View single post by Koit
 Posted: 11-27-2015 07:10 pm
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Joined: 11-27-2015
Posts: 3

I'm new for this forum, but I registrated for a reason, namely I purchased an old volvo 164 and it has been converted from bosh mechanical injection to carburettors, three Dellorto DHLA 45 C's.
So its a B30 engine strait 6 with displacement of 2978 cc, with quite high compression ratio of 10:1. Because the car didn't run great at all and the carburettors were really dirty on the outside the first thing I did was cleaned up the carburettors.

 The insides

So it had:
Choke: 36
Aux. Venturi: 8011.1
Main Jet: 150
Emulsion Tube: 7772.7
Air corrector: 160
Idle jet holder: 7850.9
Idle Jet: 60
Cold start  emulsion tube: 7482.3
Cold start jet: 95
Pump Jet:40

So I read the SpeedPro series booklet How to build and powertune weber and dellorto carburettors and it gave some suggestions on what the parts should be for particular dispacement, I belive my engine is rather stock. So for the reference some parts are off.

Idle jet 50 or 55 with emulsion tube 7850.6
Emulsion tube 7772.4 with air corrector 180
One smaller aux. venturi 8011.2

So after the clean in ultrasound bath, carb cleaner and compressed air it seems I have more less got the engine to idle, but it's still bit rough. Slow acceleration works good and from over 2500 rpm it runs good. The problem is quick acceleration completely fails the engine chokes and looses rpm and wants to die out. So there's something fishy with the jet pumps I assume but its my first contact with dellorto carburettors and I saw this forum seems to have lot of knowledgeable users in theese matters.
The previous owner said that when he was driving the car it didn't have symptoms like this. I have checked the jetpump holes are clean however I haven't jet tied if they squirt when taken of the engine.
I checked the timing on the engine with strobe and it seems to be 10 degrees BTDC as it should on 1000rpm.
One other question, it seems theese carbs don't have air bypass valves for balancing, so how should I balance them?

I haven't measured the exhaust yet with wideband lambda but It seems the mixture is a bit rich, the spark blugs where carbon fouled. So what do you guys think?