Need help with Dellorto 40 set up on new 1776

[[email protected]]

Idling at 4 I'd say you have too much idle timing. I like to get the snail to read 5.5-7.

It gets more stable when you get more air into it.
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[modok]

maybe the throttles aren't centered?
I guess if it runs fine who cars

[mightymouse]

hmmm. ill have to look again. I think i may be at 10 btdc at idle. Kindof a weak 009. it only adds 18 degrees of timing.
So i just shoot for 28 total and go from there. 2700 altitude and THIN ass air. or id go 26 timing and leaner.

DAMNIT!!!! i need to order an SVDA. john.... you havin any specials soon? just spent 1500 on the bus and im down right now. need to get caught back up to toss cash at an SVDA.
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Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson


Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters.

[wbrown45]

You are going to need smaller venturis for your setup to work. I ran 30 mm venturis on my 40 DRLA's which were on my 40 x 35.5 mm heads. When I went to 39 x 32mm 041's I went to 28mm venturis to get my low RPM power back. We set up many engines with these same 28-30 mm venturis at Karl's Custom back in the day. They all seemed to like the smaller venturis which kept the air speed velocity (laden, or unladen? ) going strong.
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OK Thang

[pat griffith]

Ok today I looked at my floats again. There was about a 1/2 inch of gas left in both bowls after 3 days. Readjusted one side a little bit. Both are at 6 And 13 mm. I still have a small drip on one barrel but much better but not perfect yet. To me the throttles look centered. I have checked for a vacuum leak with both carb cleaner and propane and don't get any increase in RPM. I gave a quick shot of carb cleaner down the stacks one at a time and had no increase in rpm so I am going to say that my idle circurit are not blocked. At 1500 rpm I get no popping out of the exhaust. The one carburator that has uneven readings from the barrels is still the problem. I can turn both air mixture screws all the way in at the same time and it dosen't effect the engine. If I do that on the other carbuator I will stall the engine. I am really puzzled at this point. What do I do now? Guess that that carb has a problem. Vacuum leak , twisted throttle? I dont know. The engine in new. All of the spark plugs look ok. I guess I could do a compressiom test and leak down test of the cylinders but I doubt that that is the problem. Any more ideas?

[the2ndcashboy]

You don't have the plug wires on those two cylinders swapped do you?

It's fairly easy to check for a twisted throttle shaft. Just pull the carb off and check the gap between the blades and barrels with feeler gauges (where the gap is supposed to be I mean, at the progression ports). If the shaft is twisted the gap will be larger on one than the other.
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[mharney]

What you want for throttle plate alignment is that the two plates are staging the progression holes at the same time and that the flow readings are the same through the range.

Gotta stop the dripping.. its messing up your ability to adjust them.

[pat griffith]

The drip is just occational now. Once every minute so. Fuel pressure is set at 3.5 psi How do I make it stop? Do I need to increase or decrease the float level? I think I understand what you are saying about the progression. I did notice something the last time I had this carb off. I noticed that at the idle position the front barrel was slightly different.The throttle plate was just about spliting a small hole in the barrel wall. The back throttle plate was just covering this hole. Very close but none the less they were different. I didn't have the chance to see if the other carb was set up like this. I will double checK the wires. I don't think this a the case as the engine runs strong past idle.

[the2ndcashboy]

I've heard that vibrations in the hex bar linkage can cause the accel pumps to dribble. Does it dribble with the linkage disconnected?
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[MoPor]

[pat griffith]

So are you saying that both holes should be showing? If so buy how much?

[mightymouse]

Whats the snail reading on each hole? what rpm is it idling at? where is the base ignition timing?
_________________
Nothing can stop the man with the right mental attitude from achieving his goal; nothing on earth can help the man with the wrong mental attitude.
Thomas Jefferson


Note to EVERYONE.
Know your ZDDP levels or you WILL lose a cam and lifters.

[pat griffith]

On the good carb the reading is 7 on both barrels. On the other carb the front barrel is 7 and the rear is about 3. Nothing I do seems to change that. I think that the idle is around 850 and the advance is around 10 . I cant be positive on the last number . Will check again and report back.

[mharney]

What I am saying is that both plates should reveal the holes at the same time. If they are not the same, i.e., one plate revealing a progression hole before the other one does, the throttle shaft is twisted. And yours is. You need to have it repaired.

[Alstrup]

Pull those carb off and send them to Mark or ACE for check and repair. something is really screwed in that set.
- I still say that if a 6 mm needle stop is nessessary, more than one problem most likely occurs. They can normally hold back to about 3 mm float height. Like i wrote before, 4 max 5 mm is the sweet spot as to my experience and per Dellorto´s own tech book for Alfa Romeo´s.

T

[[email protected]]

first thing to do is remove the linkage, and switch carbs from side to side. Does the low snail reading follow the carb, or not? If not something is mechanically wrong with the engine, and the carb work is not going to fix that.

Know what the problem is before you spend a lot of $ fixing it.
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[pat griffith]

Yes I did switch sides and the problem followed it.

[garabaldy]

So Pat I'm having the same problem, did you figure out what the solution was?
thanks

[PumaGTe]

I have a question about Dells as well.
What is the basic starting point for the mixture screws? I read 4 turns out?

Allthough I hate to see people have problems with there cars, this kind of threads really teaches me a lot.

[Brit01]