Major disappointment

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Major disappointment

Post  6jeff6 on September 28th 2015, 7:19 am

Well the cobra did not perform well at all. Best time 12.032 @ 113.40 with 1.749 60 ft. It breaks up at 5,550 so I couldn't go to planned 6 grand to shift. I'm rained out today so I'll pull plugs but any ideas? I'm leaving at about 3,500 give or take a few rpm. I expected way more out of the 521
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Re: Major disappointment

Post  cletus66 on September 28th 2015, 8:00 am

There are always bugs to work out.  I picked up 8 tenths when I figured out my throttle wasn't opening all the way.  Embarassed

You definitely need to figure out that miss. Could be as simple as fouled plugs, depending on what you're running. Do you have an AF meter?
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 8:06 am

That's good to hear. Now I loosen the front band a little for more grab right? Just felt a little loose and pulled hard once going but I expected more of a shock with 3,500 stall.
Wish I could afford to get nos going as I think it's actually all set up to spray and why there is issues n/a but baby steps.
My biggest disappointment was mph that's low
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Re: Major disappointment

Post  D. Sea on September 28th 2015, 8:12 am

Details would help.
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 8:18 am

Car 97 cobra nice set up built 8.8 with spool will check gears today but when bought car said 3.73s or less, spool, 28x10x15 slicks, aluminum drive shaft, built c4 with 3,500 stall, bone stock 521 from roush/Yates with kooks headers that made 609 hp at 5750rpm with 1050 dominator carb.
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 8:23 am

10 gallon fuel cell in trunk with battery in trunk also. Full interior with welded roll bar. Full length race sub frames with axle girdle (I can't remember what it's called).
Ran almost straight turbo blue
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 8:36 am

Well may have found the issue there's a 2 step somewhere on the car and maybe they have Rev limit too low. Any hints on the 2 step? Peak torque is 4,500 with peak hp at 5,750.
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 9:11 am

2 step:
Start is at 10
Step retard little arrow is pointed at E 14.
This is PN 8987
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 9:32 am

Plug is really black. Maybe too much street idling ?
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Re: Major disappointment

Post  D. Sea on September 28th 2015, 12:42 pm

Sounds really rich OR you're driving down the track on the 2 step? Should be a few seconds quicker with that kind of power. In the 6's 1/8 and 10's 1/4 for sure IMO.
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 12:52 pm

I really don't know. How can I figure it out? I'm new to the 2 step
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 12:59 pm

I never hit the over rev/rev reduction peak at the line it was just quick rev to 3500ish and gone. So to test this just fire up car, put in 1st, hold trans brake, rev up and there should be a cut out/limiter and that's my first step?
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Re: Major disappointment

Post  FalconEh on September 28th 2015, 1:23 pm

The #8987 is not a 2-step it is a start retard / activation retard the way you have explained it the box is retarding the timing 10^ on start-up, the E14 setting would be retarding the timing 14^ on activation (14^ retard from total timing) Follow the pink wire from the 8987 box and see where it goes this wire should only be activated for a given amount of nitrous, if it is activating now you are removing 14^ of total timing.
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 1:43 pm

Pink wire goes by shifter into plug in, from there 2 go to button for reverse/trans brake, other two go back toward nitrous bottle in trunk
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 1:45 pm

Sorry they go to trans brake/reverse button
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 1:46 pm

And the other 2 go to nitrous button
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Re: Major disappointment

Post  FalconEh on September 28th 2015, 1:55 pm

It sounds like they have wired the retard box to activate on the release of the trans-brake put a timing light on the car and rev it until the total advance is in likely you will not have enough advance, if this is the case turn the knob to 0 and try it again the total timing should increase by 14^
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 2:00 pm

K I will have to wait until my son is home but if what you saying is right then if I fill bottle she's completely set up for the 125 shot?
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Re: Major disappointment

Post  FalconEh on September 28th 2015, 2:20 pm

6jeff6 wrote:K I will have to wait until my son is home but if what you saying is right then if I fill bottle she's completely set up for the 125 shot?

That would depend on other factors too, it would mean that the timing retard is set to activate on the release of the t-brake button with the number of degrees you set the dial to. As for the 125 shot that would depend on the jets that are in the kit, whether the full throttle activation switch is hooked up, etc. but yes the timing retard would be ready for nitrous use.
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 2:33 pm

From what the Jets are it's a 125 wet nos kit
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 2:42 pm

Now I have to depress and let go of trans brake when I do this to activate it right?
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Re: Major disappointment

Post  supervel45 on September 28th 2015, 3:21 pm

I would not start spraying it until you get everything lined out. You do not need to pull 14 degrees of timing out for a 125HP shot either. Good idea to have a timing light to check the electronics also.

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Re: Major disappointment

Post  supervel45 on September 28th 2015, 3:25 pm

http://www.jegs.com/InstallationInstructions/100/121/121-8987.pdf Here are the instructions for the MSD 8987 retard box.

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Re: Major disappointment

Post  FalconEh on September 28th 2015, 3:29 pm

6jeff6 wrote:Now I have to depress and let go of trans brake when I do this to activate it right?

No, just find the full throttle activation switch and close the loop (depress the switch arm with a zip tie or tape), the way it is likely wired is the nitrous will come on under full throttle by way of the full throttle activation switch, and the trans-brake will interrupt the nitrous under full throttle until the button is released.
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Re: Major disappointment

Post  6jeff6 on September 28th 2015, 3:37 pm

K I get it now thanks!
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