Weber Idle Adjustment Problem - Page 4 - Alfa Romeo Bulletin Board & Forums
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post #46 of 76 (permalink) Old 02-22-2019, 09:49 AM
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When you opened the progression holes, did you check all 4 butterflies at the same time? (That's where the twisted bar could come in etc.) At idle, assuming ~900-1000RPM, how many progression holes are uncovered?

Carefully check torque on your intake manifold. Did you personally install the intake manifold and gasket? If not, it may be time to pull the manifold and ensure there isn't any funny business going on back there. Check the vacuum port on Cyl #1 if your manifold has one.
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post #47 of 76 (permalink) Old 02-22-2019, 11:42 AM
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To remove any doubt I want to try to replace the carburetors with others I have at home, I'm dellorto but it does not change. If the engine is still and steady it will mean that the problem is in the weber carburetors and I will look for someone here in Italy that can rebuild them. Hoping to find a competent and honest person.
I proceeded to rebuild the engine in every single detail and I came to deduce thanks also your help that at 99% the problem is in the carburetors. We'll see if I was right, I'll keep you updated
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post #48 of 76 (permalink) Old 02-22-2019, 12:12 PM
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Hi Giacomo and all,

I do agree with you.
Just like you, I would also try to find the probem by elimination as I told before in post 9 but not like you mentioned in your post 47 by putting other carbs on the engine.
Using other carbs could give new uncertainties.
I would note down the grafic you found on your synchrone measuring device and than use the same carbs but change them from place. Check again with your (same) device and compare the grafics. This can help you to eliminate engine influences and maybe point you further in the right direction of the error: the carbs? I m aware that this is a serious job but that's the way I would approach the problem.

Salve,
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post #49 of 76 (permalink) Old 02-22-2019, 12:31 PM
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the carburetors I bought them used and at the time I just cleaned them to replace all the gaskets and to cook everything I could check by looking at the manual in my possession. There were no anomalies. Rereading the whole discussion I found those who solved or almost. I do not really know the condition of my carburetor having bought it used, it could be that who sold it to me had the same problem as me.
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post #50 of 76 (permalink) Old 02-23-2019, 02:35 PM
I like the idea of swapping carbs. I've done that before and concluded that indeed the carbs had something wrong that was beyond my skill set to detect.

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post #51 of 76 (permalink) Old 02-23-2019, 04:10 PM
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This happens. I restored nice a pair for Fred S, some years ago, and one ran funny for him, front or rear position, it did not matter, it was bad. I had him return it, went through it completely once again, found nothing, and nothing wrong. He tried it again and it was 100%. Totally clueless as to what I "fixed".
It happens. Possibly it just wanted to travel across the USA... twice.


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post #52 of 76 (permalink) Old 02-25-2019, 01:11 PM
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I no longer have the carburetors I thought I had available. So as suggested I told myself that the test of exchanging the carburetors was right. Having the carburetors in hand to remove the pin I said to myself, so as not to go deeper. So I also removed the bearings and I saw that the leather or rubber seal, I can not figure out what it is made of, it's all worn out and then maybe it blew air. I will take sealed FAG 607rs bearings and new mixing screws. we'll see.
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post #53 of 76 (permalink) Old 02-25-2019, 03:41 PM
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The original seals are made of leather, you'll be much better off with the sealed roller bearings, but make sure that the throttle shaft is not worn where it passes through the bearing, as it will still drag air in. The bearings should be a tight fit on the shafts. If not you'll need to fit new shafts too.

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post #54 of 76 (permalink) Old 02-26-2019, 04:08 AM
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this is the situation I found. You can clearly see the worn shaft in the middle and the leather that makes the seal very worn, the bearing is very noisy.

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post #55 of 76 (permalink) Old 02-26-2019, 08:20 AM
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That is normal, and not necessarily wear unless you can feel a "lip" at the edge of the area where the blue is worn off. The shine is caused by the center bushings as the bar itself is pulled against spring pressure from the offset of the accelerator pump cam. The shine at the right end of your picture is possibly from a bend or twist in the bar caused by damage from incorrect removal / installation, or incorrectly set butterfly plates. The bar should be checked for both straight and twist before reinstallation.
Below is a steel bar set up in my lathe for straightening. One of the pair had 2 bow type bends, the other one and a twist. Both bars showed evidence of being drifted out with a punch (incorrect) instead of being pulled with the correct Weber slide hammer. Generally the bars and plates should not be removed without good reason. Reset of worn in plates can be time consuming or impossible due to wear.
I spend much of my Weber restoration time often correcting issues caused by well intentioned DIY rebuilders that only lack experience. Restoration of good Italian Webers should be done with care. Below is a pair of 45DCOE14's from a 1966 GTA recently completed.
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post #56 of 76 (permalink) Old 02-26-2019, 08:43 AM
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Gordon I highly esteem you and I read between the lines what you want to say. I took great care to remove the post and I did it because I realized that the leather gaskets are damaged. I will replace the bearings with these.




Another thing that influences I believe is this type of mixing screw. According to your experience is correct for a 40 DCOE 32?

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post #57 of 76 (permalink) Old 02-26-2019, 09:58 AM
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The mix screw can be one of 2, maybe 3 depending on WHEN your 32's were made. If they have a "lot number" on the top in place of the serial number, a number like "3S or 2B or whatever", the fine needle might be correct. Generally those were used on emission and some early pre-emission Webers. Most 32's used the blunt needles pictured on the left in the photo below. The longer taper needles will work as well, but the fine needles have a smaller port and different seat.
On the Webers designed for the non-sealed bearings, you will discover that those work best, but must be cleaned and repacked with waterproof grease and a new oil soaked leather seal after years of service when the leather shrinks or dries out. The sealed bearings are used on later Webers including the New Spanish Webers that use green (Viton) oil seals in the body cavity behind the bearings. These seals often require replacement when this type Weber is serviced. Not a simple job as everything must be removed and re-set, unlike those with non sealed bearings.
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post #58 of 76 (permalink) Old 02-26-2019, 10:13 AM
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also according to me the right ones is the second from the left. These are the lids of my carburetors
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post #59 of 76 (permalink) Old 02-26-2019, 10:48 AM
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WoW! Those are interesting, they have a combination serial number with a mould number! NOT emission type.
My guess would be the second type needle as well. The fine needles might seat on the needle shoulder, rather than the point taper. Remember, NEVER use force screwing these in as the seat can easily be damaged. You might install initially without the spring to feel how they seat while looking for the needle tip in the tiny hole in the throttle bore.
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post #60 of 76 (permalink) Old 03-04-2019, 02:57 PM
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waiting for the long mixing screws that I ordered to arrive, I mounted the carburetors after having only replaced the bearings. This is the result

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