dcoe jet sizes (read thi its really cool)
01-28-08, 10:33 AM
#76
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I was suggesting pulling them out only to see what sizes you have. If you put them back in it won't change anything, unless the jets are really dirty and you clean them up then you may see a difference. Once you determine what sizes you have that will be a good starting point to see if you need to change anything. I can't comment on the IDA as I have a DCOE. Try searching for posts containing IDA jet size and that should help you out.
01-28-08, 12:45 PM
#77
I was suggesting pulling them out only to see what sizes you have. If you put them back in it won't change anything, unless the jets are really dirty and you clean them up then you may see a difference. Once you determine what sizes you have that will be a good starting point to see if you need to change anything. I can't comment on the IDA as I have a DCOE. Try searching for posts containing IDA jet size and that should help you out.
http://www.mazspeed.com/carburetorfacts.htm
Mark
Last edited by mpk490p; 01-28-08 at 01:00 PM.
02-01-08, 11:00 AM
#78
ok just pulled the jets out not done the chokes as i have a bad back at the mo
so i have a 13b 4 port engine (12a plates and 13b rotors) the engine is street ported and made 150BHP at the fly, im considering going 48IDA as i thing the carb was set up for a 12a, if defentatly has more go and seems to bog down then take off. when it was dyno'd they did say it needed more air flow and made more BHP with no air filter (not sure if larger jets would help with this?
anyway jets currently are
60F9 idle jet
165 air corrector
F11 emulision tube
180 main
and advice would be greatly recived!
thanks
Mark
so i have a 13b 4 port engine (12a plates and 13b rotors) the engine is street ported and made 150BHP at the fly, im considering going 48IDA as i thing the carb was set up for a 12a, if defentatly has more go and seems to bog down then take off. when it was dyno'd they did say it needed more air flow and made more BHP with no air filter (not sure if larger jets would help with this?
anyway jets currently are
60F9 idle jet
165 air corrector
F11 emulision tube
180 main
and advice would be greatly recived!
thanks
Mark
02-01-08, 11:35 AM
#79
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Choke size is def important, esp since your motor is ported. So you need to know their size when you can get around to it. If you've got 36mms in there you can't flow enough air at upper rpms. You can take the choke tubes out completely and just make it a true 45mm to flow max air into that carb. Even with the 48 IDA you're not going to get more than 48, with the chokes removed from it. The bog is common if you are flooring it with an improper setup on jets. When you floor it, you're opening up 2 gaping holes and there is not sufficient RPMs to pull the amount of air and fuel in that you are allowing it to. If you eased on the throttle until the rpms got up some then you wouldn't see that bog.
Not sure what elevation you're at but that as well as air temp will affect what jets you need. The colder the air, the more dense it is so you need to adjust the amount of fuel accordingly for a proper mix. If you don't know what the fuel pressure is on your setup then you'll need to know that as well.
I think the more common size on the emulsion tubes on this setup is F7, that's what I have. I bought a lot of different idles, mains, airs, and chokes to play around with. With the smaller chokes like 36 you get more low end power but you will peter out and struggle to hit 7k rpm. So if you want high end power then you need to let her breath and use larger chokes or none at all. I found one good combo with the 40mm chokes and that was with using 205 airs and 170 mains, 65f9 idles. I have a wideband and gauge hooked up permanently so I watched it the whole time and had great results. Air temp was about 55 deg F.
BTW before I had a good tune on the carb I made 118hp at the wheels, which translates to about 140 at the flywheel. Now that I'm tuned I have yet to dyno again but think that I should be making about 125 at the wheels or 150 at the fw. With a streetport you can make closer to 200. What kind of exhaust do you have, that makes a difference!
Not sure what elevation you're at but that as well as air temp will affect what jets you need. The colder the air, the more dense it is so you need to adjust the amount of fuel accordingly for a proper mix. If you don't know what the fuel pressure is on your setup then you'll need to know that as well.
I think the more common size on the emulsion tubes on this setup is F7, that's what I have. I bought a lot of different idles, mains, airs, and chokes to play around with. With the smaller chokes like 36 you get more low end power but you will peter out and struggle to hit 7k rpm. So if you want high end power then you need to let her breath and use larger chokes or none at all. I found one good combo with the 40mm chokes and that was with using 205 airs and 170 mains, 65f9 idles. I have a wideband and gauge hooked up permanently so I watched it the whole time and had great results. Air temp was about 55 deg F.
