... you can always start with the 5's and see if the plugs are a good color, if they are a bit black then you can move up to the 4... -D.Idiot |
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| Author: | SlantSixDan [ Thu May 29, 2008 5:32 am ] |
| Post subject: | |
The UR4 is a little hotter-running plug, the UR5 a little cooler. You may want to try the UR5 first, since a cooler-running plug will buy you some room for more timing advance before you get ping. But pull and check a couple of them after you've run them for awhile; if they're not running clean you'd want to bump up to the UR4. (d'oh...sorry for the incorrect initial post. DI is correct; in the NGK plug numbering system a higher number means a cooler spark plug.) |
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| Author: | Aggressive Ted [ Thu May 29, 2008 11:16 am ] |
| Post subject: | |
For reference: I am running the NGK UR4 in my 9.5 to 1 rebuild and they are coated with a very light cinnamon color at 30,000 miles. I am running 16 degrees initial advance with 16 mechanical and a .040 gap with no ping, on Cenex gas. |
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