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Dellorto DHLA questions!

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Hi guys,

 

Going triple Dellorto and at the moment I'm stripping the carbs before rebuilding them. I'm making this thread because I get the feeling I'm going to have a few questions about how these carbs mount, linkages, etc.

 

First question is this, what is in this hole?

20120628_165432.jpg?t=1340934550

 

While I was stripping them I found that 2 carbs have these screws covered in really hard gunky stuff while the third one is missing these screws (has the holes, but they are open to atmosphere). I assume these two screws are vacuum blanking screws like below but I just wanted to be sure I'm not missing some jets or something crucial.

7959.jpg

 

Also, just wondering how do the linkages work with these carbies? The instructions provided by Redline aren't exactly helpful...

 

Cheers in advance,

 

Alex

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Are you rebuilding these yourself?

Do you have any literature or manuals? I'm sure Scoota has whatever you need.

Do you have a sync tool?

 

As far as linkages go, they should be the same as any other triple set-up.

I can help you when you're getting that close.

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That screw is the idle by-pass adjustment screw it's an emission type dellorto. I do have the Des Hamill book and a sync tool if you would like to lend them!

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That would be very generous of you thanks Scoota, do you happen to have a picture of what those screws look like? I'm trying to order everything I need in one go so I can get these done asap!

 

Also would anyone know why these screws are covered in a gunky putty stuff? It is rock hard and to me looks like body filler. I know alfas are prone to rusting but surely the previous owner of these carbies didn't try to bog their carbs! :P

 

Are you rebuilding these yourself?

Do you have any literature or manuals? I'm sure Scoota has whatever you need.

Do you have a sync tool?

 

As far as linkages go, they should be the same as any other triple set-up.

I can help you when you're getting that close.

 

Cheers Simon. I'm getting the Des Hammill tuning/rebuild book on the weekend. I will be rebuilding these myself but the jets/tubes/screws/carb bodies will be professionally cleaned before assembly I think and I have a Unisyn but I'm thinking about getting one of the other carb balancing tools that fit into the trumpets... I forget what they are called!

 

The goal is to have the carbs rebuilt and in a somewhat drivable state before I get Gordon Dobie to tune her up :D

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He recommended just the stock 2000cc alfa jetting, which is what these carbs have and so do ashs (zr240)

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The hard gunky gooey putty set stuff is factory fitted, after car has been fitted with carbs, under it will be some form of progression hole air bypass adjuster.

They do not need altering once set, for that particular car it is tuned for.

It was an emisdions requirement.

 

Other thing it could be blocking, is a hole drilled further into body, to access another hole, again for the carb to operate as designed, and the blanking putty just seals it up, same as Weber carbs get little soft lead ball plugs to seal up drilled holes.

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After a bit of reading I found they are idle air bypass screws, and yes they are factory putty lol. I ordered some new ones to replace the flogged rusty ones I was given and I'll fit them with the new seal kit. Hopefully they don't cause too much of a fuss.

 

Thanks for the info on the linkage Mark, I'm assuming those wheels bolt onto the throttle shaft and the linkage rods attach to those?

 

Simon from where I'm sitting it looks like that style of linkage wheel doesn't fit onto the Dellortos, they have a rounded rectangular hole like the wheels Mark linked so I'm not sure they will work. I'll search closer and see what I can find :)

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Thanks for the info on the linkage Mark, I'm assuming those wheels bolt onto the throttle shaft and the linkage rods attach to those?

Yes they do, the wheels in simon's link do the same job!

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Well if they work you might have a buyer Simon! Once I finish rekitting these babies I'll have a chat with you

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Well the carbs are almost done, had major headaches with missing bits, non-matching other bits, broken other other bits and general wear that should be expected from old carbies that have been sitting on a wrecker's shelf for a few years:

20120724_164136.jpg?t=1343112900

 

I won't be using a return line on these carbs so I was wondering what I should do with the stock return pipe that is chilling in the engine bay, just block it with a bolt+clamp?

 

Also does anyone have any tips for when I bolt these on and try to get the car running? I have wound the idle screws all the way in (full rich) and am going to back the distributor off to avoid any potential pinging/damage caused by whacky mixtures, any other recommendations?

 

Thanks in advance

 

Edit: Has anyone else had issues with their linkages touching the carb body? The first thing I thought of doing was to either cut the offending piece off the carb body or cut the thread on the rods to get everything to clear, but that seemed almost counter productive. This protruding bit where there is a hole for a bolt of some sort is the offending part:

20120724_153221.jpg?t=1343114752

(I won't be using the Redline linkage wheel but I figured I might have the same issue with any other type of wheel I could potentially use)

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I would turn all the screws out to three on start. 1.5 is a minium 5.5 is a maximum and if you can't get it to idle in this range you will have to rejet idles.

 

You may have problems bending float tabs without a return but give it a shot!

 

Are you using soft mounts? I would.

 

The wheels have a tab for idle adjustment. I had to cut the pivot joint bolt down too.

 

 

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The wheels have a tab for idle adjustment.

Do you mind explaining what you mean by that? Looking at the wheels they just bolt on and that's it.

 

I have some soft mounts that will be used when the carbs finally go on the manifold for good.

 

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Alex

 

I hope these photos explain a little with return spring mount (home made) and throttle link arm. The arms I found at a carby store.

 

Mick

post-669-144023682603_thumb.jpg

post-669-144023682614_thumb.jpg

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Bit of an update...

 

I bought some of the linkage wheels similar to what Scoota has on his carbs and the ones they sent me won't fit the linkage properly because they are the wrong side of the carb body. I'm hoping the seller can help me out and get me the right ones.

 

Also I don't have idle adjustment screws in those little holes on the carbs... or a thread at all on one carb. If I was to use loctite on the bolt would that be enough to hold them in place? Or should I be on the lookout for an appropriate spring and washer to hold the idle adjustment bolt in place?

 

2 steps forward and 1 back... They better be worth it!

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I think a picture would help. Idle adjustment bolts on your carbs are probably held in by nuts under the tab and a spring on top. Nuts and springs of a specific size.

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Photos you shall receive! Carbs 1 and 3 have holes which look like this:

Bottom view (threaded section on bottom)

20120814_124746.jpg?t=1344917170

 

Top view (larger unthreaded area for I assume some sort of insert/spring retainer)

20120814_124802.jpg?t=1344917248

 

Carb 2 bottom view (big unthreaded area on the bottom with smaller unthreaded area on top)

20120814_124704.jpg?t=1344915609

 

What is on the opposite side of carb 2 and I guess what should be in the other side:

20120814_124738.jpg?t=1344917580

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Carbs are on, I wrote a bit of a summary in my build thread but to summarise the summary:

 

The car refuses to turn over and when it does it backfires through the carbies and dribbles fuel through the trumpets. The vent hole has no fuel in it so I don't think it's the float levels and the jetting is stock Alfa GTV2000 as run by several people on this forum so I don't think it's the jetting.

 

It's an L28, F54 block N42 head with 280ZX distributor, near new spark plugs, leads and ignition coil. The carbs have no return line and are being run on a low pressure high volume fuel pump as recommended by EFI Hardware for a Zed with triples (tiny Pierburg thing).

 

I think it's timing but I'm all ears to any other possible reasons that could cause my car to do this.

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