nfld85GS

iTrader: (2)

So i got my wideband installed and done some intial tuning of the carb, but i noticed that everytime i hit the gas, the carb goes lean. right now there are 50s in there, but when looking online i only saw two sizes larger (55 and 60). would these be large enough to prevent bogging when i hit the gas.

also when crusing, it runs rich (around 10.5 10 11.5). i'm guessing that smaller idle jets are in order, so i ordered 60s and 50s to replace the 70s. would the idle jet cause that amount of richness when barely hitting the gas? when i push a little harder it goes up to 14.5. I know that i have way to small main jets in, but this is the only way i can keep the air fuel ratio around 14.

so in the end, will the 60 pump jet help out with the bogging when hitting the gas hard? and does the idle jet cause the richness when crusing?

thanks!

sgieldon

What Fuel Pump are you using?
Sounds like your running out of Gas.
Stock Pump will not keep up with your setup.
Give us more info so we can start somewhere????
sgieldon
steve

nfld85GS

iTrader: (2)

i have a carter fuel pump with a holley 1-4 psi regulator set at 3.5. i have ordered a 3.3 needle seat from mazdatrix to replace the 2.0 in the carb right now. anything else you need to know, i can answer for you. thanks!

13BMiata

Man, I've been fighting this battle with my car and just (I think) solved the problem this past weekend by installing new pump jets (60's). Also make sure the jet in the bottom of the float bowl is the '0' type, as in zero back flow to the bowl when the accelerator pump is in use. I took mine out and blew thru it. It needs to be completely closed if you blow thru it backward.

No A/F meter tho, so I took a stab at the pump jets and ordered the 60's from aircooled.net.......also ordred 42mm chokes. Didn't need the chokes. My stumble was just a cough when tinkering with the car sitting still, but on course it was a major 'fall on it's face' kind of stumble. With the 60's, the accel pump stumble is GONE entirely just having changed out the jets, and it sounds great. Haven't driven it yet. Will do next weekend at SCCA event.

FYI, I was dealing with the RB 51 IDA in it's original config, on a decently sized bridgeport.

REVHED

What size venturis are you running? With big venturis there will always be a bog when opening the throttle. I used to run 42's with a 48IDA on a 12A streetport. The damn thing didn't get going till 4500rpm but it screamed in the top end.

nfld85GS

iTrader: (2)

thanks for the info 13Bmiata. I will have to order those pump jets as well. I will also have to check the jet at the bottom of the bowl. I believe that it is a 0 but not for sure since i didnt' even know it was a jet!!

REVHED, i am currently running 37mm venturis but i have 40s sitting at home waiting to go in at some point in time. I'm just hoping that i can eliminate the intial bog and lean up the crusing A/F ratio. thanks!!

680RWHP12A

i was thinking the bypass jet isnt a zero, because with 37mm venturis, a 50 squirter should be pleanty

Jaime Enriquez

3.5 psi fuel pressure! Webers need at least 4-5psi. I run mine at 5psi all day long with the stock needle and seat.