Jetting ?????

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eldabo · #1 Post by **eldabo** » Fri May 16, 2008 3:22 am

I have the zex plate and the cheater solenods just swaped from sniper.My question is the no2 jets supose to be larger than the fuel, and what spread sould I use .250 hp shot?The guy at the hot rod shop ordered me the jets and he says that it is no2 88 and fuel 63 . just seems kinda lean .
I have a one gallon fuel cel and run c16 race fuel in it .Thanks

david

#2 Post by **John_Heard** » Fri May 16, 2008 8:10 am

If the solenoids flow the full amount the jet can provide, yes that's quite a stagger between fuel and nitrous! How much fuel pressure was you planning on running? You'll need something around 16 psi with stagger like that most likely.

Did you ask him why he is using so much stagger in the jetting?

stroker1 · #3 Post by **stroker1** » Fri May 16, 2008 1:35 pm

I have heard of people staggering the jets and going smaller on the fuel side when running 1 regulator for carb and n2o. And running like 7.5 lbs of pressure for carb and fuel solenoid. But not that big of a spread. That sounds pretty far out......unless you are running a bunch of fuel pressure........

eldabo · #4 Post by **eldabo** » Fri May 16, 2008 3:47 pm

Yeah thats what I was thinking Im only running 7 psi fuel .I think I will bring the fuel jet up in size more like a 88 no2 and 82 fuel .Do yah think that would be more in line ?

rustbucket · #5 Post by **rustbucket** » Fri May 16, 2008 4:09 pm

all of nos brand kits have the fuel side larger than the nitrous with 6lbs of fuel pressure. If you jet it like that guy recommended, take a snow shovel and some buckets to pick up parts.
Go to holley's site and see the instructions for any of the plate kits and it will tell you the jet sizes. Not sure about the zex plate.

eldabo · #6 Post by **eldabo** » Sat May 17, 2008 1:58 am

yeah gotta look at that . but it looks fishy

eldabo · #7 Post by **eldabo** » Sun May 18, 2008 3:02 pm

This is the zex plate jet settings front page says biger fuel jet than the back of the page look it over and tell me what yah think .I have the cheeter solinods

eldabo · #8 Post by **eldabo** » Sun May 18, 2008 3:03 pm

http://s156.photobucket.com/albums/t1/e ... ure006.jpg

http://s156.photobucket.com/albums/t1/e ... ure007.jpg

#9 Post by **John_Heard** » Sun May 18, 2008 9:39 pm

All those jetting charts look very rich, which is typical jetting for companies to recommend. Typically a safe setting on shots that size is square jetting at about 5.5 psi, it'll be a bit fat, but not near as fat as what they tell you to start at.

That said I have no personal experience with that plate you're working with, and don't know what it can or will move in lbs per hr, so you may want to get some input from someone that's actually worked with one.

eldabo · #10 Post by **eldabo** » Sun May 18, 2008 10:43 pm

sqare is what im going to try thank ill let yah know how it goes

eldabo · #11 Post by **eldabo** » Thu May 22, 2008 10:52 pm

So I sould not rase the fuel pressure ? some one on a diff site says that thats like a 350 shot what do you think ? 88 On the no2 and 88 on fuel .One other guy says to flow it with a 73 jet and it will be close but Im not sure I know what hes meaning ,flow with 73 and sqare it at that size or flow with that jet and then put the 88 back in.By the way how much and how fast should my fuel flow at the 5.5 psi?

Thanks
I know thats a lot of questions but its the biggest hp shot Ive done and Im trying to get it right.

David

#12 Post by **John_Heard** » Fri May 23, 2008 7:02 am

IF you're going to use an 88 nitrous jet and a 88 fuel jet, 5.5 psi should be plenty of fuel. That should be about 5.1 Nitrous to fuel pressure which will likely be a tad fat. If you're going to measure fuel flow with that jet it should move .27 lbs per sec.

There are two schools of thought on what Jet to put in your flow tool for setting the fuel pressure, one says to always use a 73, the other says use an equivalent area jet (88 in this case). Both will work, just pick a method and stick to it when making adjustments. The deal is the regulator "should" regulate the pressure regardless of what jet you have that's why the 73 jet works.

Personally I prefer to use an equivalent jet method when flow testing (88) just in case the regulator has a flow issue it would be detectable (when doing flow testing by weight and time).

Don't forget to take timing out, at least 9 degrees till you get a chance to read the plugs and see where you're at.

eldabo · #13 Post by **eldabo** » Fri May 23, 2008 4:29 pm

Thanks .how do I mesure .27 pound per hr ?

#14 Post by **John_Heard** » Fri May 23, 2008 4:58 pm

That's not something you have to do, you asked how much so I gave you the volume.

Setting the fuel pressure flowing should suffice but if you want to flow the plate and measure fuel volume you'll need to remove it from the intake and stick it in a bucket and measure how much the weight it is over like a 10 second period. You'll need a timer to activate the system for exactly that amount of time so you have a vaild reading. That kind of flow testing will tell you what the entire system flows vs estimating it based on jet size. Again it's not something you probably need to do unless you're reaching the flow limitations of the plate and want to see if something is causing a restriction.

eldabo · #15 Post by **eldabo** » Fri May 23, 2008 6:51 pm

cool thanks

Jetting ?????

Jetting ?????

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