DRLA 40's - 1 barrel half the air flow of the rest

I've finally installed my carbs and I've been careful to set the plates, floats, mixture screws etc all sound before hand.

The van runs and idles fine, but a little lumpy. I've got the idle set to about 900 and I've been trying to sync the airflow with my snail gauge. I got barrels at 2 and 4 set first, and both are pulling about 5. Barrel 1 is the same, but barrel 3 is at 2.5. How the hell can that happen? I was expecting to maybe tweak them a bit but it's half the flow!

Any ideas chaps?

Thanks

Paul

 

Is the throttle shaft bent on the 3/4 side, so that the throttle plates aren't opening evenly? A poss. Also...are all the air bleed screws (if you've got them) at the base of the carb set the same? As I recall, you can get about half a notch (or a bit more) on the snail-o-meter with the air bleed.

Best to shut them all completely, do a basic setup, then use them for final tweakage.

 

The air bleed (bypass?) screws are all fully seated. When I set the throttle plates to 0.003", I checked the ones opposite the throttle mech too, just out of interest. That one did have a difference, but it was literally only 0.001". That wouldn't halve the air flow would it?

 

What about something mechanical like a tight tappet

 

There is obviously something physically wrong either bent ,loose or damaged . Try to compensate with the bypass screws ....mine were pretty much bang on ....

 

leaking manifold gasket or servo take off

 

With my 40s I found 3 thou a bit too much - idle was up at about 1200. Even a thou can make a difference, I found. You might have a slightly bent shaft. Worth checking again with your feelers, I reckon.

 

Yeah initially mine was around 1300 so I turned them both down till I got to about 900. Got the carb off now so will check for twisting etc. Also just noticed that I didnt set the accel pump as nothing comes out when you move the throttle! Good job I'm taking them off eh

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Give 'em a good look over, sure you'll sort it. Worth persevering, as Dells are absolute pussycats - their only mission in life is to meter fuel to your satisfaction . With everything sorted and a proper snail meter, you can have them balanced in 20 minutes.

 

<edit> Actually, when you're setting your idle mixtures, their only mission in life is to backfire and set your eyebrows alight...

 

Well its better. The plate was open just over a thou more then the throttle link side, so it looks like I've got a slightly twisted bar. Tried to make slight adjustments and got it within half a thou. Air flow is now within 1.25 of the others, so that'll do for now I think

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Can you take the difference out with the air bleeds?

 

No....I took one almost all the way out and it didn't drop enough. I'd have to have all the other 3 leaking maximum to get near it

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Well I took her out for a run today and I can't believe the difference! I haven't done the mixtures properly yet so it's running rich at the moment (sooty plugs) as I've not found my colourtune yet

I know it's defo pulling quicker from standing, just driving it normally, as my cupboard door now flies open if you don't gently press the pedal!
Went on the motorway and it'll sit happy at 70/75 with 3/4 pedal. Before I'd have to have foot to the floor. Also, I now no longer slow down on hills (well....only a couple of mph) before hand I'd be down to 50 on some hills.

So....next plan is to find my colourtune, then I might go for a rolling road session. But I might wait for that as I've been eyeing up j tubes and a ss exhaust....but need to wait for funds

 

What size engine have you got?

 

Its an 1800 AP engine, but I made it fit in my T25

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A pleasing size . I've got a 1776, which flys along with the Dells. They're also running rich at the mo, but I can't be bothered to tweak them. They drink petrol like it's going out of fashion, but worth it. Every hill's a third gear hill!

 

Do you know what jets etc you've got? I've got the following:
Choke 30
Emulsion tubes 9164.2
Air correction 180
Mains 125
Idle 60
Pump jet 40

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28 venturis
9164.2 emulsions (9164.1 with top hole soldered up)
57 idles
118 mains
180 air correction
35 pumps

 

Cheers mate....in the same ball park then. Did you put yours on a rolling road?