Post SU Carb Re-Build Revelations and Such

[Dadandson]

Finished rebuilding my SU carbs, AUD 549, myself and I am amazed at the difference. Took a long drive up to Wickenburg this weekend and after checking my mileage found it went from 25 MPG to 30.1! The car responds and runs great. I want to try to increase its performance so I downloaded and registered the WinSU software to try different needles. I currently have ABC's in the car and the software recommended ADJ's. Spoke to Joe Curto and he does not have ADJ's. Is there a needle or needles that someone recommends? My 1275 is stock except it has a pacesetter header, oversize tires and velocity stacks with cone shaped K&N air filters.

 

[jlaird]

What does Joe recommend in place of ADJ's. Get some and try, they cheep.

 

[Dadandson]

He didn't recommend different needles. He suggested changing the weight of my motor oil and to try pulling out the choke a little to see if it made any difference.

 

[jlaird]

Well Joe is a respected expert. I would do as he suggests.

 

[JerryB]

D&S

"""" I want to try to increase its performance"""""

It all depends on what air /fuel ratio you have now with your now needles in the various stages (numbers) as the needle raises out of the jet. is it correct? Will richening or leaning in the midrange or full throttle be what the motor wants to see??

You can spend a lot of time and $$ on needles UNLESS you use an O2 sensor and gage or an air/fuel ratio meter and the motor is under load. Best case is a chassis dyno.

You have the later model non fixed needles. By changing the needles to a larger number in a given station you will lean the motor at that station setting in the jet. Smaller station number for fatter (richer) mixture at that station.

The ABC needles are what came in those carbs from the factory. You can make a WAG and go a bit fatter in the midrange and full throttle with needles that are maybe 5% thinner in size in the mid and mebbe 8% fatter at full throttle but thats just a guess predicated on the header and better flowing air filters....compare the station numbers in that winSU program or the SU green book. Have fun.