Hey guys,
My RX-2 with a 51 IDA pulls SO much better than my 7 with the 48 DHLA I've just put on. At low revs, the 2 feels like a damn diesel truck, comparatively. I'm thinking my progression tuning is way off and I imagine I need to change the idle jets but don't know what I need. Here's what I have now.

215 Main
180 Airs
80 Idle
75 Pump

Additionally, my big, fat Dellorto book talks about turning the idle speed adjustment. Of course, there's the two idle MIXTURE screws and there's the throttle stop for the butterfiles, but I can't, for the life of me, find an idle speed adjustment. In order to tune this thing, the idle speed is the first thing to tune and I'm up against the wall. Any help?

 

The butterfly adjustment is your idle speed aduster, If you can't get the revs down low enough that means your mixture screws are to far out of adjustment.

 

Can someone give me a good breakdown of the jets they're running? My progression blows - very rich and burbles at low throttle. I know i've got to change jets, but really don't know where to start.

 

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

 

Of course, but I'm looking for what other guys are running on 3-port 13Bs. I'm running the setup from gruntled.com and it's just not running right.

 

I meant 4-port.... Damn. I'm a retard.

 

um... i donno... i have 48 dhla on my se n its soo much faster. runs n idles nice too. it eats alot of gas though... is ur fuel pump feeding enough fuel?

 

Not at high revs, no, and I know I need to fix that, but the progression sucks too, and that's just jetting. What idle jets are you guys running?

 

BTW, my Dellorto also whistles at idle, sounding like a little "cheep, cheep" like a little chicklet. Do they all do that? It sounds like a belt or something, but it's not.

 

bump

 

check for vacuum leaks. that was one of my main prob in the begginin. easy way to find one is to spay some carb cleaner around the carb n manifold while the car is running. make sure u dont spray it on the air filter. if the rpm rises, then that means theres a leak somewhere. keep sprayin untill u can find where. at high revs, thats where the sound might be commin from.

 

do a search for " dellorto woes "

 

i need to know more about your motor, porting, and exhaust to give a detailed jetting reccomendation. but in a nutshell:

240 main fuel
230 main air
80 idle fuel jet (this controls progression fuel deliver)

you have to make sure you have a good aftermarket fuel pump. stock one cannot supply fuel under hard throttle. I use the Holley 110gph pump, it comes with a regulator. Others like the Carter fuel pump. I set fuel pressure to 2.25 or 2.50psi, others like more (4) but I have not seen a need for such high fuel pressure.

After all that, if it still lacks power at high rpms, give it a tuneup, change fuel filters (including the one in the carb fuel inlet). Still down on power, use 220 main air. If the progression is still coughing bump up to 82 - 85 idle fuel jet.

I can rebuild your dellorto but it'll take a few weeks... I'm backed up with projects right now.

As for the whistle, that is a vacuum leak of one sort or another. I would bet that the choke is on. Make sure it is snapped shut and that the little black plastic lid on top of carb has a good tight seal.

 

I've rebuilt the carb before installing it and, other than setting the floats, there's nothing at all to it. I'll check the choke tower, but how can you ever be sure it's sealed other than taking the cover off the carb and sucking on the bottom of the tower (cough, cough)? My upper-lower manifold junction is a little loose because the air filter hits the rotor housings, so I'll tighten them down and go looking.

If the manifold and choke are tight, where else might the dellorto leak?

Oh, and thanks for the jetting.

 

Oh, and the engine's a streetported 4-port 13B w/ RB streetport exhaust (relatively short primaries).

 

mine was leaking from one of the vacuum plugs...

 

I've checked all my gaskets and stuff. Where are the vacuum plugs? Do you mean the blank phillips-headed pieces that just block off the casting holes?