Another nitrous question

Old 10-07-2008, 04:07 PM
  #11  
jwhitehead
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Default another nitrous question

I have a billet MSD dist. with MSD 7AL ignition.
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Old 10-07-2008, 04:26 PM
  #12  
bjuice
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the bg 400 pump is plenty..what is the fuel pressure dead headed at the motor?

how do you have the Nos plumbed..i understand you have a fuel log..but what is run off the log ? you got a 4 port regulator ??
you got a pic ?..


i think your gonna find your problem in One or both of these area's

1- timing retard
2- plugs either too hot and GAP wayyy too wide
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Old 10-07-2008, 04:26 PM
  #13  
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Carb sounds like an 8896, I would pull the power valves out and jet up to 93 to start along with the other suggestions. There are a few more things it needs, but I would start with that. Try making the motor run NA correctly before you add NOS or you will be chasing your tail.
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Old 10-07-2008, 05:40 PM
  #14  
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I agree with Brian you'll find it most likely in the timing retard is not working properly. I test all mine before I plan to use it.
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Old 10-07-2008, 09:57 PM
  #15  
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Default Re: Another nitrous question

Originally Posted by jwhitehead
have a 502 with a fogger, timing set @ 36, retard set @ 12, 1050 dominator with 88 front and rear jets,everything new, set up 300 shot, bottle full with 900 p.s.i. engine back fires thru headers , shut engine down. Checked plugs, electrode in porcelin on some plugs had started to melt.

set up 250 shot increased bottle pressure to 1100 p.s.i. car ran 1.16 / 60 foot, 5.38 @ 127 mph.

SB2 406 small block ran this good, what am I missing?????
first the botle pressure @900-psi is too low and will only get lower at the end of the run,as you use more nos.i would get it @ 1000-psi and purge it down to 950,at start of run so it should end @ 900psi with a 250-tune.1100-psi is too high.also a 250 shot at 28/28jetting is fat.you should look into the motor to see if you didn't damage it when you melted those plugs before you go any further because if you have some piston damage you will put oil into th motor and then bang.just my 02
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Old 10-08-2008, 07:26 AM
  #16  
gimmemud
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Default Re: another nitrous question

Originally Posted by jwhitehead
Thanks all,

the nitrous/fuel jets are 28/28 , the fuel pump is a BG 400 mounted at the front of the car plumbed with #12 an braided lines to a fuel log, #12 feed the carb and #10 feed the fuel solenoids.

You will see more power and way better response if you will go to a 28 fuel/ 32 nos jet spread and use 6 lbs of fuel pressure to start with, you may have to go up or down 1/2 lb to get it perfect but it will be a good start. Alco as Farigno mentioned get your bottle pressure up to 1000 psi and purge it down to 950 psi before the run. Those fuel lines are overkill, a 8an to the carb and 6an to the soleniods is plenty.
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Old 10-08-2008, 03:40 PM
  #17  
jwhitehead
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Default another nitrous question

wow, i never expected so many responses, Thanks for your help. Everything made sense to me with the exception about pulling out the power valves, why and should the holes be plugged or left open?

Also the fuel log is a BG, it has a built in reg. with multiple feed lines, I use one with a tee to feed the carb and the other has a tee and has a reg feeding the fuel solenoids. And of course the nitrous is fed from the bottle to the nitrous solenoids.
I can adjust the pressure at the log regulators or at the fuel pump. I can turn the pump on and the pressure is @ 10 psi , it doesnt deadhead because it has a return, I did block the return and the guages pegged out.

Now, based on your info, sounds like:
pull power valves and increase jet size
bottle pressure too low
timing retard not working
plugs too hot
plug gap too large
maybe change nitrous jets to 28/32??????? help

Did I miss anything?
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Old 10-08-2008, 05:16 PM
  #18  
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if i read your post right your fuel log is regulating the out ports of your fuel log and then you have another regulator to your Nos fuel...

if this is the case..this is BIG,BIG No-No...you do not supopose to regulate a line that is already regulated....this spells disaster.

You need your Nos fuel side fed straight from the fuel pump regualted one time..or take off the fuel log and run a regualtor that has a free flowing port...run the fuel lines to your motor and regulate off main regualtor..run the Nos fuel supply from FREE FLOW port to its own regualtor and test flow the Nos fuel from that Independent regulator. Holley silver regualtors are a popular choice of regualtors for dedicated Nos fuel feeds

bottom line regulate your Nos fuel 1 time

i hope that made sense ... :roll: ..lol
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Old 10-09-2008, 05:34 AM
  #19  
gimmemud
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Default Re: another nitrous question

Originally Posted by jwhitehead
wow, i never expected so many responses, Thanks for your help. Everything made sense to me with the exception about pulling out the power valves, why and should the holes be plugged or left open?

Also the fuel log is a BG, it has a built in reg. with multiple feed lines, I use one with a tee to feed the carb and the other has a tee and has a reg feeding the fuel solenoids. And of course the nitrous is fed from the bottle to the nitrous solenoids.
I can adjust the pressure at the log regulators or at the fuel pump. I can turn the pump on and the pressure is @ 10 psi , it doesnt deadhead because it has a return, I did block the return and the guages pegged out.

Now, based on your info, sounds like:


pull power valves and increase jet size
Yes use power valve plugs, jet up 4 sizes to start.

bottle pressure too low
Yes get pressure up to 1000psi and purge down to 950 psi

timing retard not working
Check it

plugs too hot
Not neccesarily, AR3933 should be fine

plug gap too large
26-35 should be fine

maybe change nitrous jets to 28/32??????? help
Deffinatley, and flow the fuel to 6lbs of flowing fuel pressure. If you dont have a flow tool, buy one or build one, never trust an inline gauge.


Did I miss anything?
Be sure to bring extra underwear :lol:
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Old 10-09-2008, 02:16 PM
  #20  
jwhitehead
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Default another nitrous question

Thanks, everybody, looks like we got enough information to make this thing run. Will let you know how it does.
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