BTW before I had a good tune on the carb I made 118hp at the wheels, which translates to about 140 at the flywheel. Now that I'm tuned I have yet to dyno again but think that I should be making about 125 at the wheels or 150 at the fw. With a streetport you can make closer to 200. What kind of exhaust do you have, that makes a difference!
Last edited by djjjr42; 02-01-08 at 11:41 AM.
02-01-08, 12:29 PM
#80
Choke size is def important, esp since your motor is ported. So you need to know their size when you can get around to it. If you've got 36mms in there you can't flow enough air at upper rpms. You can take the choke tubes out completely and just make it a true 45mm to flow max air into that carb. Even with the 48 IDA you're not going to get more than 48, with the chokes removed from it. The bog is common if you are flooring it with an improper setup on jets. When you floor it, you're opening up 2 gaping holes and there is not sufficient RPMs to pull the amount of air and fuel in that you are allowing it to. If you eased on the throttle until the rpms got up some then you wouldn't see that bog.
Not sure what elevation you're at but that as well as air temp will affect what jets you need. The colder the air, the more dense it is so you need to adjust the amount of fuel accordingly for a proper mix. If you don't know what the fuel pressure is on your setup then you'll need to know that as well.
I think the more common size on the emulsion tubes on this setup is F7, that's what I have. I bought a lot of different idles, mains, airs, and chokes to play around with. With the smaller chokes like 36 you get more low end power but you will peter out and struggle to hit 7k rpm. So if you want high end power then you need to let her breath and use larger chokes or none at all. I found one good combo with the 40mm chokes and that was with using 205 airs and 170 mains, 65f9 idles. I have a wideband and gauge hooked up permanently so I watched it the whole time and had great results. Air temp was about 55 deg F.
BTW before I had a good tune on the carb I made 118hp at the wheels, which translates to about 140 at the flywheel. Now that I'm tuned I have yet to dyno again but think that I should be making about 125 at the wheels or 150 at the fw. With a streetport you can make closer to 200. What kind of exhaust do you have, that makes a difference!
Not sure what elevation you're at but that as well as air temp will affect what jets you need. The colder the air, the more dense it is so you need to adjust the amount of fuel accordingly for a proper mix. If you don't know what the fuel pressure is on your setup then you'll need to know that as well.
I think the more common size on the emulsion tubes on this setup is F7, that's what I have. I bought a lot of different idles, mains, airs, and chokes to play around with. With the smaller chokes like 36 you get more low end power but you will peter out and struggle to hit 7k rpm. So if you want high end power then you need to let her breath and use larger chokes or none at all. I found one good combo with the 40mm chokes and that was with using 205 airs and 170 mains, 65f9 idles. I have a wideband and gauge hooked up permanently so I watched it the whole time and had great results. Air temp was about 55 deg F.
BTW before I had a good tune on the carb I made 118hp at the wheels, which translates to about 140 at the flywheel. Now that I'm tuned I have yet to dyno again but think that I should be making about 125 at the wheels or 150 at the fw. With a streetport you can make closer to 200. What kind of exhaust do you have, that makes a difference!
im used to the bogging down and i know that is kinda the way carbs are, im in the UK no idea of air pressure here though!!
if you follow the link in my sig it shows my whole build up
going to get a quote to fit a lambard sesnor so i can monitor air / fuel mix
thanks
Mark
02-01-08, 12:35 PM
#81
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Cool I'm not a member there so I can't see the pics, I'll do that later. I run my fuel pressure at about 3.5psi. From what you're saying I infer that you're not using an inline gauge for fuel pressure? How about a regulator? Stock fuel pump? I use a Carter fuel pump, Holley regulator, and inline gauge.
I wasn't implying that you need to know the air pressure there, just that elevation and air temp do influence settings. Also keep in mind that every car is different, and have somewhat different setups so what works for one may not for another.
I scored my wideband off of ebay and then had the bung welded in for like $30 and wired it all up with a buddy one day.
