how much movement on webers

[jonsharland]

When I got my carbs tuned the guy at redline (in slough) told me that my carbs had been attached too tightly

I have 8v vx classic -

my carbs don't move at all and have been tightned so that the rubber gromets are hidden. is this correct or should there be some movement on the webers /

 

 

thanks

Jon

 

**is that an old Morgan **

[Silver 21]

Jon

 

There should be movement at the 'thackery' washers and you should be able to see some of the grommet. I don't have books to hand but I remember there is a measured movement figure at the end of the intake trumpets, I think it is 1/4". ie hold the carbs, move them up and down and there should be movement of said amount in a vertical direction.

 

I am sure someone will post the correct figure shortly

 

 

 

Graham

 

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[Graham Sewell]

Out of curiosity, who tightened them up in the first place? If you bought the car as a factory built car, I would be asking them for compensation for cost of the rolling road as I presume this is why you were getting your earlier problems.

 

Cheers,

 

Graham

 

Low tech luddite - xflow and proud!

[jonsharland]

This is not why I had the previous problem the previous problem was caused by my father and I trying to tune the carbs ourselves

but it was one thing that the guy pointed out as wrong - they were put on by the factory

 

Jon

 

**is that an old Morgan **

[Phil]

I had the same problem unfortunately caused by my lack of experience with carbs, they were loose and I thought this to be wrong and made the mistake of tightening them, result realy bad running and tickover all over the place.

I purchased new washers and alloy plates from redline who were the most helpfull but upon inspection I wish I had not purchased new alloy spacers/gaskets as these were ok and very expensive, nut I did need the 'O' rings and washers etc.

Redline advised me that there should only be between 5 to 10mm movement measured at the end of the trumpets [standard trumpets] and the best way to achieve this is by having the thread just showing, virtualy flush with the top of the lock nuts provided.

The job was easy but fiddley and very much worth while.

 

Try www.se7en-up.co.uk as they have a down load for webber carbs and this gives you all you need to know to tune the carbs yourself.

 

 

[gramey]

Thackeray washers (these are the coil spring looking bits) should be compressed until you get .035"-.050" gap between the coils.

The rubber soft mounts with the 1 or 2 metal cup washers (some people only use 1 on the nut side) should be compressed to .280" (7mm) from its original .380" (9.5mm). This dimension is for the rubber only, not including the cup washer(s). Many people put Thackerays on the bottom where fuel dribbles can't dissolve them and the rubber/cup washers on the top. The source of this information is Weber themselves.

George

[Roger King]

Thackery washers are those double spring washer things and were superceded even before I started building engines - the reason? In the last 25 years I have NEVER seen a set of carbs mounted with Thackeries where at least one of the Thackeries hadn't broken.

 

The rubber grommets are far superior, but unfortunately, any guidance about the amount to compress them or about the gap to leave between the steel cups is invalidated by the facts that different batches of the rubbers are different thicknesses and that the flange depth on the steel cups varies so much.

 

The purpose of flexible mounting is to reduce vibration and thereby stop the fuel frothing in the float chambers.

 

Ideally, the carbs should be mounted as flexibly as possible without having air leaks around the 'O' rings. In practice, a vertical movement of 5 - 10 mm at the air filter is about right without forcing anything. Sadly, everyone has a different definition of 'forcing', so in the end it comes down to experience.

[captain chaos]

IMHO the Thackery spring washers are useless. Atleast one of the set would break on my carbs within a matter of weeks and are really fiddly to replace. I went over to the rubber grommets and have not looked back.

[Geoff W]

I also have an 8V Vx Classic and have recently been down the same route, having suffered from rough running at low engine revs and poor pick-up. Engine was bored out to 1800 by Caterham and after about a year I could not get engine to run right. Eventually went to Arrowstar (I was green at the time!!) they put it on a rolling road and changed all the jets in the carbs. It ran superbly after this until recently when it went off tune so badly I invested in a syncrometer to balance the carbs. This was successful but lasted one journey to Stoneleigh. Having tried unsuccessfully to re-tune them I talked to a guy in my local area and he put me onto John at CES Power in Buckingham. John is brilliant; he suspected it was not the carbs and gave me along list of things to check, the main one being air leaks on the manifold. I have now changed the inlet manifold gasket and replaced the 'O' rings between manifold and carbs and adjusted the rubber grommets to the figure shown in the Caterhan Manual "The correct gap between the captive washers should be between 0.015" and 0.025" (0.38mm & 0.64mm)". Having done this I now realise that they were far too loose before as I remember there being a much larger gap between the washers. The engine now runs a whole lot better and I can only assume that there was air leaking in between the 'O' rings (the gasket loooked completely sound) as the carbs moved excessively due to engine/car movement. Who's a happy boy then? teeth.gif teeth.gif

 

H7 CAT