View Full Version : 2.3mm needle jet
Hi All
anyone started mass producing these that close properly yet?
thank you
car.crash
14-03-2010, 19:55
what power are you running to need bigger than a 2mm? iirc logg bought a 2.3mm off the shelf that fitted but the float was not strong enough to close it.
23 psi on the cards. float empties high up the rev range!
its either that or drop a fuel solenoid into the main jet screw and switch the fuel on manually urg!!!!! oo or try hooking it up to a float sensor of some sort to switch off as the chamber fills!
ahh balls efi!
2mm is fine for 23psi...well, I say that, 1.7mm worked alright for me :D
2mm is fine for 23psi...well, I say that, 1.7mm worked alright for me :D
did you check your lm1/lc1 read outs in 3rd at 6k+ on a 1.7mm?
car will run 23psi easy on a 2mm that i have, but not sure how long the car will run on prolonged bost with the chamber emptying :D
Yep, you'll struggle to keep the jet closed at 2.3mm size. Either reduce the fuel pressure (not wise) or source a larger float, but then that reduces the fuel capacity of the float chamber, so it's a double whammy.
Best bet would be to retain the 1.7mm needle valve, 'T' some fuel off from the carb supply line, remove the main jet blanking plug & fit a relevant size nozzle instead, with a crack valve/solenoid(*) inline that opens at, say, 18psi boost, and feed the float chamber with the additional fuel that way.
* You could even use the o.e overboost sensor as the ref' point trigger.
Ok, I was too slow typing. You've already thought of that! :D
did you check your lm1/lc1 read outs in 3rd at 6k+ on a 1.7mm?
car will run 23psi easy on a 2mm that i have, but not sure how long the car will run on prolonged bost with the chamber emptying :D
I did indeed, 20lbs, 12.3 afrs at wot in 4th/5th @ 6500...little rich for some people but no issues with my engine...I couldve nudged the boost a couple of psi more but I think that wouldve been on the cusp of goin crazy lean at those revs with that boost :)
Like I said, worked well for moi :D
car.crash
14-03-2010, 20:57
I did indeed, 20lbs, 12.3 afrs at wot in 4th/5th @ 6500...little rich for some people but no issues with my engine...I couldve nudged the boost a couple of psi more but I think that wouldve been on the cusp of goin crazy lean at those revs with that boost :)
Like I said, worked well for moi :D
i had similar results at 20 psi with a 2mm needle, 1.3 second stage and 1.3 main.
turbo ted was running 25 psi maybe more on a 2mm needle down the strip.
I did indeed, 20lbs, 12.3 afrs at wot in 4th/5th @ 6500...little rich for some people but no issues with my engine...I couldve nudged the boost a couple of psi more but I think that wouldve been on the cusp of goin crazy lean at those revs with that boost :)
Like I said, worked well for moi :D
Werent it on std cam though mate? With a hot cam in the 2mm+ jet is necessary for higher boost!
On my current setup the 2mm needle runs out of puff at 18psi, i need to sort it.
car.crash
14-03-2010, 21:11
Werent it on std cam though mate? With a hot cam in the 2mm+ jet is necessary for higher boost!
On my current setup the 2mm needle runs out of puff at 18psi, i need to sort it.
what solutions do we have other than efi or what mart said?
An injector running off something like ERL's MF2 unit.
An injector running off something like ERL's MF2 unit.
Blimey thats old hat, DD did that about 8 years ago :devil:b;)
Blimey thats old hat, DD did that about 8 years ago :devil:b;)
Aii, and I had tried it a couple of years prior to that :D ;)
Yep, you'll struggle to keep the jet closed at 2.3mm size. Either reduce the fuel pressure (not wise) or source a larger float, but then that reduces the fuel capacity of the float chamber, so it's a double whammy.
Best bet would be to retain the 1.7mm needle valve, 'T' some fuel off from the carb supply line, remove the main jet blanking plug & fit a relevant size nozzle instead, with a crack valve/solenoid(*) inline that opens at, say, 18psi boost, and feed the float chamber with the additional fuel that way.
* You could even use the o.e overboost sensor as the ref' point trigger.
thats probably the best option.
im running a T28 and a piper 285...a 1.7mm on its own is no good. the 2mm holds its own into the 20/21psi region.
