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Author: Subject: Weber Help!
ttalps2000

posted on 27/6/19 at 08:27 PM Reply With Quote
Weber Help!

Currently having issues with syncing my 40 dcoe webers. I have the latest webcon under mounted linkage kit.

I have always had issues with one of the carbs wanting to flow more air at idle than the other. On my old linkages, i could independently adjust each carb and then set the idle, but cant do that with this. However this is not resolving my main cause of the issue.

I have taken the carb off this evening and there is a clear gap around the butterfly in the barrel. One side more than the other. There is no play in the shaft and does not bind etc, so assuming its not bent either. I rebuilt the carbs a few years back with new seals etc, but never removed the butterflys as they are a pig to do!

Main question is, should there be a gap around the butteryfly, or should they be sealing off all the way round?

They are older 40 DCOE italian Webers and do not have the air bleed on them.

I get one carb to settle nicely at 3.5 and the other is reading 5, the best i can get it to is 4.5!

All new seals and rubber washers set correctly too on the mountings.

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rusty nuts

posted on 27/6/19 at 08:53 PM Reply With Quote
You may be able to slacken the screws securing the butterfly to the shaft then adjust the position of the butterfly to centralise it which should take car of the problem unless the shaft has twisted ?
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ttalps2000

posted on 27/6/19 at 08:58 PM Reply With Quote
It appears to be central in the bore, but a gap all round. Looking at it again now, one bore seems to seal off nicely and the other needs a gentle nudge on the lever to get it to fully seat. May well be the return spring inside? However, seems to have plenty of tension and snap shut.

The screws cant be loosed and re-tightened as they are peened over and you have to file the back of the screw off before you can get them out or loosen them

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perksy

posted on 27/6/19 at 09:30 PM Reply With Quote
The Butterflys should close completely

Funny enough I've just had one of these in bits and rebuilt it for a mate
Both the butterflys weren't closing fully and it turned out that whoever had rebuilt it last had fitted the wrong (Too Weak) return spring and used a 6mm plain washer instead of the proper Weber Spring anchor plate


Check the return spring (Weber part Number 47605.027)

Double check for a bent/twisted shaft

Check the bearings/bushings at the end of the shaft (I've seen a couple that had been grit blasted without the carb being stripped fully and the crud was everywhere causing stiction in the shaft


Its not something daft like one of the nuts on the end of the spindle is too tight is it?

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ttalps2000

posted on 27/6/19 at 09:42 PM Reply With Quote
will look further tommorow night and report back!
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ttalps2000

posted on 29/6/19 at 12:32 PM Reply With Quote
Had a look at this again last night, checked the nuts, all fine. Spring is as it should be. Started looking more closely and the TPS was bottoming out on its movement, howerver it was only holding open the one side very slightly, which is the opposite side to the TPS mounting! Both appear to snap shut nicely now and TPS position adjusted.

Now to try it back on the car and see if it balances any better!

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perksy

posted on 29/6/19 at 08:41 PM Reply With Quote
It should now balance much better

Make sure the TPS is at the correct initial base setting for the map, Otherwise there'll be another problem

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ttalps2000

posted on 2/7/19 at 07:17 AM Reply With Quote
all hopefully resolved now. Also found the balance bar was fouling the other carb on the linkage and holding it open slightly too, so sorted that. All balanced out very easily apart from Cyl. 1 which has slightly higher air flow, but cant do anything about it really as they are older Webers and have no air correction screws on them. However runs much better. TPS all re-calibrated too.
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