Has anyone here done some dyno tuning to get a good jet setup on the setup in the title? I have played around with my idle jets and accelerator pump jets along with my trusty butt dyno to perfect my low range (below about 4K RPM). Above 4K the car seems to fall flat on its face (the 5th and 6th ports are hooked up, need to double check that they are opening though). I also start to see my temperature rise rapidly after a few minutes cruising on the highway at 3700 RPM or above (suggesting a lean mixture). I need to play around with my jetting (and I need a beefier fuel pump as mine can't keep up with 6,500 and up demands without making the car sputter). So what main jets and emulsion tubes are you other Dellorto guys running? I need an idea of what kind of jets to order, my 230s feel quite lean, so instead of ordering 235s 240s 245s and 250s, if one of you guys is running some 260s, I'll buy a set of jets to play with in that range such as 250s 255s 260s 265s and 270s. I am using a complete RB exhaust starting with a RR header, no presilencer, and a power-pulse muffler.

Here is what I'm working with:

Idle jet holders:
7850.8

Idle jets:
80

Emulsion tubes (main jet holders):
7772.8

Main jets:
230

Pump jets:
90

 

I should also mention I'm aiming for max power, not fuel economy, but I'd at least like to get the mixture so that the engine doesn't start heating up like crazy past 4K RPM.

 

260 main fuel, way too big. what main air jets do you have? And, a wideband air/fuel meter goes a long way to get the right mixture.

6-Port 13B Stock (from RB) New!

I received settings from Daniel Ciarcia who got them from Racing Beat. Mazdatrix and Hayes also recommended these settings. Only the accelerator pump jet and emulsion tube are different from the 12A setup.

Jet
Size
Notes

Main Emulsion Tube
#7772.8


Main Fuel Jet
#230


Main Air Jet
#230


Idle Holder/Emulsion Tube
#7850.8


Idle Jet
#75


Accelerator Pump Jet
#80


Needle and Seat
#300



http://www.gruntled.com/Dellorto/

 

Hmm... that setup is exactly what I had in my car before I tinkered with enriching the idle circuit............... I think I changed my needle and seat(I didn't know they were different so I have no idea what my old seat or new current is) with the last rebuild though, and that might have messed up everything, would it even do that? Either way, with the RB exhaust, has the flow increased to the point where I need to make anything else richer? I know that my progression circuit DEFINITELY increased when I pulled the 75 idle jets and put in the 80s as wel as upping the accelerator pump jets from 80 to 90.

 

New 3.00 needle and seats are NLA. Largest size available is 2.25. Being smaller, that will lean out the entire fuel delivery curve. Fix that first by either reaming the 2.25 to 3.00 or put the 3.00 back in.

You're spot on with the idle jets and accelerator pump.

 

When I ordered a rebuild kit from www.dellorto.com a couple of years ago
they gave me a 3.50 needle and seat. Thats whats in mine now. I have a stock port
12a so can't really help help much with the jetting other than to recommend getting
a hold of this book http://www.amazon.com/Build-Power-De...6467186&sr=1-1.

Well worth the money and will help you understand how to tune what you have.

 

Yeah I emailed the guys at eurocarb and they told me to order the 350. So hopefully that'll work.

 

Ah, that's a good idea. That'll richen the entire fuel delivery curve so you might want to lower the floats a tad, or lower fuel pressure by .25psi to compensate. But that 3.50 is the best bet.