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I generally agree with the above posts - to a limit. The normal idle jets for these carbs on a 2L Alfa engine are 50F8. I like to run a little lean and I prefer 50F11. But if he has these jets and he still has the problem and it is alleviated by screwing out the idle jets, then I say he has either an air leak or low float level. I don't agree that putting in bigger idle jets is the solution. It may mask the symptoms but not cure the problem. Say he has an air leak and he makes his engine run better by installing 55F8's. Then the leak gets bigger. What should he then do, install 55F9's?
 

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I generally agree with the above posts - to a limit. The normal idle jets for these carbs on a 2L Alfa engine are 50F8. I like to run a little lean and I prefer 50F11. But if he has these jets and he still has the problem and it is alleviated by screwing out the idle jets, then I say he has either an air leak or low float level. I don't agree that putting in bigger idle jets is the solution. It may mask the symptoms but not cure the problem. Say he has an air leak and he makes his engine run better by installing 55F8's. Then the leak gets bigger. What should he then do, install 55F9's?
I agree if he has normal range 2L jets and has to run the idle air screws out 4 turns (or 8 flats) then he has other problems. I believe I would check the jets and the fuel level first. the idle screws out and a huge flat spot reads like the jets are too small--but you never know until you look
 

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Discussion Starter · #23 ·
Thanks, guys. I had an opportunity to look at the carbs again this morning. The idle jets are 50F8. The idle mixture needles were visually inspected and are okay. I sprayed some carb cleaner around the base of the carbs and the adapter plates and got no acceleration. I am out 4 turns in this video.


I guess the next thing to check is my float levels?
 

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hi again Espresso Veloce Tim.

I did start by writing about my opinion and others opinions but deleted it.
I prefer to start with the easy way,by richening the idle circuit,then evaluating from there.
I promice not to add any more to this topic.
Good luck.

Robert
 

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Discussion Starter · #26 ·
The weather has been a little sketchy around here of late, and I have been busy with work, but I wanted to give an update. I made a tool for checking the float levels, and they were low. I must have been measuring incorrectly when I rebuilt the carbs. The floats now sit at 6.5mm as measured with a 6.5mm rod. They are a little more than 15mm in the other direction, but it seems that shouldn't matter as much. I didn't want to completely disassemble the carb covers to bend the tabs.

The result is that I'm not getting any of the spitting now, but my idle screws are still out around 4 turns. There are no air leaks that I can discern. The engine seems to be running great, but I am only getting around 19.5 mpg in mixed conditions driving. Idle jets are 50f8.

Would there be sense at this point in following Robert's advice and going to the next larger jet? What are the trade-offs there, other than still not knowing why my idle screws are turned out so far. Fuel pressure is good and regulated. Timing perhaps? My timing marks are for Spica. I have a timing light, but is there a better way to set this?
 

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Next size up is 50F9 or 55F8. You have nothing to lose beyond the cost of the jets. These will make your fuel consumption worse. 19.5 mpg with SPICA cams and classic Webers is not too bad. I get 23-24 but I have emissions Webers, 10:1 pistons and big sparks which all help.
 

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Im still here.

I would not follow Roberts advice if all is good now= no spitting.
But usually,idle mixture screws wound out more than 3 turns GENERALLY means that the idle jet is too small.
If you feel it is running lean between idle and 3000 rpm,and at cruising,you know what to try.
If its all good now= leave it alone.
Sorry about my previous comment,but I usually start with the easy things first,and then look for the problems.
Here in Australia,for some reason,I am putting in bigger idle jets and it USUALLY fixes the problems.= spitting
Remember,,all tuning is done at engine operating temperatures first.
Then play with idle circuits
Cars require a richer mixture when starting,like using the choke.
By all means= check tappet clearances and cam timing,and compressions and point gap and timing,etc,but the start of this thread said = everything was good before.

Robert
 

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Discussion Starter · #29 ·
Robert, All opinions are welcome around here, and sometimes even the most adamant authorities can be wrong on some point. :) I was going to take the car for a drive down to Nashville this week, but it looks like the weather won't be cooperative. Round trip is around 350 miles--that would be an interesting test for the car.

I think it will be worth trying to swap out jets, but I think I'll look at timing again, first. I did think I was getting better mileage previously.

In any case, the car is improved, and so far, this is the best its run in at least a decade.
 

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Advance curves make a difference. I have posted about my experiences with the different programmable curves in the 123ignition distributor. It is easy to search and find.
 

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Discussion Starter · #31 ·
I read the posts about your experiences, Ed, thanks! It's great info. I'm not ready to move up to an electronic distributor--the new business isn't making enough money to pay the regular bills yet, so I can't really justify Alfa upgrades right now. But next year...

We did pull the distributor and make sure it was functioning properly. The only concern I have is that the timing was set using the Spica marks, and I haven't been able to find anything that says "when you go from Spica to Webers, this is how you set the timing differently".
 

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I always set the max advance with a strobe. There are differences of opinion about what the max advance should be. My experience is that about 38 degrees is right but some people think that it should be around 34.
 

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I use P which is TDC. I verify that the pointer is in the correct position with a DTI in the #1 plug hole. I then use a variable delay strobe. Alternatively, measure the diameter of the pulley. The circumference is pi*D. The distance from P to your new M is the circumference multiplied by max advance angle and divided by 360.
 

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Ed, how do you tell how many degrees you're at when the timing marks are M P F?
A page from centerline (I don' think Joe will mind) showing how you engine came timed from the factory. http://www.centerlinealfa.com/tips/images/p51.pdf

Another page with cam timing templates to see what your cam bearing marks are from the factory and how to re-mark them where you want. (102-102?)
http://www.centerlinealfa.com/tips/images/installation/cam_install.pdf

When the cams are set correctly, use a timing light and set the pointer to M on the flywheel or a little under by adjusting the distributor (after loosening) at 4~5k rpm . There are many variations but this will get you in a nice manicured ballpark.

A dial back timing light will read off in degrees from tdc if you need to know exactly how many degrees you are from tdc
 
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