Hey All ~

I just wanted to ask 2 questions, but in the process of searching, I decided to try to sift some of the Dell threads of the past and put them all here for quick reference. I read until my eyes got fuzzy, so I may have missed some important ones - I don't know. If I did, and anyone finds them, please feel free post it.

I did this because I get the feeling we're a minority and we have limited resources to boot. I hope that it will help for future reference - maybe archives?

1

 

Dell’Orto Help Needed by Midwest 7’s

Dell’Orto vs. Weber by Calvinpaul

Who has a dynosheet of a Streetported 13B (4-port) by Drivefast 7

Dell’Orto Turbo? by Lemonade – (not very technical, but may be useful if you want to try a turbo setup)

Dell’Orto on a 13B 4-port by 13BToy

Dell’Orto Idle Mixture Tuning by 13BToy (very good info from Wackyracer (courtesy of www.aircooled.com) in this one)

Does anyone sell DHLA velocity stacks besides TWM? by Maguire

Dell’Orto side-draft carburetor by MakeRx7UpYours (DHLA and DCOE fit the same manifold)

Holley & Dell’Orto Questions by Crit (Accelerator Pump gasket idea by Drivefast 7)

Dell’Orto Woes by Spoolin

#300 Needle & Seat for Dell’Orto by 10,000

Fuel Injecting a 12A by Phaxtris (okay, may not be Dell-specific but gives a great alternative for 12A people)

Dell’Orto Question by Kouki 1st Gen

Dell’Orto DHLA setups by FD-less

Dell’Orto woes … Anybody? by diabolical1

 

Anyway, my two questions:

1. I think I remember reading somewhere that if I drill holes in the emulsion tubes, it will lean out the mixture. I just want someone that knows what they're doing to explain that concept if it's true. I'm not even close to Sterling or Rx7Carl in terms of carb knowledge, so please feel free to speak like you're speaking to a child.

I'm having problems with my mixture (it's way too RICH!) and I'm planning to get some larger air jets, but in the event that they don't do what I want, then I'm thinking my next step is drilling the emulsion tubes.

Here's what I've got ...

 

2. Aside from playing with the air jets, how else can I lean things out? I'm not too keen on swapping venturis, but I'd consider it.

Thanks

 

Hi!

Aprox at what rpm ,and throttle opening is it rich?

Drilling the emultion tube will help a bit,but its easier to make things worse,than to improve it by doing so.

What size venturies are you running Sir?And idle jets?

I would suggest to go down on your main jet size a tad.

Let me give you my specs for comparisson

38mm Venturies
200 main Fuel
210 Air Correction.
I`ll have to check the idle jets,cant remember anymore.

Karis

 

i bought it brand new in 1994 and i haven't really touched it, aside from playing with fuel and air jets. so as far i know this is how it left Racing Beat.

Venturi/Choke = #39
Idle Holder/Emulsion Tube = #7850.8
Idle Jet = #75
Accelerator Pump Jet = #80
Needle and Seat = #300

(by the way, this info was pirated from www.gruntled.com )

it originally came with 230 (fuel) and 230 (air), but i played around with fuel jets all the way down to 215. well, i can feel a difference between 215 and 220, so i settled on 220.

i'm planning to see if i can get some larger air jets to work with in the next week or so. i want to get everything that CB Performance has over 230.

well, let me start off by saying that i'm not using an EGT (i prefer them to Air/Fuel) meter - though i do intend to get one. however, when revving up under load, it starts to give a weird hesitation sometime after 4000 RPM. my tailpipes are only about 2 months old and they are BLACK and sooty as opposed to that dark brownish color.

 

I dont know about drilling it, but I was gonna say your pump jet. I was running WAY TOO rich before and found out that I was running a 120 for a pump! Moved it back down to an 80 and it was fine.

39 Venturies
235 Main/Air
80 Idle
Needle and Seat 300

This is my set up and its running fine, everytime i pull the plugs there beautiful mocha color. I have no clue of what im running for the emulsion tube. If you got it from RB and havent messed with it, it should be fine.

How do you set the mixture?

