ducktape

Need some advice on my DHLA setup.

I managed to solve my timing issues, and got the car to start for a second or two, but it appears to flood pretty quickly. Motor is a street port 12a.

Here's my carb specs

Dellorto DHLA 48 side draft

Main: 230
idle: 75
pump: 80
venturi: 35
MAW air 230

internally regulated CB performance fuel pump @ 3.5lb

What should I change?

t_g_farrell

iTrader: (1)

Your pressure is still too high, It should be around 2.5 psi, anything
above that will flood the bowls.

Also take a look at www.gruntled.com/Dellorto for SP jetting recommendations.

Siraniko

iTrader: (13)

check your float/need & seat. something it causing it not to close

ducktape

Bought an adjustable regulator today. Will let you know how it works out.

DarrenTRS

iTrader: (1)

Steps to see if your flooding the engine due to float issues, I had the same problem and figured it out this way.
1. Take filter off so you can see directly down the barrels
2. Turn key to ignition so the fuel pump is running.
3. Look down barrels for a good 15 seconds and see if gas begins to pour out of the main jets into the barrels, if so then your overflowing the bowls and the fuel is draining through the 2 small holes in the side of the [jet tower?].

If it does turn out your flooding because of that then I would suggest taking the steps to de-flood the motor before trying to start it again because any gasoline pooling in the back of the barrels at the base of the throttle plates will get sucked in upon restart and possibly flood the car again.

As well here are mine for a stock port GSL-SE 13B:
Main Jets: 2.2
Main E-Tubes: 7772-8
Idle Jets: .75
Idle E-Tubes: 7850-8
Starter Jet: .95
Starter E-Tube: 7482-4
Pump Jet: .80

As well I was stumped for nearly 2 months because of what I thought was a carb issue which turned out to be a vaccum leak between the carb and the RB upper intake manifold so my advice is as well, make sure you don't have any vaccum leaks or loose bolts.

ducktape

Ok, I got it started... The adjustable FPR seemed to do the trick. BUT, The odd thing is, the car will only run at .5 psi indicated on the FPR and with the air-fuel mixture screws all the way in. And it's still rich as hell.

I checked the float levels using a ruler, not very precise. Guess I'll try the "look for the drip" method.

Any suggestions?

ducktape

http://www.youtube.com/watch?v=PNF2eeoUg9E

Siraniko

iTrader: (13)

turn up the pressure again and inspect the barrels for drips. if it drips above 3psi, check your needle and seat for debris and such. if its ok, then attack the float.

DriveFast7

iTrader: (1)

What kind of FPR did you get? Did you buy the cheapo dial kind where you turn a round **** to the PSI number you want? If so those are terrible.

Do you have a fuel pressure gauge? They are truly invaluable. I bought this one which is very accurate, love it. http://mrcmfg.com/catalog/product_in...roducts_id=163

The idle mixture screws should be 2.5 turns out once it's all tuned right. Idle fuel jets right, idle speed right (not too high or low. 1000rpm is a good idle), floats right.

If you turn up the idle rpm using the flathead screw facing the rear of the engine, then you're running on the progression circuit which would require you to turn down the idle mixture to lean it out.

Have you checked the jet sizes with a jet gauge? Some people drill them larger than the # stamped on them. http://www.piercemanifolds.com/accessories.htm

Congrats on the start up

ducktape

Still haven't been able to get this thing working right.

With an appropriate idle jet (75-85 range) the motor would cut out like crazy right at 2500rpm, even in neutral (no load). The only way I could get it to transition to the main jet was by hogging out the idle jet to 1.15, which is blowing-clouds rich. ~10.5 AFR. No idea why this is...

No combination of air correction/main jet has gotten the car past 5000 rpm on the road. If I hold about 1/2 throttle, it will pull up until about 5k, then goes lean. Push past 1/2 throttle, and the AFR meter pegs lean, and the engine just stops running. I was beginning to suspect the venturis may be too big, but then something odd happened:

I was driving down the road at about 4500rpm, 1/2 throttle and the engine was beginning to cut out... I entered a left hand turn, and it pulled to 7k like a raped-ape. AFRs were lean, but it found enough fuel to move it's *** for the first time. This behavior is repeatable, it will do it every time. I suspected fuel slosh in the tank, but the pickup is on the left side of the tank so that's not the cause. I tried staggering the floats thinking the idle bowl was filling up closing the needle while the main bowl was empty... It had no effect. Do I need a larger diameter needle/seat?

I'm at my wits end. I've tried every combination of idle/main/pump jets I could and haven't had a bit of luck. Suggestions, anyone?

thielepr

I had almost the same problem before. 2.5 psi is perfect . But in my case it was a good cleaning of the dellorto that fix my problem.

t_g_farrell

iTrader: (1)

Sounds to me like your floats are set too low. Normally on right hand turns in a 7
the Dell will stumble, this is because of slosh in the float bowl which causes air to
get sucked into the main jets. The fix for this is to adjust the floats a bit higher
than spec. Now in your case its going good on a left hand turn, so maybe your
floats are too low and when the slosh happens it drops the floats and you get
plenty of gas. BTW, 2.5 psi is what you want for the pressure, no more
no less.

ducktape

One thing to note my engine is "backwards", as it were. So if it were in a first-gen the car would pull like a bat out of hell turning right, and stumble turning left or going straight.

t_g_farrell

iTrader: (1)

Other way around, stumbles on right turns, fine on left turns. So yeah probably have to reverse it in your case.

MACCHINA

Hi everyone!

I'm in a situation here. I bought a half bridge ported rotary engine from USA (I live in Brazil and rotaries are an "alien" thing here). The guy who helped me to search for the engine also sold me his Dellorto 48 DHLA "C".

I stripped down the carburetor in order to clean it and when I checked the float level I had a surprise: 24,30mm without compressing the needle spring!!!!

I thought it may be because the engine is half bridge ported, or maybe the carburetor might be used in a turbo engine before.

Can anyone give some explanation?

I need to set this carburetor as close as possible to a point where I can get the engine running, even not perfectly.

I'd like to know if anyone have seen floats with this level before.

Thank you.

t_g_farrell

iTrader: (1)

You measure the float drop by holding the top vertical and the floats just pushing on the center
sprung needle in the seat using the float weight. I'm not sure what measurement you are referring
to. Also make sure you run the right psi, 2.5 should be golden.

The other issue is you will have to retune that carb for a half bridge. Hopefully you can get it to idle but it will probably be too lean otherwise.