Dellorto 36 drla hesitation

[Vw1600dellortoGR]

Hello , i am running a pair of dellortos 36 drla, and i have a hesitation at about 2000-3000 rpm when i accelerate a bit quickly, It happens much more when cold, but it is also present after the engine haw reached temperature. The emissions analyzer(static) shows that the engine runs lean at higher rams even though it is a 1600 and has 130 main jets.

[nextgen]

Well it does sound like it is starving at those RPM's. Or it can be your timing.

I have a Mallory Unilite that I can set the timing at 12 degrees at idle and 28 at top RPM, s . The higher the the stock 10 at idle gives me a great idle and the 28 that is lower then the stock 32 gives me smoother transition into top end. Try checking your timing. But go to a 135 mains see what happens, you can alway drop down to 133 if it proves to rich.

I had a similar problem and went from 128 to 135 and it went away. Then dropped to 130 and it was still fine. So even 2 points made a vast difference.
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[67rustavenger]

Since this is a dead thread. I thought I'd use it. Instead of opening a new one for a similar issue.

Little back story. I have had these same carbs on the engine, 1679. and they were tuned perfectly. No hesitation at all.

The engine idles perfectly and the carbs are in sync. Checked them twice with a snail sync.

Jetting is (Del jets) 50 idle, 130 main, 185 ac, .2 emulsion tubes.

I can drive on the idle circuit smoothly.
When the progression starts. The engine stumbles and has very little go. If I put my foot in it, the engine will accelerate at WFO. Not allot of fun driving that way.

I'm pulling all the jets and blowing them out. Hopefully there is some blockage that is preventing them from working correctly.

Any idea's?
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Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
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[67rustavenger]

Never mind.
It was a clogged jet. I shot them with carb cleaner and blew them all out with compressed air and it cured the stumbling issue.

Have a great day!
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[Danwvw]

Yeah, Dellorto Idle jets will clog over and over if there is any foreign matter in the fuel at all.
They progress from idle to mains a little lower in RPM than 3K or 4K though, I don't know maybe not with a stock cam and a low compression 1600.
It could be that is accelerator pump circuit problems. The first thing to do is to remove the carb and give it a good cleaning and set fuel float bowl level. New Orings the right ones on the accelerator jets too. Clean the accelerator pump output check valve, they often have deposits and this allows the fuel to drain back so they cause a delay on acceleration, you will notice it on the highway.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[67rustavenger]

Thank you for the suggestions Dan.

The carbs have a proper set of O-rings. They came from a carb rebuild kit.

Floats were last set at 6mm. Fuel pressure is 3.5 psi. Regulated with a Holley regulator.

I had it running well earlier today. But while driving to get some parts in Portland a jet clogged again. I have just gone through all 4 idle jets again and test drove the car. It's still not 100% right. So I'll go through the main stacks again and see if that clears things up.
If that doesn't fix it. I'll pull the carbs and install the old 40 IDF clones that worked pretty good while I wait on new rebuild kits. The kits in them now are under 6 months old. But you never know.

I have a metal bodied fuel filter under the car. Not the cheapo plastic things that everyone seems to have on their cars. Hoses are new by a month.

Gas is fresh. I filled the tank this morning and it usually takes a week + to burn one. I daily drive the car.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[Danwvw]

I had a lot of trouble with Idle jets clogging on my engine in my bus when I first installed it. I think a little dust got into the carbs maybe hooking up the fuel lines. Must have cleaned the idle jets first this one then that one 10 times before it settled down. Same thing going on another engine I have with Dells. There is a part called the Jet Doctor $15 which I have not tried yet that is supposed to fix it.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[nextgen]

I have jet doctors and still get clogged jets, but now only 75% better. Has got to my my Dells are not sealed correctly.

pros --- less pulling jets to clean

they sit higher so easier to clean

Cons Very thin an metal, have to fit a flat head screw driver in perfectly or you can damage the Doctor.
_________________
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The TYPE IV UPRIGHT CONVERSION MANUAL
BEETLE MAGNETIC DEFLECTOR SHIELDS
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[67rustavenger]

I tried jet doctors.
They caused the engine to idle so low it was difficult to drive.
I had to constantly pedal it at stop lights and signs.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[67rustavenger]

So the clogged jet issue has subsided and the engine when warm runs great.

