# Color-tune Spark Plug **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [July 3, 2023, 9:40pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494 "2023-07-03T21:40:03Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [July 3, 2023, 9:40pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/1 "2023-07-03T21:40:03Z")
I’ve seen reports of diy’ers using this product to fine-tune the idle rpm mixture, mostly on carbureted engines. It apparently allows you to actually look inside the cylinder as the engine runs, and you adjust the mixture to get a nice blue-looking flame, like if you were adjusting your natural gas stove. Does anyone here have any experience with this product? It seems like a good idea, but maybe there are some impracticalities? ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [July 3, 2023, 9:45pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/2 "2023-07-03T21:45:57Z")
It’s been around for decades. You can find out how to use it on YouTube. ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [July 3, 2023, 9:46pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/3 "2023-07-03T21:46:45Z")
I used to use those perhaps 55 years ago. While it worked nicely, I found I could get just as good an idle using my tach and a vacuum gauge, and it was quicker. I think I got it from J.C. Whitney ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [July 3, 2023, 9:52pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/4 "2023-07-03T21:52:11Z")
> [@old\_mopar\_guy](#): > > I found I could get just as good an idle using my tach and a vacuum gauge That’s how I do it now. I get a good idle in the sense that the engine idles smoothly even though I’ve adjusted the adjustment toward lean as much as possible. but I don’t really know if the idle mixture is correct or not. I tend to end up with the mixture adj screws 2 1/2 turns out, and some books saying 1 1/2 turns out is closer to correct mixture. ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [July 3, 2023, 11:14pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/5 "2023-07-03T23:14:34Z")
Don’t remember how I adjusted the carbs on the corvair but think I just used a vacuum gauge. ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [July 3, 2023, 11:26pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/6 "2023-07-03T23:26:33Z")
I would start with 1 1/2 turns out, and then adjust in or out to obtain the highest vacuum reading. I was never concerned if the mixture was stoichiometrically “correct” as long as i had a smooth steady idle at 550 rpm in drive. ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [July 3, 2023, 11:55pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/7 "2023-07-03T23:55:26Z")
I’d just adjust for leanest smooth low idle. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [July 4, 2023, 1:48am UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/8 "2023-07-04T01:48:21Z")
Good grief . . . ! 🙄 I haven’t heard anybody mention colortune spark plugs in DECADES 🤨 ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [July 4, 2023, 5:23am UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/9 "2023-07-04T05:23:00Z")
I’ve still got an old jc Whitney catalog. It’s fun to go through it sometimes just to see all the products like the pellets to bring back a dead battery. Never heard of those spark plugs though. Don’t know why I should have. ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [July 4, 2023, 2:23pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/10 "2023-07-04T14:23:48Z")
I don’t think Gunson is an American company . . . at least it doesn’t currently seem to be And their products are . . . for the most part . . . not professional quality, imo ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [July 4, 2023, 4:03pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/11 "2023-07-04T16:03:49Z")
I’ve never heard of them either and I have to very good friends that are in there mid 70’s with lots of old school tools and we have done a lot of tunning together and they have never mentioned to me nor used one around me, and I new there tool boxes very well… Not saying they never had or used one, just not that I saw or heard of… It sounds a lot like snake oil to me… lol ---
**Author:** ![jimkoe329\_179295](https://avatars.discourse-cdn.com/v4/letter/j/b77776/32.png) [@jimkoe329\_179295](https://community.cartalk.com/u/jimkoe329_179295)\ **Post date:** [July 4, 2023, 8:35pm UTC](https://community.cartalk.com/t/color-tune-spark-plug/191494/12 "2023-07-04T20:35:10Z")
I used color tune on many dual SU carb 4 cylinder engines many years ago.