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Holley jet flow chart? #1808386
04/21/15 05:14 AM
04/21/15 05:14 AM
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sshemi Offline OP
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I need to jet up 10% from going to oxygnated fuel.
It would be a guess at best without some jet flow chart.
Anyone have one or know where i can find one?
Thanks

Re: Holley jet flow chart? [Re: sshemi] #1808435
04/21/15 10:11 AM
04/21/15 10:11 AM
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"Somewhere" I saw a some a couple of jet flow charts, but I remember comparing them and the #s weren't in synch w/ each other and didn't bother to keep the info.

I don't know if it will help, but I posted THIS CHART on http://racingfuelsystems.myfunforum.org a ways back. If nothing else, you could calc areas for the jet diameters and ballpark it by looking for a 10% increase in area to start with.

Re: Holley jet flow chart? [Re: sshemi] #1808481
04/21/15 10:53 AM
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i do the math on jetting. i figure the square inches of opening on the jets and then multiply the percentage of increase or decrease i want. i never just jump up or down by numbers and i don't trust holley's "flow" charts. the newer holley brass jets aren't made as good as the old steel.

Re: Holley jet flow chart? [Re: lewtot184] #1808575
04/21/15 01:10 PM
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sshemi Offline OP
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I dont have the tools to measure the hole of them.

Re: Holley jet flow chart? [Re: sshemi] #1808614
04/21/15 02:15 PM
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Originally Posted By sshemi
I dont have the tools to measure the hole of them.

This page lists Holley jet #s and hole sizes, although I don't know exactly where they get the data: http://www.smileysracing.com/shopping/productDetails.aspx?i=98346&c=2054

Or, check the chart out that's posted on this page: http://realoldspower.prophpbb.com/topic4044.html

Beyond this, I think you're on your own. up

Last edited by BradH; 04/21/15 02:24 PM.
Re: Holley jet flow chart? [Re: sshemi] #1808668
04/21/15 03:30 PM
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Originally Posted By sshemi
I dont have the tools to measure the hole of them.
You don't need to measure them. Holley jets are based on flow, not hole size. But to get you close, use the chart posted above, see what actual drill size is of the jets you HAVE. Add 10% and see what jet you NEED based on that calculation. You will still have to tune it, but this will get you close. Figuring a 10% increase in area, will be more accurate than just a 10% increase in drill size.

Monte

Last edited by Monte_Smith; 04/21/15 03:33 PM.
Re: Holley jet flow chart? [Re: Monte_Smith] #1808765
04/21/15 05:43 PM
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BradH: "... you could calc areas for the jet diameters and ballpark it by looking for a 10% increase in area to start with."

lewtot184: "i figure the square inches of opening on the jets and then multiply the percentage of increase or decrease i want."

Monte_Smith: "see what actual drill size is of the jets you HAVE. Add 10% and see what jet you NEED based on that calculation.... Figuring a 10% increase in area, will be more accurate than just a 10% increase in drill size."

Uhhh... didn't we all pretty much just tell the OP the same thing? shruggy

Well, at least he got a consistent response. wave

Re: Holley jet flow chart? [Re: BradH] #1808923
04/21/15 09:01 PM
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sshemi Offline OP
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Thanks guys.
Just got a reply from holley where i asked about this.
They say that one jet nr bigger equals 2% in flow.
Seems kinda generic to me.

Re: Holley jet flow chart? [Re: sshemi] #1808958
04/21/15 09:34 PM
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It isn't generic, it is the way some engineer designed the system years ago. It makes more sense to have each jet size provide a change in flow rather than a size change. When you change jets you want to change flow, the size doesn't mean anything.

So if you have a good baseline and then the air density changes by 2% you change one jet size. Air density gauges provide % readout so it makes sense that the jets should be sized by flow % also.

It all makes sense once you understand it. You just need to think in terms of flow rather than drill size or pin size.

Re: Holley jet flow chart? [Re: AndyF] #1809196
04/22/15 04:07 AM
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So should i just jet up 5 nrs to get a 10% increase?

Re: Holley jet flow chart? [Re: sshemi] #1809264
04/22/15 10:27 AM
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I've got the flow chart at home from Holley. Some jets are the same hole size but have different tapers. I'll post the sizes for you tonite. Dave

Re: Holley jet flow chart? [Re: sshemi] #1809453
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What are the jet sizes right now?

Re: Holley jet flow chart? [Re: sshemi] #1809608
04/22/15 05:53 PM
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Maybe, hard to tell unless you have a chart with flow numbers.

I use BLP jets and they show actual flow on their charts. Then you can quickly figure out which jet to use if you need to change flow by a certain percentage.

I do know one guy who has a flow bench for jets. He flows all of his jets and stores them in little compartments sorted by flow #. So he can read an air density gauge and then get the tune up correct the first time. I'm sure the big boys in the Pro classes do the same thing.

Re: Holley jet flow chart? [Re: AndyF] #1809935
04/23/15 03:56 AM
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92s from the beginning.
Put in 97s pri and 98s sec.
Seems to work ok but i only got to test drive a couple of runs then the transmission gave up:-(

Re: Holley jet flow chart? [Re: sshemi] #1809968
04/23/15 07:19 AM
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10% richer than 92's would be 94's. 97's are +25% and 98's are +30% according to Holleys flow sheet.Dave

Re: Holley jet flow chart? [Re: quickd100] #1810085
04/23/15 12:43 PM
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sshemi Offline OP
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That doesnt make sence???
Guy at holley said every nr up is 2% increase???

Re: Holley jet flow chart? [Re: sshemi] #1810089
04/23/15 12:48 PM
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Originally Posted By sshemi
92s from the beginning.
Put in 97s pri and 98s sec.
Seems to work ok but i only got to test drive a couple of runs then the transmission gave up:-(


What are your idle and Hi speed bleeds.


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: Holley jet flow chart? [Re: sshemi] #1810192
04/23/15 03:02 PM
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Originally Posted By sshemi
That doesnt make sence???
Guy at holley said every nr up is 2% increase???


The average mean flow of a #92 is 1150.0 cc;s per minute. The average men flow of a # 94 is 1260.0, #97 is 1440.0 and #98 is 1500.0. That's straight off the Holley Sheet.Dave

Re: Holley jet flow chart? [Re: quickd100] #1810729
04/24/15 04:23 AM
04/24/15 04:23 AM
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sshemi Offline OP
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Thumperdart i dont have any idle bleeds.
Idle system is not even in use.
This is some tricked out carb made by arrington. Lots of mods.
High speed i dont know. Yet.
Was supposed to go to the track on saturday but a slider in my gforce 4 speed decided to split in half:-(
I will install my a/f tool for the next time out. Just need to seal all the slip on tubes first.

Re: Holley jet flow chart? [Re: sshemi] #1810842
04/24/15 12:13 PM
04/24/15 12:13 PM
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No clue there then and this is new to me so time to observe and learn.


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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