General plug reading/ opinions
11-04-2011, 10:14 PM
#1
General plug reading/ opinions These are TR6, gapped .045" and have been in about 1800 miles. My SCR is right at 11:1, making about 440 FWHP. To me, they look wet and a little fouled. I think I went too cold, should have stayed with TR55s. Before I go back to TR55s at .048" I wanted to get some general feedback. There is no seepage from the FPR, tune is a little fat and has a fair amount of timing (need to read the tune and update here to see if maybe it's too fat/ too much timing period). I've started having a little hesitation at part throttle/ under acceleration lately so I started by looking at the plugs. first 2 pics are 1-3-5-7, 2nd 2 pics are 2-4-6-8.
11-04-2011, 10:52 PM
#2
Launching!
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1st thing is to look down into the insulator, not at the top near the electrode.
Just glancing at the pics, which are not at the angle I need to see, two of your cylinders are running slightly rich.
No bad but richer than the others. ( 1,3,4,6)
The timing is cooking a few plugs, (1 and 4)
If you want to run that timing, you can lean it out a tad but make sure your injectors are all firing with the same pattern and volume.
I personally don't like those plugs.
Try Denso double platinum or their Iridiums if you have the cash.
No finer plug I have found has a wider heat range and still has a good life rate under anything short of a sprayed blower application.
Just glancing at the pics, which are not at the angle I need to see, two of your cylinders are running slightly rich.
No bad but richer than the others. ( 1,3,4,6)
The timing is cooking a few plugs, (1 and 4)
If you want to run that timing, you can lean it out a tad but make sure your injectors are all firing with the same pattern and volume.
I personally don't like those plugs.
Try Denso double platinum or their Iridiums if you have the cash.
No finer plug I have found has a wider heat range and still has a good life rate under anything short of a sprayed blower application.
11-06-2011, 08:12 PM
#5
Launching!
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Yup, a few cylinders are running rich for some reason.
Don't know if this motor's piston / ring set up is good all the way around.
Could be more wear in a few cylinders.
Still, you should be seeing more lighter brown fading to light from the base ceramic to the electrode.
IMO, the timing / mixture is not correct for the cylinder pressure that this motor is developing, at least in a few cylinders.
This is a liquid cooled motor so the variations from cylinder to cylinder should be a lot closer.
This kind of thing happens frequently with V twin air cooled engines, with the rear cylinder showing a rich condition compared to the leading cylinder.
Basic difference being the rear barrel gets hotter due to less air flow around it and causes the cylinder to expand more for less sealing.
So that being said, I would start from the injection system to match the injectors, then check the cam timing along with the ignition timing.
Run the engine a bit then do a compression check on every cylinder to see how close they are.
Don't know if this motor's piston / ring set up is good all the way around.
Could be more wear in a few cylinders.
Still, you should be seeing more lighter brown fading to light from the base ceramic to the electrode.
IMO, the timing / mixture is not correct for the cylinder pressure that this motor is developing, at least in a few cylinders.
This is a liquid cooled motor so the variations from cylinder to cylinder should be a lot closer.
This kind of thing happens frequently with V twin air cooled engines, with the rear cylinder showing a rich condition compared to the leading cylinder.
Basic difference being the rear barrel gets hotter due to less air flow around it and causes the cylinder to expand more for less sealing.
So that being said, I would start from the injection system to match the injectors, then check the cam timing along with the ignition timing.
Run the engine a bit then do a compression check on every cylinder to see how close they are.
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11-06-2011, 09:21 PM
#8
Actually, no, you can't.
If the car is rich at one point in the RPMs it will pollute the plug so you can't tell what's going on.
First of all the car needs the idle, and mid range tuned, then WOT can be tuned by reading the plugs and the aide of a wideband.
If the car is rich at one point in the RPMs it will pollute the plug so you can't tell what's going on.
First of all the car needs the idle, and mid range tuned, then WOT can be tuned by reading the plugs and the aide of a wideband.
11-06-2011, 11:30 PM
#9
Launching!
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Your wrong so don't try to wiggle out of your statement.
Piston to wall clearance makes a big difference on how a cylinder operates.
Even in highly tuned engines, plugs are positioned with electrodes in facing certain valves to eliminate differences.
He has no idea what is causing his plug differences.
You assume too much.
Piston to wall clearance makes a big difference on how a cylinder operates.
Even in highly tuned engines, plugs are positioned with electrodes in facing certain valves to eliminate differences.
He has no idea what is causing his plug differences.
You assume too much.
