how come when i use nitrous it works great in first gear then gets worse in each gear after that and seems to sputter. i have msd ignition, filed down plugs so it should work great. i'm wondering if my 2.73 gears have anything to do with it?

87 firebird,305 4bl,sniper system,700r4

 

what is your fuel pressure at? what do the plugs look like right after you make a pass?

 

i dont know what the fuel pressure is at, i have a 110 gph holley fuel pump.

 

if it gets worse after each gear sounds like the fuel pump isn't keeping up. I'd hook up a fuel pressure guage to see what is going on.

 

filed down plugs?

 

yeah, i read in hot rod magazine to file down the ground strap and round it off. That keeps it from getting to hot and causing pre-ignition, or you can go with race plugs that already have shortened ground straps.

 

what do the plugs look like? what does the fuel pressure look like? dependign on the type of sputtering youre tlaking about.. it could be way fat and loading up after first gear and just getting worse. or the pump could be dying off and its getting leaner and leaner.

 

i ran it with nitrous yesterday and then pulled some plugs. It does look like a lean condition, the plugs were sort of whitish.
I was told by a summit tech person that he thinks it is a lack of fuel and pressure. They said to go with a holley 130 gph pump and a regulator set at 6.5 psi and that should solve the problem. I sure will be happy if it does.

 

if your having a problem with nitrous and the car feels like it is "nosing over" you should let out of it not continue through the gears. The plugs should look like new when removed, but to be on the save side run a little fat. are you running a dedicated system for the nitrous or one pum for the motor and bottle? i currently run a seperate cell with race gas with a holley blue and holley reg. seems to work fine i also pull timing out with a digital 6 box. good luck fixing the problem also if you do decide to test again post a pic of the plugs immediately after do not idle around on them or anything after.

 

I am running one pump for the motor and bottle. I talked to a summit tech person and they said to step up to a holley 130 gph with a regulator at 6.5 to 7 psi and it should work properly. also do i put the regulator in between the fuel pump outlet and the carb?

 

I would reccommend running a second fuel line with it's own pump just for the nitrous system or a fuel cell with it's own pump. I'm not sure what shot your running but if you read the NOS instructions it states that they recommend running a dedicated fuel system just for the nitrous.

You have to remember that your fuel pump is rated at free flow. A 110 gph fuel pump may only run at half that under operating conditions.

I run a 2 quart fuel cell that a plan on upgrading to a one gallon this summer. It's enough for a few shots down the track. I run a carter 110 6 psi fuel pump with a max psi of 8 so I don't have to regulate it. I would recommend doing something like that.

 

How big is the bottle and how do you have it mounted?

 

He should have an orange ten pound bottle. I have the same kit, but I got rid of the bottle valve due to it being a standard medical grade style valve. I replaced it with a NOS Hi-flo valve with the bigger outlet so it would work with my remote bottle valve.