Hello Folks, Due to various leaks I'm rebuilding the DRLA 36 carbs which came fitted to our van when we bought it 2 years ago. I had no idea of what jetting was inside - the PO told me it was tuned for maximum economy, and had it rolling roaded. However, I suspect he did a lot of back road driving, whereas we do a fair bit of fast motorway driving. A VW specialist garage worked on the van in 2013 and converted the mechanical fuel pump to electric at my request, amongst other jobs. They also fitted a fuel pressure regulator. However, I'm beginning to think they were more used to Webers as I found all the mixture screws 1.5 turns out, and the fuel pressure set to 2.5 PSI (measured). AIUI, Dells start off around 3.5 turns out on the mixture screw, and should have 3 PSI fuel pressure. As a result, and combined with the jetting below, I think the engine has been running too lean and too hot. Power/performance on long fast hills has been very bad recently, with the van seeming to run out of power - though it was fine around town. I'm looking for advice on a good set of baseline jetting to help avoid running out of steam on hills. Engine - 2L type 4, CJ code. Automatic transmission. Twin DRLA 36's. Here's what's marked on the various components. I don't know whether the jets could have been drilled out though. Main Venturi 30 Aux Venturi 100781 Main Jet 122 Idle Jet 57 Pump Jet 33 Starter Jet 80 Main emulsion 9164.1 Starter emulsion #3 Air Corrector 175 Needle valve RCA 1.5 Thanks & goodnight!
I'd agree - my 2 litre with DRLA 36s has mains = 135 idles = 65 airs = 185 The linkage and idle jets make the most difference, as the majority of the time you are part throttle. There isn't a 'right' answer to this question thou, so if it ran before, rebuild them as they were, and hit a rolling road ASAP. You can then see the fuel / air ratio across the rev range and tweak from there. Also 36s are a tiny bit small for a 2 litre, so you will eventually tail off at higher revs, as they cannot get enough air in. Great for torque however, which is the better compromise for a heavy old bus.
Thanks chaps. Any thoughts on 9164.1 vs 9264.2 emulsion tubes? From what I've read in the Superperformance Tech Book, the .1 gives more low speed enrichment than a .2 - perhaps compensating for a smaller main jet? That said, the pictures of emulsion tubes in the book don't match this:
in the superformance book is says ...tall airs 180 55 idle jet and .2 emulsions as for 36`s being too small for a 2litre i don`t agree really as if you run a 30 vent on a 40 or 36DRLA then its the same ..... i think 32 vent is the biggest that will fit a 36
I have for sale I have 4 x 9164.3 emulsion tubes for sale of you need them. I took them out my dell 40's
Comparing my actual emulsion tubes (marked 9164.1) to the image above, the two very top holes (of which only 1 is visible in the picture) appear to have been brazed (not soldered) - converting the tube to a 9164.2 ? It's a very neat job - other than a slightly darker dot you wouldn't know. I suppose I'd need a jet gauge to measure the actual main & idle jet sizes? Anyone got a set?
Thanks - but it looks like mine are .2's in reality. Out of interest what did you replace your .3's with?
I started a thread a while back check it out ! Jet sizes for Dell 40's on a 2l Type 4 engine. 180 should read airs
So, I ordered a jet sizing tool and two new floats from Eurocarb. Bye bye £116... I bent one of the floats out of shape so it was sticking somewhere inside the carb body and created a lovely petrol fountain. At least the carb wasn't attached to the van. I *think* I've fixed the float, but now I don't trust it.
emulsion tube designs have changed a bit for both webers and dells.....the ones that came with my new Spanish IDFs were 'correct' but badly machined compared to the ones in my old Italian IDFs....duly replaced. I'd spend some time balancing all four carbs in terms of vacuum, before trying to compensate for any discrepancies with different tubes....
I think you're right @vanorak. TBH, I just want to get the engine running again so I can drive it back into the garage so it's out of the rain and better secured.
if you get both sides balanced, the linkage spot on (set it while the engine's hot) and the idles pretty close, it'll tune up reasonbly well on the mixture screws...certainly well enough to drive it around....it just may not be as good as it can be, for which you really need a decent rolling road
It's a black art isn't it. I ran 165 mains on my 1600, it did 28mpg on a run and the big jets kept it a little cooler I'd guess. In my experience it's not a problem to go a bit heavy on the mains. Much better than too small.
