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Discussion Starter · #1 ·
Greetings,

I just tried to have the Dellorto DHLA 40H carbs in my Alfetta GTV2000L properly calibrated and this resulted in one adjusting screw being utterly destroyed; it was stuck at almost the bottommost point of the thread and it was quite impossible to move it. That carb (rear) is as good as dead, I'm afraid, and of course, proper calibration proved impossible.
I have a pair of Dellortos freshly rebuilt, intended for my other Alfetta GTV, but ready to be installed into my daily drive. Yet I discovered these are 40Cs. I read here on the BB that C-s are performance units and H-s were intended for good emission, but that's all I know about them. On the outside, the only visible difference is a small hole on the 40Hs which is covered on the rear carb and on the front carb it is connected to the distributor. I was told it affects ignition timing. (The 40Hs also had a solenoid mounted at the center to affect idle rpm, but that feature had been removed earlier.)

I really want to find a solution to the carb problem ASAP so the way I see it, I have the following options:
A) Install the 40Cs and don't worry about the distributor connection. Plug the hole shut on the distributor and that's it. Some HP and emission loss will follow, but I can live with that.
B) Pair the front (undamaged but also un-rebuilt) 40H and the rear 40C (rebuilt), with matching jets, of course. But I don't want to pair an un-rebuilt carb with a rebuilt one.
C) Don't do anything until I can get new 40Hs. Yet, as I said, I need the car very soon.

I'm leaning towards option A). Any insight, anybody?
(One more question: these Dellortos have a small lever at their bottom. You can set this lever via turning two bolts, but only before they are installed; due to their position, they are virtually impossible to get at once the thing is in the engine compartment. I couldn't find anything about their proper setup, so after rebuilding the carbs, I put them back the way they were before disassembling. Is this important?)
 

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Discussion Starter · #2 ·
Update...

Well, not knowing your way around carbs is one thing, but no being able to read... it turns out the rebuilt set isn't a "C", but a "G". At least it's closer to "H". I presume these things were produced in alphabetical order.
Anyway, I installed the "G"-s (plugging the distributor connection intended for "H"-s) and the engine run reasonably, until I realized that the underside of one carb is GUSHING petrol. I don't understand it, I put it together with incredible care. Maybe a seal was faulty, maybe I messed it up. Nevertheless, I'll have to get them out again.
I turned my frustration on the freshly removed "H"-s, specifically, the inmovable screw. I made it to move, best not to mention how... let's just say that it involved rather direct physical violance. Once I managed a tiny quarter-turn, it rotated out incredibly easy and without any problem. What's more important: the remains of the carb appear to be still functional (I fully expected it to break in half or at least lose a couple of pieces). I think I'll replace the screw with a new one and re-install the "H"-s, and see if I can have them calibrated.
Still, if somebody knows the difference between the G and the H, that info is still welcome.
 

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Discussion Starter · #3 ·
The "H"s are back in the car. They were calibrated previously via the three movable screws and now, as I had four functioning screws, I managed to fine-tune them by the "What the hell, I'll turn this screw and see what happens!" method. (Actually I kept tabs on which one I turned and by what degree.) It's nowhere near perfect, but I think the car goes better. Not surprising, as the fourth screw had been tightened 100%. I think virtually anything is better than that. We'll have a go at a proper calibration, maybe I won't have to do a full rebuild.
Anyway, we JUST finished the job in time for an oldtimer show appearance. (No, the other cars in the background are NOT oldtimers :) Credit goes to the photographer. WARNING: Depressingly low Alfa-content! Some nice sets of wheels, though.)
 

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The G and H are both emission carbs so should be interchangeable. The best way to check is to remove the progression port plugs(the large brass screws just behind the idle mixture screw towers) and compare the progression holes. The nuts are to adjust the accelerator pump fuel delivery.

Sean
 
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