11-07-2011, 08:14 AM
#11
Thanks for the responses. The story on the tune is that it was done by a guy I went with on a friend's recommendation (personal friend). The tune was done with #6 touching the wire on a primary and an opti that blew up 100 miles later, so I've always wondered how far off the tune would be. I've wanted to take it back and have him completely redo the tune. The part throttle has never been great and the transitions from CEL 16-17-18 probably needs a lot more smoothing. My gut tells me to sever the relationship and find a new tuner. Or continue learning and fix it myself. I don't know if he locks his tunes or locks the PCM like some tuners do. I'm using Tunerpro to try and pull the tune one day this week. Finally got the ALDL cable and been reading a lot.
It's not all bad, it just needs to be better. This was my first LT1 buildup after plenty of old SBCs and I'd have done a lot of things differently if I knew then what I know now. And now PCMforLess is dyno tuning LT1s again in Mooresville (less than 2 hrs away). There's also the temptation to start over but I got married and have a kid on the way so no forged 383 this year.
It's not all bad, it just needs to be better. This was my first LT1 buildup after plenty of old SBCs and I'd have done a lot of things differently if I knew then what I know now. And now PCMforLess is dyno tuning LT1s again in Mooresville (less than 2 hrs away). There's also the temptation to start over but I got married and have a kid on the way so no forged 383 this year.
11-07-2011, 09:22 AM
#12
you need to make a WOT pull then look at the plugs right after.........but looking at these i can make these ball park readings...........
1. Part throttle fueling is too rich
2. Possibly a bit too much timing in the motor but kina hard to read from the pics
3. Heat range is on the border........IMO id stay with the TR6
WOT fueling must be read one of two ways.......cut the threads off the plug to see the bottom of the ceramic or two get a magnifier kit so you can see it with a light
1. Part throttle fueling is too rich
2. Possibly a bit too much timing in the motor but kina hard to read from the pics
3. Heat range is on the border........IMO id stay with the TR6
WOT fueling must be read one of two ways.......cut the threads off the plug to see the bottom of the ceramic or two get a magnifier kit so you can see it with a light
11-07-2011, 10:41 AM
#15
1st thing is to look down into the insulator, not at the top near the electrode.
Just glancing at the pics, which are not at the angle I need to see, two of your cylinders are running slightly rich.
No bad but richer than the others. ( 1,3,4,6)
The timing is cooking a few plugs, (1 and 4)
If you want to run that timing, you can lean it out a tad but make sure your injectors are all firing with the same pattern and volume.
I personally don't like those plugs.
Try Denso double platinum or their Iridiums if you have the cash.
No finer plug I have found has a wider heat range and still has a good life rate under anything short of a sprayed blower application.
Just glancing at the pics, which are not at the angle I need to see, two of your cylinders are running slightly rich.
No bad but richer than the others. ( 1,3,4,6)
The timing is cooking a few plugs, (1 and 4)
If you want to run that timing, you can lean it out a tad but make sure your injectors are all firing with the same pattern and volume.
I personally don't like those plugs.
Try Denso double platinum or their Iridiums if you have the cash.
No finer plug I have found has a wider heat range and still has a good life rate under anything short of a sprayed blower application.
Your wrong so don't try to wiggle out of your statement.
Piston to wall clearance makes a big difference on how a cylinder operates.
Even in highly tuned engines, plugs are positioned with electrodes in facing certain valves to eliminate differences.
He has no idea what is causing his plug differences.
You assume too much.
Piston to wall clearance makes a big difference on how a cylinder operates.
Even in highly tuned engines, plugs are positioned with electrodes in facing certain valves to eliminate differences.
He has no idea what is causing his plug differences.
You assume too much.
11-07-2011, 11:56 AM
#16
These 'Platinum TT' Denso plugs are 2.99/ea at Advance Auto so I'm giving them a shot. They'll at least last long enough to do some data logging, I'd think.
11-08-2011, 10:51 AM
#17
Butt dyno says the Denso plugs at .048" work very well, throttle response is very crisp from idle in CEL 16 with hard stabs through 17-18. I still notice that part throttle cruising feels a touch off between 2200 and 2800 RPM. I'm going to bet this is one place where I'll see too much timing and fuel. Wish I had more time last night. Only took 25 minutes to get the pass. plugs in with AIR fittings, dispstick tube and Canton covers. Got it almost down to a science. 
Sorry to be slow with progress in this thread. There's a lot (good) going on at home and work. I should be able to do some logging on Thursday night. And thanks again for the feedback.
Sorry to be slow with progress in this thread. There's a lot (good) going on at home and work. I should be able to do some logging on Thursday night. And thanks again for the feedback.
