Installing Dellorto DRLA 40's onto Type 4 2.0L Motor

Discussion in 'Mech Tech' started by andyo, Jul 11, 2012.

  1. Hi All.

    I am to move from a Weber DFEV Progressive to Dellorto DRLA 40's on my Type 4 2.0L Engine. The idea is that this thread will both document that transition and answer the many questions I have, also (hopefully) provide information to those that wish to do the same.

    UPDATE 2014: The carbs that I ordered (Alfa) did not arrive, I lost interest and now have bought a refurbished pair from eBay. Again these are Alfa.I have updated the information below and will continue to edit this first post with more up to date info.

    All my photos available here:

    As follows:


    Please see the manifolds that I purchased - £25. Not ideal as they inlet is bigger than 40mm, I can always change these later.

    [​IMG] [​IMG]

    Need to buy 4 gaskets:
    3mm Spacer for DRLA, IDF & IDA 48mm - £3.07 each
    Slimmer Manifold Nuts
    Have been advised that these are desirable - Euro Carb

    Carbs and Jetting

    Please see the carbs that I have purchased below:

    After some research I will start with the following jetting (then Rolling Road):

    Eurocarb very kindly gave me loads of advise, they recommended the above set up with 30 Chokes, as I have 28 Chokes already they gave the second set of advise.

    UPDATE Feb 10th: I now have 28, 140, 58, 180, 9164.2 and 33's installed.

    Emulsion Tubes Modification

    Although I planned to start with 9164.1 emulsion tubes, I was told by Stateside that this would be a waste of time and that 9164.2 are a 'must have' for VW engines (they didn't have any 9164.2 in stock AND their expensive). So, I decided to convert my 9164.1's by soldering the top holes (there are two) - please see thread no 56 on this thread to identify which holes. Found that plumbers solder was no good, so heated up the emulsion tube with a gas torch and used electrical solder. Once I had a 'blob' I filed and went through the grades of wet and dry. Seemed to work well - time will tell and it's up to you if you want to do it the same way, very little info available on the web as to the best approach, some pics:

    [​IMG] [​IMG] [​IMG]


    From research CB linkage is in preference to a CSP one. When talking HEX Bar. From the information provided to be in this thread it was suggested that a Bell Crank would be a good idea, in preference to HEX bar, so I am going for this one:

    MAchine 7 advised the following:

    I have also been picking the brains of 'olnow' on here as he has already done this (again a very helpful guy) his advise:

    See purchased list, went with ones from StateSide Tuning, seemed very reasonable.

    See purchased list, wasn't going to bother but have been informed they are a good idea. But at £8 each from Stateside thought I may as well.

    Crankcase Pressure
    Now I also understand that the addition of twin dells can increase crank case pressure, so some people fit breather boxes, I understand, which also get bad press. Elsewhere I read to simply vent into the top of the air filter. I need to look into this more and will update this post with my findings.

    Fuel Pressure

    It has been suggested that with a manual pump I should be OK, many will have electrical which may need restricting, a good thread on here should help if you suffer with this issue:

    What else is needed?
    Do I need to fit an anti pluse valve for my SVDA dissy? YES - £12 ish from eurocarb. - See Purchased List
    Is a manual fuel pump OK? YES.
    If so do I need to restrict the fuel pressure in some way?
    NO, only for elec fuel pump

    What I have purchased to date (other than carbs and manifolds) - 05/02/2014

    My Carbs
    Because I have Alfa carbs it seems the chokes need removing and the extra two studs drilling and fixing in for the air filter (as advised by lhu1281 :thumbsup:). Good information on how to do this is here:

    Last edited: Jun 8, 2014
  2. Manifolds are correct and not off set ... jets seem ok i personally would go 30 vents

    I have done this from scratch so any q`s or pics let me know

    you will need anti-pulse valve and manual fuel pump is fine as it is with no restrictor

    I have the CB linkage fitted which comes with filters and altho its not fantastic is plenty good enough

    your carbs look like they are straight from an Alfa so will need the chokes removing and the extra two studs drilling and fixing in for the air filter .
    note special arms to allow for the fine adjustment of the carb

    i bushed the end of the CB linkage

    brake servo take off

    5mm bakelite that sits between manifold and carb to prevent the fuel boiling when you stop


    fuel tank and crank case breathers
  3. Many thanks for the detailed reply lhu1281, of course I have loads more questions!:

    • Yours is a type 4 engine, correct?
    • Where did you get your CB linkage with filters? Do you have a link?
    • I have heared that a crankcase breather is imporant, which one did you go for?Are those bakerlite gaskets easy to get hold of?Why did you bush the end of the CB linkage?Those special arms to allow for the fine adjustment of the carb, were they included in the kit?
  4. yes mines a 1700 type 4 36 drlas
    Can`t remember where possibly machine 7 or custom and comercial (one of the big suppliers )
    crankcase breather is just pipe from case to homemade jobbie in filter but any aeroquip or barb fitting will do .
    bakerlite /tufnol gaskets wre again home made but Stateside tuning do them .
    bushed the end of the CB bar for longivity /i may have had to shorten it as well .
    The arms were again wire erdoded stainless steel made by me .. i may have spare pair

    Mines been on and running for 3 years with no problems ..
  5. This is a fantastic thread as I am looking at doing the same. I have a pair of 40s manifolds and linkage but the linkage is a bell crank affair which looks a bit poor. Got the filters. Bought all together some years ago fitted when I put my current motor in but had a few issues and reverted back to the DFEV!

