I'm looking for jetting reccomendations for using 38mm chokes on a weber 48 ida on a 13b mildly streetported 4port motor with headers. What I have so far:

Air Jets: 160
Main Jets: 190
Emulsion Tube: F11
Venturis: 38 mm
Needle and Seat: 300 as larger needle and seats reduce fuel foaming in float bowl. Any reason to use Grose Jet?
Discharge Valve in bottom of float bowl: 0 - closed
Idle Jet and holder: what size?
Accelerator pump jet: what size?

Now, why 38mm chokes? Because my motor uses original 11.58lb rotors which redline at 7000rpms. And I autocross and need low end torque to pull out of corners + no low end bog when opening throttle. So it makes no sense to install big 40mm+ chokes that reduce intake velocity.

Has anyone tried the EMPI velocity stacks?
http://www.cip1.ca/ProductDetails.as...13%2D43%2D6057

Does anyone make a nice airbox that's plug-n-play?

Thanks,
Brad

 

^

 

^ one more time.

And has anyone tried horizontal discharge nozzles (axial) instead of auxillary venturi?

 

i dont think ive ever seen them
who makes them? i think my 58mm gene berg has them, but im not sure...
as far as idlr jets brad i think 65 f9 would do the trick and i think the pump squirters should be 55? ill check when i get to the shop

 

don't know if you've seen this but racing beat guide is usually a good start

 

What idle jets and accelerator pump jets are other people using on their streetported rotary?

And what size IDA Idle Air Jet Holders? 100, 110, or 120?

 

i have just brought a new 48IDA on the same 13b 4 port street ported engine carb is coming set up as follows
Main venturi 37

Aux venturi 4.5

Main jet 135

E-tube F7

Air corrector 120

idle jet 70 F10

Pump 50

Needle valve 2.00

i was going to change the mains venturi 38/40
Main jet 190 / 200
E-tube F11
Air Jet 160
Needle Valve 250
do i need to change anything else?
thanks
Mark

 

ditch the inlet filter and enlarge the opening along with the funnel looking thingy where the needle and seat goes. that will ensure that you dont starve for gas. the rest, you will figure it out as it goes

 

F16 emulsion tubes leaned out the midrange. It pulls harder in midrange, uses less gas, and there's no cloud of noxious unburnt fuel floating around me when I pull up to a stoplight.

 

Wow f16's! Those are really lean tubes. I would use f7's or f8's and highest f11'
s. But I guess it depends on how you want the car to perform for yourself.

 

Wacky, elaborate on "enlarge the opening"........ please.

 

 

They're actually very close to F11, but leaner in the midrange.
https://www.rx7club.com/newreply.php...eply&p=4611685

 

Mine, but it doesn't run well right now
13b 86 street port
48ida
65f9 idle
120 jet holders
f-11 etube
unknown needle and pumpjets
170 air
200 mains
unknown chokes... they look like a custom grind.
from my understanding there is always a reason to run a grose jet, but I have noidea where to get one these days...
as a reminder etubes do not go from lean to rich... lean to rich i think it's:f-5 f-7 f-16 f-11 f-8
the same thing goes for the flute size with idle jets there is no rhyme or reson to the "f" numbering lean to rich is some random order as well. i think it's close to f5 f10 f8 f9

 

40mm chokes minumim...38's will kill the top. I wanna make some 41's.

My setup:
40mm chokes
300 needle and seat
70 idles
F-11 Tubes
215 Fuel
155 or 165 airs...can't remember.
"Wackymentioned" inlet mods

 

Does anyone know where to get a grose jet these days, and are they worth the money?

 

what kinda jetting factors would vary from dco/dcoe to ida? both 48's and engine 13b's? hope im not hyjacking.

 

there are very different jetting setups depending on what you have...there are a lot of posts about the different variations..try searching..either ida or dcoe for specific model jetting

 

A standard #300 needle and seat work fine. For some reason, I could never get the glass-ball grosse jet to stop seeping extra fuel on hills making the car stumble. I've tried the ones with the white ball and the black ball...

 

The main reason I ask is I read that grose jets never go bad, flow way better, and it gets annoying replacing needles every 9000 miles. I'd still love learn more about then and maybe get one just to play with if anyone knows where. To correct my last post I was running 185 main with 180 air correctors I was leaning out above 6500 and the car has a huge port. Today I swapped in some 220 mains and it falls on it's face above 6k with those in. so I tried moving to a 165 A/C and it only made it worse. I tell you what though it completely changed the midrange. it has so much more torque with thise jets and there is no such thing as a hesitation below 6k. I'm going to try out 200 mains with 180 A/Cs and see how that runs. I was told from the builder that my engine has a huge port in it and that the carb just needed to be tuned to get it's full potential, but I think the shitty Racing Beat e?haust is killing the engine. I might have to just bite the bullet and rent a dyno. $95 at a friends shop for as many runs and as much tuning as you can fit in an hour.

 

mazdatrix sells the grose jets. i set my ida to 4.5 psi and it did flood when going up steep hills with the grose jet. EGT in each header tube and the rear always ran significantly colder when going up steep hill. i lowered it down to 3.0 i think, and the egt's are much closer up hill. doesn't lean out on top end either.

AEM wideband was invaluable for tuning, have not had the ida on the dyno but i may try some 40mm chokes to see the difference.

 

well here's a question... Why does Mazdatrix list a different Idle jet for the IDA vs the DCOE? I've always thought they used the same jets... Another weird thing was that I bought some jets a while ago and they were supposed to be 65 F9's and they were 65's but there was no flute hole...

 

And... I took out the 220's and went down to 185 mains and 165 a/c's it runs way better and falls on it's face at 7500. better but still not as high as the engine was built to spin to. i need a dyno and a wide band.

 

IDA uses a totally different idle fuel jet than the DCOE. The main circuit jets are the same.

 

funny coz I used an IDA idle jet on a 48DCO carb in my FB. Worked fine