Specs: 1985 roller 302 block stock crank forged pistons and rods bored .30 over (306) Pete Jackson gear drive set to advanced position Edelbrock Rollin Thunder cam E7 heads with springs for the cam with ARP head bolts Weiland dual plane intake Holley Street Avenger 670 NOS cheater wet nitrous kit (set to 125 shot currently) Ford HEI distributor (18 initial 38 total) runs on 91 pump gas hi all, so my question basically is what should i do to my current setup to accept nitrous better. i know i should have an MSD or similar ignition kit with the box but there are a lot of chevy guys running a 150 shot with there stock hei with no problems. so do i NEED an ignition system like MSD or will it just optimize my shot? also if anything what else should i change or think about changing? i know i need a colder plug so could someone show me a plug that would be like 2 colder? and i know i need to retard the ignition timing, but how much? any tips would be greatly appreciated as well this is my first nitrous setup (and first engine build) so i am kind of new to nitrous. the last thing i want to do it ruin this motor by not knowing enough about what I'm throwing in my engine. thanks to all in advance!
An MSD box with timing retard would be a good idea. Better spark will help the combustion and you can wire it so that it retards the timing when the nitrous is activated. Another benefit of an MSD is a Rev limiter which is also important especially when using nitrous. Better to spend the money up front than blow things up later. Hopefully you have a free flowing exhaust system too. I forgot to add higher octane fuel...
Mallory also makes an ignition box called a "Nitrous 6" that will pull timing out of the engine when the spray is activated. It has an adjustable rev limiter also. I would also recommend some MLS head gaskets and a high flow electric fuel pump to back up your mechanical pump, if you are running one.
okay so before i use the spray an ignition system with a box would be a very good idea correct? and an electric fuel pump sounds like a good idea. right now I'm running an edelbrock mechanical pump.
my edelbrock mech. pump is claiming 110gph.... isn't it 50 gph per 50 shot correct? so to bump up to 150 shot i want at least 150 gph, preferably more right?
The company you got your nitrous kit from would also be a very good source for information and recommendations.
I agree. The better nitrous system companies are very specific regarding fuel system requirements. My personal preference is Holley's HP series of external pumps, if for no other reason is that they are quiet. If you have ever heard a loud, buzzing pump on a street driven car, you will appreciate this. The electric pump will act as a boost pump to ensure your mechanical pump has an ample supply of fuel at the inlet under all driving conditions. I think the ignition retard feature of the ignition box is a must have. I'm going to use a "Nitrous 6" box next year with my Zex system.
yeah i really like how that nitrous 6 box works from the reading I've done... and that pump sounds like a good idea too.... and ill contact the manufacturer and see what they say.
If you are interested you should do some research on progressive nitrous controllers and window switched. That should keep you busy!
I highly recommend window switches. I have had great sucess with them, being able to controll what rpm and gear nitrous is activated in is a great safety feature. You can also look around for a fuel pressure switch to shut off the nitrous in the event you lose fuel pressure. I ran all of those with a msd pulling 2 degree's timing for every 50hp shot. Ran a 200 shot on my 358 sbc Nova for years and never once had an issue other then traction
I never did mess with a progressive controller. For a street car the window switch was plenty of tech for me. With the 200 shot I had to tune the nitrous almost completely out of 1st gear.....course the 4.11s and th350 didn't do me any favors.
ive ran all kinds of different nitrous systems and control gadgets. the hei distributor is strong enough for nitrous a timing retard is helpful. the rule of 2 degrees for every 50hp is good, or you can go up in octane and not need to pull as much timing. its better to start out over safe and do both. fuel pressure switches dont work. when the nitrous hits their will be momentary drop in fuel pressure that will trigger the fuel pressure switch and the system will shut off then pressure will come back and the system will turn back on then off ect.. if you adjust the switch down to the point where it wont turn off the pressure will be too low before the switch shuts off and go too lean. a return style fuel system will prevent this but its not worth the cost just to be able to use the fuel pressure safety switch. get a fuel pressure gauge instead and keep an eye on it. fuel pressure gauge and nitrous pressure gauges are very helpfull. a bottle heater is very helpful. you will want to keep your bottle pressure above 950 psi. a bottle blanket is helpful if you are in a cool or cold environment with keeping the bottle warm and at temp. the window switch is very helpful. having the nitrous turn off if a shift is missed or something brakes and keeps the motor from over reving. progressive controllers work by pulsing the solenoids. this pulsing is felt like a surging and is very annoying and not very effective. a waste of money. i find that i can tune the harshness of the inital hit by changing the length of the fuel and nitrous lines from the solenoids to the plate. to have it hit harder you make the lines the same length or the nitrous line a little bit shorter than the fuel line. this usually is not necessary. to soften the hit start making the nitrous line longer than the fuel line. this will soften the hit. what is happening is the nitrous is being injected at 950 psi and the fuel is at 5 psi. that nitrous gets in the motor alot faster than the fuel will so you get a moment of leanness that can cause a lean back fire. ideally you want both fuel an nitrous to hit at the same time. i usually start with one inch longer nitrous line. then you change that for what ever your traction desires.
