thetankwad
|
| posted on 13/6/04 at 09:51 AM |
|
|
twin dellorto dhla help?
had a headache yesterday. tried to set up 2 dellorto dhla's on a lancia 4 pot twin cam (Beta engine). Can anyone shed light?
Car ran as a bag of poo already, misfiring, spitting all through the revs and never exceeding 4krpm. checked the plugs, and cyl 1 and 2 were spot on,
3 and 4 were sooted up. decided to record mixture settings and start from scratch. Odd thing was, carb for 1 and 2 was at a high fuelling setting (6
turns open), 3 and 4 was barely open (hardly 1 turn)!
Gave all 2 and 1/2 turns from closed and fired it up. Poor idle not remedied by idle adjuster, still misfiring. Carb for 1 and 2 leaking fuel out
intake and making an offbeat sucking. Airflow meter recording 3ish. Carb for 3 and 4 not drawing air. However, no matter how much i adjusted it, i
could not get it to rev smoothly or idle. I had to forgive the idle on part to it having 2 piper magnum 289 cams. Have stuck original settings on as
they allow the car to vaguely run. The car ain't mine, and i was doing a favour, so i stopped short of my usual "right, surgery
time!" approach. Can anyone shed light??
--Lets get down to Business!--
|
|
|
|
|
Peteff
|
| posted on 13/6/04 at 06:01 PM |
|
|
Is it definitely the carbs?
Is the timing alright, any special settings with the cams?
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
|
|
|
thetankwad
|
| posted on 13/6/04 at 06:14 PM |
|
|
I'd say so. The car suddenly fell out of tune with no warning. Electrics have recently been overhauled, and i checked points etc. too.
--Lets get down to Business!--
|
|
|
britishtrident
|
| posted on 13/6/04 at 06:19 PM |
|
|
Start by checking the firing order, if points ignition check the points gap on each lobe of the cam and the the mechanical advance isn't stuck,
clean the plugs, have a quick look at the cam belt and valve timing before moving on to the carbs.
Check the cold start mecahanism isnt stuck open in one carb and the mountings and "O" rings are ok .
***Check one carb isn't flooding *** and the jets are tightly screwed in place***., if none of the above clean the jets and check for
water/dirt in float chambers and check float levels.
Only then try synching the throttles by the time honoured method of using a tube held to eack intake -- must be held at exactly the same spot for
each intake trumpet. -- listen carefully to the the sound any popping can indicate vavle problems.
If none of the above do a compression test.
[Edited on 13/6/04 by britishtrident]
Just to expand a little I have always found with suspected carb problems start with the simple things first --- also with this style of carb
system with one throttle per cylinder the stethoscope method od balancng carbs is much more informative than than using an airflow meter -- but it
takes skill getting the end of the stethoscope tube held at the same "sweet spot" for each carb.
With DCOEs a DHLAs don't start by twiddling with the mixture screws that is the last step -- check everything else first.
I once had similar symptoms only on cylinders 3 & 4 tuned out to be a snapped camshft.
[Edited on 13/6/04 by britishtrident]
|
|
|
