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Old 09-21-2022, 04:57 PM
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Just had this motor rebuilt and pulled the plugs after a few outings. #2 clearly looks rich and #7 not as bad, the others look okay to me, but what do I know.

Running a 1050 dominator. What carb settings could I look at to lean up #2 a little and #7? These were pulled after a 30 miles trip at good RPM with a little idle when trailering. I'd think they're pretty representivive. I checked timing and I'm showing 40* all the way up to 5000rpm. I'm supposed to drop it back by for them to check with their gun, but I think it's about 6* too high. They told me should be 34* above 5000. This is one of the reasons I decided to pull plugs to see if they were loose or any signs of detonation.

https://flic.kr/s/aHBqjA81HD

Thanks,
Todd
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Old 09-21-2022, 06:54 PM
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40*!!!!

That sound like a lot of timing to me.....

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Old 09-21-2022, 07:03 PM
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Originally Posted by seafordguy View Post
40*!!!!

That sound like a lot of timing to me.....
it sure does and the shop is stringing me along versus just verifying it. Thats another story. I just got the motor back so I dont want to make any changes at this point. This is how they gave it to me. Engine was apparently on the dyno as well, so not sure how were 6* off. I dont feel safe driving it with potential
for detonation.

they told me it should be 34* above 5k RPM what about 3-4900 RPM where it spends 90% of its life.
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Old 09-21-2022, 07:07 PM
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Looking thru my phone my eyes went to cyl #6 for now.
Appears to me like many pepper marks.

Detonation shows up on the plugs as spotting on the porcelain. There are two different types of spotting seen. One type appears as just black spots and the other appears as little bright spots like diamonds. The black spots (look like pepper sprinkled on the plug) indicate a little too much heat on the plug which causes detonation by having the heated plug fire off the mixture prior to the spark firing. This creates two flame fronts that collide and can cause great amounts of damage. If you see black spots on the porcelain and you know the tune-up is correct then you may need a colder plug. If you are not sure then increase the carburetor jet size slightly, take out some timing, or go to a colder plug. If you hold the plug in the sun and you see what appears to be small diamonds on the porcelain then your detonation is severe enough to be blowing off the aluminum from your piston and you need to add fuel and/or take out timing now.
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Old 09-21-2022, 07:26 PM
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Originally Posted by SB View Post
Looking thru my phone my eyes went to cyl #6 for now.
Appears to me like many pepper marks.

Detonation shows up on the plugs as spotting on the porcelain. There are two different types of spotting seen. One type appears as just black spots and the other appears as little bright spots like diamonds. The black spots (look like pepper sprinkled on the plug) indicate a little too much heat on the plug which causes detonation by having the heated plug fire off the mixture prior to the spark firing. This creates two flame fronts that collide and can cause great amounts of damage. If you see black spots on the porcelain and you know the tune-up is correct then you may need a colder plug. If you are not sure then increase the carburetor jet size slightly, take out some timing, or go to a colder plug. If you hold the plug in the sun and you see what appears to be small diamonds on the porcelain then your detonation is severe enough to be blowing off the aluminum from your piston and you need to add fuel and/or take out timing now.
Great eye. It even looks like the electrode is worn down compared to the others. This has maybe 5-10
hours on it.
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Old 09-21-2022, 07:50 PM
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40* is crazy. Must be a light boat, don`t think 40* at peak cylinder would last 10 minutes in my tank.
I`m running closer to 26-28* depending on boost.
You need to get that sorted asap.
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Old 09-21-2022, 07:57 PM
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Yup.
That was discussed on his other thread. Not sure why this thread (id suspect some detonation) as his type heads and compression typically use 34-35 degrees.
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Old 09-21-2022, 08:06 PM
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Originally Posted by ICDEDPPL View Post
40* is crazy. Must be a light boat, don`t think 40* at peak cylinder would last 10 minutes in my tank.
I`m running closer to 26-28* depending on boost.
You need to get that sorted asap.
Yes this is NA at least but still. Shops telling me it was set at 34, my gun shows me 40. Im a technology guy, so I trust the guys that have been doing it for 30 years, but something seems off. This is a big miss for them if the timing is actually at 40*.

Little things like a faulty fuel pressure gauge they didnt change, but knew was was bad. That caused me a day troubleshooting on the water, getting parts, only to find out they knew the gauge never worked. Missing nut that connects the lower/upper drive. Little things that make me lose confidence in what they delivered.
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Old 09-21-2022, 08:08 PM
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Originally Posted by SB View Post
Yup.
That was discussed on his other thread. Not sure why this thread (id suspect some detonation) as his type heads and compression typically use 34-35 degrees.
Not trying to duplicate posts and issues here - Im not worried about my post count 😂

Really wanted an opinion on what you all thought on the plugs. Doesnt change the timing issue I think is going on.
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Old 09-21-2022, 08:14 PM
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All good. Round table talk.
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