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Discussion Starter #1 (Edited)
Awhile back when I had some work done on my 74 Spider , I asked the mechanic to lean out my Dellorto carbs (as they were running way too rich when I bought it)....he did, a bit later ,esp when cold , they seem to "spit"...often at low RPMs or cold I get this "Pfft, pfft" sound...I think it tells me they are too lean?...on a Dellorto how /where can I rich them up again? a picture would be great , and telling me how , which direction to turn if its a screw? would be great...I know NOTHING about Dellortos (or Webers , as I know they are pretty much the same)

did he lean them out a bit too much , or could the adjustment move by itself ? Or could it be something else, as it seems to get worse...(could it be because its getting colder outside?)

thanks in advance
 

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These are the mixture screws. Get a small notebook and take notes of whatever you adjustments you make, so you can go back to the original setting. Each "throat" has an adjustment for mixture and it can be richened or leaned by turning each screw in or out.

Turning them IN (clockwise) will lean the mixture.

Turning them OUT ( Counter Clock wise) will make the mixture more rich.



It's best to make a note of how many turns each screw is from fully seated (Turned in Clockwise). Turn in, as you count the turns until LIGHTLY seated and then return them to this original position as the base point. Make no more then a 1/2 turn adjustment at a time and then drive for a bit to see how she runs.

If there is no choke ( cold enrichment device) on the carbs, then the spitting and popping when cold can be quite normal. Don't sweat this if the engine runs sweet once warmed up.
 

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Discussion Starter #3
thanks...this makes sense....I will attempt it....guess I will start w 1/2 turn counter clockwise...,...drive it...thanks again!
 

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If you screw them gently clockwise until they hit the stops - but gently , don't force them then screw them all out 3 - 4 complete turns that will give you a sound base to work from - like jc says they do spit a bit from cold anyway and its really noticeable if you have a free flow filter , but shouldn't do it when hot - you need to turn the screws (one at a time) one way or other (half turn at a time) until the engine runs smooth with no stumbling at tickover
 

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Discussion Starter #6
I turned half turn left , (rich) but its obviously waaay to much...now it ran good while cold , but "blubbered" when warm almost stalled at idle , I had keep it going by giving gas...now screws are hot , and wont turn....waiting a bit w an ice cube on ea screw to turn back a 1/4 turn...or more ....
 

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Discussion Starter #7 (Edited)
ahhh shoot , now I feel really stupid...looked again , and I had turned the larger brass screw in front of the ones with arrows!! anyway....start over.
and now those wont turn back...they were hard to turn left , now wont turn right..they start to get bad...guss I need to take these to mechanic...get new screws if he can get them out...
 

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Discussion Starter #8
well, found out the screws I messed w first are cap screws...does affct it...but car still runs like crap , after running enough to warm up today it started running bad...must be a coincidence...
 

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Sounds like you unscrewed the progression cap screw - need to make sure they are put back properly so there aren't any air leaks - go back to basics and set the idle mixture screws to 3.5 turns out from stop - that should get it running reasonably well, then you can fine tune; Just be careful with those mixture screws in the tower - they are very fine thread and can easily be damaged - use a bit of WD40 on the threads
 

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Discussion Starter #10
lol, I did not unscrew them, moved then 1/2 turn , now stuck....but coincidentally when I test drove the car...something else happened....got oil on the spark plug up front....its also very sooty , the others are fine...guess its time to take engine apart....not by me , but by mechanic...at least I will have him look at it.
 

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Dude, I took the time to put arrows on the mixture screws and you messed with the wrong ones!!! :)

OK, you can take them out and put some oil on the threads and screw them back in. No worries as they are not an adjustment.

As a general warning, when working with brass screws get a screw driver that fits the slot perfectly or you will ruin the screw. Even if you have to go buy a new one and grind or file it slightly to fit perfectly. Don't ask how I know!!

I would get the screws back in properly and drive it to enjoy. If you have not messed with the mixture screws yet, don't. Work on getting it to run right again.
 

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Discussion Starter #12
Dude, I took the time to put arrows on the mixture screws and you messed with the wrong ones!!! :)

OK, you can take them out and put some oil on the threads and screw them back in. No worries as they are not an adjustment.

As a general warning, when working with brass screws get a screw driver that fits the slot perfectly or you will ruin the screw. Even if you have to go buy a new one and grind or file it slightly to fit perfectly. Don't ask how I know!!

I would get the screws back in properly and drive it to enjoy. If you have not messed with the mixture screws yet, don't. Work on getting it to run right again.
Yup, I know :oops:...
well, right now it seems like coincidentally something else went wrong yesterday...my buddy (who I called in Panama , retired mechanic) thinks the valve stem seals went bad on the front cylinder....I wont mess with it, will take to my mechanic....and yes , I did go out and bought a screwdriver that fit perfectly , still those brass screws wont budge....
next week I guess it will go in to the shop......hope to drive it soon again...:thumbup:
 
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