T'ing off a second fuel line into the main jet plug maybe the way to rock and roll.
its just getting the solenoid to close when the float fills.
rs250nut
14-03-2010, 21:38
I had something similar on my old set up that was installed by e.p motorsport. Bit crude to be honest valver cold start valve stuck in the back of the inlet manifold with part of it protruding in to the main inlet tract:crap: It worked off an adjustable boost switch and using a phase one fuel pump off the reserve tank. Better ways to add fuel if you need too.
thats probably the best option.
im running a T28 and a piper 285...a 1.7mm on its own is no good. the 2mm holds its own into the 20/21psi region.
T'ing off a second fuel line into the main jet plug maybe the way to rock and roll.
its just getting the solenoid to close when the float fills.
You wouldn't have to. Just use a restrictor (something like a main jet would do) in the solenoid feed line to limit how much fuel goes into the float chamber. Go on the basis that a (for example) 0.5mm jet/restrictor + the o.e 1.7mm needle valve would effectively be like having a 2.2mm needle jet in situ. Edit: ish.
If you find you aren't getting enough fuel still, drill out the restrictor/jet thus so.
If you find the carb/engine is flooding, reduce the restrictor/jet size.
Werent it on std cam though mate? With a hot cam in the 2mm+ jet is necessary for higher boost!
On my current setup the 2mm needle runs out of puff at 18psi, i need to sort it.
Yea, standard cam ftw :D
Thats got to be the way forward Mart.
I have a similar setup as backup, got it off sparkie. Adjustable prv valve & banjo fitting to go in the main jet hole, with suitable restrictor.
mart, you'd need more than 0.5mm in the line to get anywhere close to the fuel a 2.3mm jet would flow. x-sectional areas and all that :)
It's wierd though, I had no probs with a 2.3mm jet in mine, it just took a couple of attempts to get it sealing right. some people can't make 2mm work. It's like some floats are better than others ? If you havn't already maka, take the pressure reference for the regulator straight from the compressor housing, it'll help get the fuel pressure up on boost.
car.crash
14-03-2010, 21:51
Thats got to be the way forward Mart.
I have a similar setup as backup, got it off sparkie. Adjustable prv valve & banjo fitting to go in the main jet hole, with suitable restrictor.
would that have been designed for the lairy cam he fitted :D
Aii Brigsy, a prv (that's what I meant by crack valve) will work just as well and takes the wiring-up side of things out of the equation, and you can still fit a restrictor inline if needs be :agree:
Win :)
mart, you'd need more than 0.5mm in the line to get anywhere close to the fuel a 2.3mm jet would flow. x-sectional areas and all that :)
Come on mate, give me some credit. It was an example...
mart, you'd need more than 0.5mm in the line to get anywhere close to the fuel a 2.3mm jet would flow. x-sectional areas and all that :)
It's wierd though, I had no probs with a 2.3mm jet in mine, it just took a couple of attempts to get it sealing right. some people can't make 2mm work. It's like some floats are better than others ? If you havn't already maka, take the pressure reference for the regulator straight from the compressor housing, it'll help get the fuel pressure up on boost.
I done a 2.3mm needle that sealed perfectly on the bench, was fine for ten mile then spat its dummy out. Im going to have another attempt before i totally give up :)
Come on mate, give me some credit. It was an example...
Sorry mart, didn't mean it to sound funny. What I ment was you'd need sommat like a standard 1.7mm needle with a 1.6mm restrictor in the new pipe to get a total flow equivilent to a single 2.3mm needle.
It's all good :agree:
Like I said, the 0.5mm value for a restrictor was just an example.
I know, but I thought it was worth discussing if people were going to get on and give this a try :)
Aii, which is why I also said about drilling/reducing the jet size accordingly if more/less additional fuelling is required :)
Ok, let's just forget the whole 0.5mm example... :rolleyes: :D
Alastair
14-03-2010, 23:40
Some useful tools and information here for calculating how much fuel youll get through different sized restrictors:
http://www.flowmeterdirectory.com/flowmeter_orifice_calc.html
and here:
http://www.simetric.co.uk/si_liquids.htm
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions Inc. All rights reserved.