Hit me up on AIM, if you have it: i984se
-Ryan

 

just a little history ...

as i said, i bought it new in 1994. i used it for about 6 months because of some issues i was having with my engine at the time. i then drained all the fuel out of it and put it down.

i hadn't touched it until 2001 when i put this engine in the my current car. however, i have never felt that this thing has EVER run right since the install, but there have been too many other factors involved to condemn the carburetor as piece of crap. both my schedule and the fact that i spend so much time away from home contrbute to my not having much time to fool with the car because i can't afford downtime.

however, over the years i've made tuning improvements and i have eliminated other factors one by one (timing, tuneup, etc) and the engine still feels very lazy! so i'm becoming more convinced that the carbie is where my problem is, so that's my focus. i'm planning to go DLIDFIS as soon as i have some time, so weak ignition should be eliminated as a possibility soon.

i know the manifold is no good, but i think i'm still missing about 2000 to 2500 RPM and now i want it!

 

did you get it new or used? just asking to see if it was RB or a previous owner that put the 120 in there.

what mixture? idle? i know how to adjust the idle circuit with the two idle mixture screws. however, if you're changing accelerator pumps, then you must know that already. i'm sorry, just thinking out loud ...
if i'm able to adjust the main circuit, then maybe my problem is ignorance because i don't know how - other than changing jets.

however, that brings me to another minor issue i have. my idle screws keep backing out over time. if i were to find some stiffer springs, do you think they would stop?

 

wow great job diabolica1, this is the kind of dell site that has been needed. i was sick of always doing searches and turning up nill. my dhla 48's thank you.

 

smaller main fuel jets will lead out the whole powerband, especially the low to mid range. larger air jets lean out mid to top rpm range.

what altitude do you live at?

what color are the spark plugs?

installing an air/fuel meter will really help out tuning that dellorto.

although no one seems to want to hear it because it is pricey, best way to tune it is on a dyno with wideband O2 sensor. i tuned the dell on my bridgeport with 8 runs on the dyno and you're a lot closer to proper mixture than I was

 

yeah, i got sick of searching, too.
thanks for the kind words.

 

thanks for the tip on fuel and air jets. i didn't know that. now, i'm a bit more optimistic that the air jets will help out.

altitude? have no clue ... i'm in Florida, so i'm sure it's nowhere near Colorado or Tennessee. i can check and find a number.

the funny thing is the plugs always look fine (brownish), but that's probably because i only check them when i'm home and i have to drive about 200 miles to get there. i'll pull them this weekend and see because i haven't been home in about 3 weeks so it's all local driving.

well, to be honest, a wideband is in the works for me because i'm going to need one for my MR2 real soon.

 

one of my dell's came off a florida car. stock port 12a. 230fuel 230 air 39 chokes all factory RB settings header and presilencer and it ran just fine for him with those settings.

the dell on my repu is tuned pretty good and tailpipe is black. plugs are mocha brown.

 

how does it behave as you move from 4000 to 7000 RPM? are you using the stock manifold or a Lake Cities on the pickup?

also, i'm curious about how the one on your bridge performs. how much power did you put down on your best run?

 

any body with a dell runing a facet fuel pump or know witch one to use, any info?? looking at one part # 40131. thanks. 48 dhla stockport 12a

 

what's the output on that pump?
if it's the one that replaces the stock pump, then you'll need two of them to run in parallel (it's a volume thing). if that's the case, why not just try something bigger?

Carter, Holley and Mallory offer some great options.

 

i hear the carters have problems with maintaining constant pressure, holleys are too loud and mallorys are too xpensive. in my dell & weber book there is a facet and it looks tight. just exploring other options. still runing the stock carb with no problems. does 2-3 psi and 70 volume sound right?

 

stock carb or Dell? did you mean stock pump? they are fine for running the Dell, but the problem is sustained high RPM use. apparently they'll start to lag behind what the carb needs.

anyway, are those the specs on the Facet you speak of? forgive me. the Facets i'm used to were just stock replacements. it sounds like it can support a Dell just fine. my Carter is rated at 72 gallons per hour, so if that Facet can supply 70, you're golden.

i've been using my Carter for about 3 years now without problems, but then again i haven't been driving that hard. they're noisy just like the Holley pumps - my brother has a Holley on his Rx-7.

mar3 (our resident Mallory expert ) says the Mallorys are quiet and i think they flow something ridiculous ... like 110! i haven't used one, but they sound worth it to me. if my Carter ever fails before i go EFI, i'm getting one.

 

I had those back in the days. Two 6 PSI facet pumps connected in parallel. RB no longer sells them. Your best choice, if you really want facet, is the VW partshouse. I seen them at local parthouse except I never inquired about the 6 psi. You can make any pump quiet by using a a thick rubber spacer. In my case, I use a piece of rubber beach sandals.