    This may, as I say, spur me on to crack on with the job. My manifolds look similar to Ihu's but no servo take off there! I did fit a breather connection with liquid metal which drew air in so looking at a proper solution for that - did you take off from both sides on yours or just one?

    Anyway will drag it all out andremind myself what I have. Advice I took at the time was to fit 32 vents but I think from discusions recently that 30s are the way to go. I also have some 28s so unsure whether to fit with what I have and then try different set ups!
  6. Oh yes- mines a type 4 2 litre.
  7. well mines a 1700 and i started with 30 vents then went down to 28 and much better
    I tig welded both manifolds for servo take off as per og solex`s
  8. 30 chokes are a little on the small side... I'd be looking at some 34s based on inlet valve size
  9. Really! On a standard 2 litre? Im usually fully loaded and need some good bottom end to get things going (Viking roof and interior and 3 women with associated chattels!)

    I have 32s!
  10. Hi,
    'the cb website mentions staggered fit' - all type 4s have staggered fit. As i recall the left hand bank of clyinders is in front of the right hand side. In order that the carbs both open at the same time and (importantly) rate, the bits of the linkage have to form the same angle between throttle shaft (end of carb) and cross bar linkage arms. In reality, this means the uprights with the ball and sockets on have to be as upright as possible. CB achieve this by including an extension that fits horizontally between the throttle spindle on the left hand carb and the upright.

    Took me ages to suss this out. I will try and find a diagram to help...
  11. [​IMG]

    The bit mentioned above is circled in red - when on the engine, this points forward, hence taking account of the staggered nature of the barrells and pistons.

    You can fit without, but the two carbs will then open at different rates, and one side of the engine will hence be fighting with the other. Not ideal...
  12. You're welcome!

    Thats the linkage kit I've got on my ex Alpha DRLA 36's (on a 2 litre).

    One other thing to watch, the 'arms' (throttle one in middle and carb ones on the ends) are secured to the hex bar by allen key grub screws.

    These are the weak link, as they can come loose. This then ruins your idle / throttle opening. Its a good plan to either use a suitable loctite / glue, and / or check regularly.

    Thats the only issue I've had with this kit, been on the van 6 years now.

    BTW if those pictures are your actual carbs, the chokes have been blocked already, so one less job!

    I would also heartily reccommend going to a rolling road ASAP after fitting. Best bit of money you will ever spend for your van, and will maximise all the outlay on expensive carbs and linkage.
  13. Paul , The discussion about vent sizes will go on for ever ... Doesn`t a 2l have smaller valve sizes than the 1700 ? i can`t remember ..I know for me with 30 vents you had to constantly rev it to pull away with a big dead spot till the revs got up , swopping to 28`s (124 mains 55 idles) sorted all this ... but then i rarely rev it much past 3500rpm during normal driving (its ony 1679 cc ;D) and she drives so well now for a fully loaded westy ....

    ref the grub screws just drill and stick a second one in ...

    one othe thing if you look closely i had to clearance the manifold for the head stud nuts but as yours are different manifolds chances are they will be fine
  14. Yes, that picture shows the block off plates nicely

    Just to show why a trip to the rolling road is essential - the choke recommendations vary within this thread. There is no right answer, as all set ups will vary.

    Your selection looks spot on to get you up and running - for the record, on my 36's I run

    185 airs,
    30 vents
    135 mains
    and 65 idles

    Bigger chokes will give more top end, limited by the intake system (ie valves and heads - as Paul Weeding mentioned), at the expense of reduced torque lower down, so normally people suggest smaller is better here (as per lhu1281s experience)

    My 2 litre achieved a nice smooth air fuel ratio across the rev range, and topped out an approx 95bhp at the flywheel. My engine runs out of puff at this point, mainly due to air intake (carbs are too small, valves , head flow etc). Still, standard is about 70bhp from memory, so I'm very happy

    Ref manifold nuts, you can get some 'special' jobbies, which are a spanner size down for the same size thread to achieve the same result
  15. 95bhp at the flywheel << 8)
  16. If I get anything like that on my 2 litre I will be a very happy bunny.

    I also have one of these to fit. (the silencer that is - not the rug!) Unsure whether it provides and tuning benefit tbh.

  17. Mmmmm. Lovely Dellortos :). When they arrive, you'll want to lick them...they're mechanical masterpieces. I've got a pair in the garage waiting to go on. I fondle them from time to time...

    As above, the chokes - actually separate cold start jetting: Dells don't have anything as common as choke plates - do appear to have been either plated over, if they're Alfa originals, or just missing, if they're later aftermarket ones.

    Believe the 40 DRLAs were fitted to Alfa 33s. The smaller 36s were fitted to Alfasuds.

    PS Worth getting the slimmer manifold nuts - dellorto uk sell them - to give a bit more spannering room.

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