hosspala

need some input on experienced users, jet calculators dont work in my opinion, i have a 383 LT4 with pro race fogger setup, i have been running 32N 28F and i am haveing a problem burning electrodes off my AR94s, the plugs read fat, im running about 5.5psi of fuel off a stand alone system, 950psi of nitrous pressure, running about 20deg of timming, this should be about a 200-250 shot depending on who you ask.

am i running my jet spread wide enough? we run 4 number spreads on our carb cars, is the fuel injection different? let me know what you guys use or have used in the past, thanks Robert

a few different jet combinations would help

LT4383

what compression? what octane?

srsnow

Normally on a Pro Race setyup you would start off at 32 squaered with between 5.75-6psi of fllowing fuel pressure. To set the fuel pressure use a 91 NOS jet. Also are you using Soft Plume nozzles or the Anulars?

hosspala

it should be about 10.5 maybee 11:1, its fat top SRP pistons, heads are stock no shaved, midly ported, i run 100 octane for motor, running 112 and have tried 116 for the dedicated fuel system for nitrous

hosspala

nossles are B nossles, anular nossles, we use 73 jet for flowing fuel at 5.5psi, thats just what weve always used on everything else

LT4383

This is only speaking form my exprience, but I had problems on a 200 hit with 100 octane and 12.1. Switched to 110 and was okay. This is on the mountain -no air up here-. I used an A1000 feeding the motor and the fuel noids for my DP, therefore my system always ran at 55psi. Those AR94's should be cold enough, but I've never had a problem running colder plugs if it's a track only car.
Also what size feed line you using? I never picked up any MPH with anything over 250 on a -4 feed line. In a perfect world -4 should feed a 400 hit; guess my worlds chit.

hosspala

-6AN nitrous bottle line to Y at motor with about 8in of -4an going to each selinoid
-8AN fuel cell to regulator, -6AN from regulator to selinoids

LT4383

Hmmm....you've got me.
The motor itself isn't straving is it?
Might wanna try those an AR93/92.

srsnow

Are they B nozzles or Anular? The Anular (R nozzle) can be tricky to plumb if it is not in the manifold right it can pull a vaccum on the fuel side. Are you using a 73 Holley jet because that is only a .079" orifice. The idea behind using a 91 nitrous jet when setting the fuel pressure is that it simulates the total area of the 8 32's so the restriction to flow is the same as when you have the fogger hooked up. This will give you an accurate fuel pressure. Flowing it with the 73 jet will actually cause the fuel pressure to be lower than the 5.5 psi you set it to. If they are B nozzles they don't usually need to be stagered much untill you start getting into the high 30' or low 40's in jet size. At that point the nozzle can start to have some restrictions that may requrie stagering.

hosspala

so your saying other than the fuel pressure, the jets should be almost squared, if not the same, like 32,32 or possible 32N,30F

i was thinking that the anular and B nossles where the same, i could be wrong, the nossle sprays out the side, not the bottem, and its located just below the injector spraying towards the head

srsnow

The B nozzle is a brass nozzle that is a 90 degree outlet, the R nozzle is a straight stainless nozzle. Yeah square jetting is where I would start it is the eaisest to tune. And it is important to use the proper test jet when setting the pressure. A lot of people use a 73 holley but unless you have done a lot of testing and know what fuel pressure you need with each diffrent jet setting then it is better to just set it the standard way, that way youknow the pressure is right.