7000RPM Guys - Blowing Out Spark?
06-12-2006, 02:02 PM
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7000RPM Guys - Blowing Out Spark? Guys that are turning 7000RPM on the stock shortblock - I need your help.
I'm running NGK TR55 plugs gapped at .055, and shifting ~6900RPM. In the neighborhood of 6600-6800RPM (both on the dyno and the street), there is a very slight miss that only lasts a split second. I think you can see it reflected in this dyno graph.
My tuner recommends tightening the gap to ~.045 and trying that, which I will. My question for you all is this: is there anything else it could be? I'm sure some of you have experienced something like this before.
The car has TSP's hardened pushrods, so I think we can eliminate a bent pushrod as a possibility. Any other ideas? Thanks in advance folks!
I'm running NGK TR55 plugs gapped at .055, and shifting ~6900RPM. In the neighborhood of 6600-6800RPM (both on the dyno and the street), there is a very slight miss that only lasts a split second. I think you can see it reflected in this dyno graph.
My tuner recommends tightening the gap to ~.045 and trying that, which I will. My question for you all is this: is there anything else it could be? I'm sure some of you have experienced something like this before.
The car has TSP's hardened pushrods, so I think we can eliminate a bent pushrod as a possibility. Any other ideas? Thanks in advance folks!
06-12-2006, 03:08 PM
#2
Im not a pro on high RPM stuff, but on my Lightning, at 14psi i was getting spark blowout, so i tightened the gap, and havent had a problem since. I dont see anything else causing the problem. If the tighter gap doesnt solve the problem, then id start looking at your coil packs.
06-12-2006, 03:28 PM
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with the graph smoothed on 5, its not easy to tell....if you can get it sans smoothing would be better. Other than spark blowout, what about valve springs? Ran mine up to 7300 TR6' gapped @ .032".
06-12-2006, 04:00 PM
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Originally Posted by CAT3
with the graph smoothed on 5, its not easy to tell....if you can get it sans smoothing would be better. Other than spark blowout, what about valve springs? Ran mine up to 7300 TR6' gapped @ .032".
Valve Springs are the Precision Race Components Double Springs rated to .660" lift (with Titanium Retainers, Spring Seats, Seals).
06-12-2006, 08:04 PM
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Thanks, just wanted to confirm it does not look like valve float. We had a couple guys on the rollers when I dyno'd mine that went into VF issues, very choppy. I agree with ^, shift earlier and try the regap out.
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06-12-2006, 08:52 PM
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I experience some valve train instability around 6800 rpms using PRC duals. I have been thinking of shimming them up some to help. I was running TR55s and also went to TR6s gapped at .035. havent hit the dyno again since the plug change. My graph was more choppy than yours up top, but honestly Im not too worried about it as well because my car makes peak power at 6250 rpms. 
Last edited by cantdrv65; 06-12-2006 at 09:04 PM.
06-13-2006, 10:24 AM
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I dont think i've ever had an issue with spark blowing out at 7100+ stock bottom end. I think I'm just looking for an excuse to build the engine...stupid Trex cam
06-13-2006, 12:29 PM
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Originally Posted by PREDATOR-Z
You are not benefiting by shifting that high. Cam is obviously dipping after 6500. so i would shift 6700 or so.
No need to kill your motor for nothing.
No need to kill your motor for nothing.
I will try shifting lower and seeing if that helps ET, but I very seriously doubt that the situation is as extreme as you make it sound.
06-13-2006, 08:43 PM
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Originally Posted by JoeyAnderson
So that extra 200RPM is "killing my motor"?
I will try shifting lower and seeing if that helps ET, but I very seriously doubt that the situation is as extreme as you make it sound.
I will try shifting lower and seeing if that helps ET, but I very seriously doubt that the situation is as extreme as you make it sound.
06-13-2006, 08:47 PM
#15
**** u guys are running tight gaps on ur cam cars. i didnt change the gap on my tr55's when i installed the torquer. they are at .50-.55. should i swap them out or tighten them up? maybe this attributes to my poor dyno some.
back to the question at hand i shift mine at 6700 and i dont think anything is wrong with it. atleast not that i can tell.
back to the question at hand i shift mine at 6700 and i dont think anything is wrong with it. atleast not that i can tell.
please explain. 
