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Discussion Starter #1
On E85(instead of VP C12) the car picked up over a full tenth N/A and got it's best time with a 63N pill in the plate as well. I left the timing the same (locked at 36) and pulled 8 degrees with the juice flowing. Fuel pressure is 5.5 flowing and jetting is 63N 63F. AFR's are 11.8-12.0 on the gas scale with the nitrous on. Plugs are NGK 8's.

I'm having a hard time telling where the timing mark is on these plugs. The plug closest to the corner of the table has 2 nitrous passes then one n/a pass. The other plug as 2 nitrous passes. There are some black carbon specs on the porcelain. I'm guessing this is from driving back to the pits. Can anyone tell me where they see the timing mark? The way I'm seeing it the mark is at the beginning of the bend.





 

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Reading plugs will pretty much tell you what was happening inside the cylinders at the exact moment you shut the engine off . So if you made a run and then idled back to the pit area , the plugs will show what was happening at 1500 rpm . If the plugs were in the engine with a different fuel , some of what you see could simply be left over from the previous fuel . But what was happening at 1500 RPM isn't going top be much value in tuning the engine . Or what was happening with the other fuel . The plugs can still warn you of impending engine damage from detonation , but can't give you much info for what you need to change .
But for tuning info , you want to know what was happening at the finish line , or at the point where the engine was doing the most work at the highest RPM . That means installing new plugs and then making a full out run . As you cross the finish line , shut the engine off while under full throttle and then coast/get a push back to your pit area . Then pull the ALL of the plugs and inspect them . That will give the info you need to tune it .
 

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Discussion Starter #3
I could definitely be wrong here but I don't think the timing mark could move idling back to the pits? That is really what I'm looking for here. Agreed on everything else.
 

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Discussion Starter #4
Just to clarify these were fresh plugs. One has 2 passes, the other has 3.
 

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Discussion Starter #5
Here are some from the top end of the track. With my car's hydroboost brakes I have to leave it running to have any brake assist so shutting down at 120mph would be a bit hairy. It was shut down as soon as I turned off the track. I realize that this is not ideal.


 

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Only way to read a plug and see whats going on it to kill it as soon as you cross the line and pull it back. Any other way your just wasting your time.
 

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Discussion Starter #8
If these reading are worthless that sucks. I'll go do some more testing today. Am I even looking at the right line on these plugs? I'm trying to get a handle on exactly what the timing mark look likes, even it these photos don't reflect the tune at all.

 

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Discussion Starter #9
What's the combo? IMO tune up is fat.
Its an Edelbrock Performer RPM plate on 383 sbc. 63N 63F at 5.5psi on E85. 950 psi bottle pressure. Here is the long version of the car setup....

1984 Buick Regal
383 sbc
Forged flat top pistons w/2 valve reliefs
Engine Quest Heads. 200cc intake runners, 64 cc chambers
Crower Solid Roller 00426S grind
ADV Duration 288/290 Lift .570 .584
Duration @ .050 250/252
108 Lobe Center
Horsepower Innovations 750 Ultra HP E85 carb
Victor JR intake
Hooker headers, small primaries, 3" collectors
3" dual exhaust w/x-pipe, no cats, mandrel bent
700R4 Trans -built
JW Custom 4000 Stall 10" w/full size lockup plate.
4.11 Gears
27x11.50x15 Hoosiers
Car weighs 3390 lbs
Edelbrock nitrous plate system
Accel Nitrous Mastermind pulling 8 degrees timing
Distributor locked at 36 degrees
 

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Onpy way to see the timing mark and fuel ring from the pass there cant be any run time on the plugs after the pass. You will be able to see it if you do it this way tow it back or do it at the end of the track.
 

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What was the A/F on the motor pass? Looks to me like you are close. Mine runs a little faster at 12.2 or 12.4 A/F vs. 11.8.
Do you flow the fuel system with a gauge to set pressure?
I wonder about the A/F spike on the hit.. do you delay one or both solenoids?

Killing the engine in high gear can cause transmission problems. Not worth it in my opinion.
 

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Discussion Starter #13
What was the A/F on the motor pass? Looks to me like you are close. Mine runs a little faster at 12.2 or 12.4 A/F vs. 11.8.
Do you flow the fuel system with a gauge to set pressure?
I wonder about the A/F spike on the hit.. do you delay one or both solenoids?

Killing the engine in high gear can cause transmission problems. Not worth it in my opinion.
I set the fuel pressure flowing through the whole system into a bucket. It always reads about .25 psi higher on the logger than the gauge even though they both run off the same sender. I have verified accuracy with a mechanical gauge as well. I have a fuel pressure gauge right under my tach so I can watch it during the pass.

I'm a little leaner on the N/A side running 12.7-12.8 AFR at WOT.

I was wondering what a 120mph shutdown would do to my 700r4...

I have the nitrous coming on 100% at 3500. No delay, but there is an offset setting I can play with on my progressive. Haven't messed with it yet.

I'll use the progressive function if it is more than a 63N jet, but in this case it wasn't.
 

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I would say the timing mark is being blocked in the first photo. The shot where it can be seen, show's excessive lead and the purple hue on the ground strap confirms that cyl has seen a bit too much heat.
 

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Discussion Starter #17
I would say the timing mark is being blocked in the first photo. The shot where it can be seen, show's excessive lead and the purple hue on the ground strap confirms that cyl has seen a bit too much heat.
By too much heat are you thinking the NGK 8's aren't cold enough? I've got plenty of 9's on hand as well.
 

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Discussion Starter #20
Is it best to read the plug exactly as it comes out of the cylinder or brake clean it off first? I've noticed most of the remaining cadmium coating will wipe right off after a pass or two. Should it be cleaned or read exactly as is?
 
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