Read my plugs please
12-18-2018, 06:15 PM
#1
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Read my plugs please
I have a recent build, N/A 400 sbc, about 30 hours. Was a new build from a previous motor that failed most likely due to detonation.
I installed O2 sensors in each riser and a wideband. I am currently running timing at 34 deg and my AFR readings I think/thought were pretty good. But after pulling a few plugs, I am thinking I am running lean.
SBC
Dart SHP block
402 CI
JE 2618 dished pistons (9.1:1 CR)
Crower rods
Crower crank (internal balanced)
Profiler 185cc heads (Ferrea super alloy exhaust valves/comp plus intakes. Pac beehive springs)
Comp Cams (270HR-12, 218 int./224 exh. 112 LSA)
RPM Airgap
Quick Fuel 650 DP
DUI HEI distributor (Timing set at 34 btdc all in at 3k)
What are your thoughts on these plugs?
Thanks,
Jim
I installed O2 sensors in each riser and a wideband. I am currently running timing at 34 deg and my AFR readings I think/thought were pretty good. But after pulling a few plugs, I am thinking I am running lean.
SBC
Dart SHP block
402 CI
JE 2618 dished pistons (9.1:1 CR)
Crower rods
Crower crank (internal balanced)
Profiler 185cc heads (Ferrea super alloy exhaust valves/comp plus intakes. Pac beehive springs)
Comp Cams (270HR-12, 218 int./224 exh. 112 LSA)
RPM Airgap
Quick Fuel 650 DP
DUI HEI distributor (Timing set at 34 btdc all in at 3k)
What are your thoughts on these plugs?
Thanks,
Jim
12-18-2018, 07:23 PM
#3
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Reading plugs with the junk none leaded fuel we have today is almost impossible to do accurately. You need to bring the engine up to temp change the plugs run WOT cut engine remove plugs. You now have something to read.
your have to cut the threaded part off and look at the ring at the bottom of the center ceramic. But if you have wide band what are your AF ratio that will give you a much clearer idea of what's going on.
your have to cut the threaded part off and look at the ring at the bottom of the center ceramic. But if you have wide band what are your AF ratio that will give you a much clearer idea of what's going on.
Last edited by Camalot; 12-18-2018 at 07:29 PM.
12-18-2018, 08:19 PM
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Reading plugs with the junk none leaded fuel we have today is almost impossible to do accurately. You need to bring the engine up to temp change the plugs run WOT cut engine remove plugs. You now have something to read.
your have to cut the threaded part off and look at the ring at the bottom of the center ceramic. But if you have wide band what are your AF ratio that will give you a much clearer idea of what's going on.
your have to cut the threaded part off and look at the ring at the bottom of the center ceramic. But if you have wide band what are your AF ratio that will give you a much clearer idea of what's going on.
Here are my AFR numbers before I re-jetted,
in gear:
650 (Idle) 13.2
1500 13.2
2000 13.4
3000 13.6
3600 13.9
4000 12.5
5100 WOT 12.8-13
I haven't written down my readings after the re-jet but I went up two sizes on both the primary and secondary's to get the numbers down some, which got most of the numbers down to the high 12's/low 13's. Idle out of gear is about 14. I will have to do write down some more readings on my next run. I was just concerned when I pulled those plugs and saw bright white and the deposits, haven't seen that before.
Jim
12-18-2018, 11:06 PM
#8
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Always read airgap intake is notorious for this however never confirmed. Might wanna do some staggered jetting but stop running asap. I might have missed as it's late but what heat range plugs? NA I've always had the best luck with mr43ts. Take a look at your pistons and cylinders with a bore scope. Every cylinder.
Charter Member
12-19-2018, 12:45 AM
#10
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looks like some sort of deposit on the plug,did it run hot?the afr,s are a little lean,i normally shoot for 12.5-1 on n/a engine.looking at piston tops with a bore scope should be the next thing you do.just curious,what fuel are you running?edit in,did you put a lot of anti seeze on the sparkplug threads when you installed them that chit detonates like a monster.
Last edited by mike tkach; 12-19-2018 at 12:50 AM.