The latest issue is cold starts. The engine acts like it's running on only one carb. Until the engine is warm. Then it seems to run as expected.

I spent last Saturday re-jetting the carbs while reading the results with an MTX-L wideband.
Before I started re-jetting. I noted a very lean AFR reading (16+ at idle).
Idle jet was .47
130 main
185 AC
.2 emulsion tubes
Timing is set at 15° BTDC. Verified with my laptop via the data connection on an MS-Digital distributor.

Long story short. You can read the procedure in the "Wideband Results" thread.
I ended up with a AFR at idle of 14.6 - 15.7.
Cruise at 2500 rpm AFR was 15.to 16.5.

The issue now is starting as noted above. I have an electric FP and let it run until it stops to fill the carb bowels. Pump the pedal a little and turn the key. The engine stutters to life and runs super rich.
I'm puzzled as to why this is happening. When the carbs are jetted lean.

Anyone have any ideas?
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[Danwvw]

I have been chasing a missing at idle problem that seems to get better after warm up. It was always the same cylinder. I changed the Dells for Webers but the problem persisted until today.
Today I got may ohm meter out and started checking spark wire resistance. Turns out one of the resistive plug connectors was intermittent.
The thing about a 1600 is it will need 28mm venturis. (The fuel bowls must be over filling on yours for some reason. Things are pretty tight in there the floats drag against the sides real easy on dells. Got to get that happy with them off the engine and all the gas drained and dried of gas and using a length of unused fuel line or something clean you can blow on with your mouth and play with them turning them slowly upside down and make sure the float valves always shut properly. Next you can install a carb top gasket that has a hole in the right place so you can use the stick of your digital calipers to measure actual gas level with the carb on the engine. This is tricky as the stick will hit the float and let more gas in and you will get high readings when that happens. It's tricky. Your'e looking for gas levels there of about 30mm.

_________________
1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[W1K1]

Pull the main jet stacks, you need to drive on just the idles to see where your jetting is on you O2 gauge. Turning the idle screw can get you 10 - 16 AFR at idle with a handful of jets.

you need to see what it's reading under load, not cruising part throttle, or at idle.
does your MTX allow logging so you can see the performance after? it's hard to watcha gauge to see whats happening while driving
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[67rustavenger]

I did the whole jet stacks out thing. Got that figured out.

This is an idle circuit issue. Not load issue.

At WFO I get a reading of 11.2. Yeah I know it's rich. But ATM I only have the 130 main jet.

Thank you for your input.

Dan, the floats move freely on the bowels. I did a similar check as you describe.

It's not the ignition system. This issue is with the carbs, as I have completely changed from an 010 distributor to an MS-Digital distributor.
The spark plug wires are 8.5mm and the plugs are the resister type, as required by the Cb installation manual.
Thank you for your input as well.

The carb sync is set correctly. I have checked them many times. Including this last weekend before re-jetting the carbs.

I have also changed the FP from mechanical to electric, still utilizing the Holley regulator. The pressure reads 3 psi.
_________________
I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!

There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo!

[Alstrup]

What about just buying a set of PROPER air cleaners.
When you prepare the carbs for installation think CLEAN CLEAN CLEAN.

The only times I have had problems with clogged jets and regular good cleaners was when the cars (typiucally buggies) ran a lot on the beach or similar off road. On those I simply installed dual layer filters. End of story.

T

[chrisflstf]

Crud can stick to idle jets that carb cleaning and compressed air wont dislodge. Look at them under some magnification and make sure the hole is 100% clean and round. May need a small abrasive brush to dislodge stuff