I wasn't implying that you need to know the air pressure there, just that elevation and air temp do influence settings. Also keep in mind that every car is different, and have somewhat different setups so what works for one may not for another.
I scored my wideband off of ebay and then had the bung welded in for like $30 and wired it all up with a buddy one day.
Last edited by djjjr42; 02-01-08 at 12:43 PM.
02-01-08, 01:07 PM
#82
that cool i apriciate that each set up is different i just think the carb was set up for possibly a stock 12a (brought it a long time ago while the car was being built and didn't know much about carbs then but im learning!)
didn't realize you have to register to see the pics!
i have a faccet red top, regulator and pressure gauge (its snowing outside and the garage is too far!!) 3.5psi sound famliur though
i have gathered having a fuel / air gauge will really help me set it up, so do you just rev the engine upto 7k and check the gauge to see which way it needs adjusting or does it need to be driven?
as long as you dont run to rick or lean at any point that the right set up?
sorry for all the questions but like i say im learning!
Thanks
Mark
didn't realize you have to register to see the pics!
i have a faccet red top, regulator and pressure gauge (its snowing outside and the garage is too far!!) 3.5psi sound famliur though
i have gathered having a fuel / air gauge will really help me set it up, so do you just rev the engine upto 7k and check the gauge to see which way it needs adjusting or does it need to be driven?
as long as you dont run to rick or lean at any point that the right set up?
sorry for all the questions but like i say im learning!
Thanks
Mark
02-01-08, 02:46 PM
#83
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Yes if you bought it together with the manifold then it probably was. That doesn't mean you can't get it to run on yours though, you just may have to change things up a bit. Revving the engine won't help, it has to be under load, i.e. driving down the road or on a dyno. You also can't just wind it out in first gear, that won't work either. You need to try to get on open road where you can push it up in 3rd and get into 4th pretty good. If you could get close to redline in 4th that would be best (if you ever "drive" that fast) but you'll probably be breaking some laws, LOL. You're ok running too rich, you may foul up plugs sooner and whatnot and you're not making the most possible power. Running lean however, expecially at WOT can lead to catastrophic engine failure. Stoich is 14.7 but you should aim for about 13.5 at WOT which is a little bit rich but your rotary will like it there. You never want the guage to read over 14.7 while accelerating. It's ok to see it above it when you have backed off the throttle and are coasting.
Don't worry about the ?'s, that's what the forum is for. Good luck with it m8 and let me know if I can help you out any more.
Don't worry about the ?'s, that's what the forum is for. Good luck with it m8 and let me know if I can help you out any more.
02-01-08, 03:43 PM
#84
Yes if you bought it together with the manifold then it probably was. That doesn't mean you can't get it to run on yours though, you just may have to change things up a bit. Revving the engine won't help, it has to be under load, i.e. driving down the road or on a dyno. You also can't just wind it out in first gear, that won't work either. You need to try to get on open road where you can push it up in 3rd and get into 4th pretty good. If you could get close to redline in 4th that would be best (if you ever "drive" that fast) but you'll probably be breaking some laws, LOL. You're ok running too rich, you may foul up plugs sooner and whatnot and you're not making the most possible power. Running lean however, expecially at WOT can lead to catastrophic engine failure. Stoich is 14.7 but you should aim for about 13.5 at WOT which is a little bit rich but your rotary will like it there. You never want the guage to read over 14.7 while accelerating. It's ok to see it above it when you have backed off the throttle and are coasting.
Don't worry about the ?'s, that's what the forum is for. Good luck with it m8 and let me know if I can help you out any more.
Don't worry about the ?'s, that's what the forum is for. Good luck with it m8 and let me know if I can help you out any more.
will post the other details up tomorrow when i get them
thanks again
Mark
02-01-08, 05:32 PM
#85
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Ok but I will be gone for the weekend so I won't be able to post again until Monday. Odds are you are going to need to purchase some jets anyway to play around with, its not an exact science and different settings will give you different characteristics and shift the power band around. Good news is that they are pretty cheap. Its all about personal choice in how you want the car to perform.
Btw I've found that a few beers helps alleviate any pains while working on the car!
Btw I've found that a few beers helps alleviate any pains while working on the car!
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