Weber set up

[DCollis]

Hi

I have a 1994 with a 1600 CVH engine and twin 40 dcoes. They car has been laid up for several years. I have flushed the tank and fuel lines , cleaned the carbs, new leads, plugs and distributor cap. 

The car miss fires under load. 

Can anyone recommend a tuning garage not too far from Warrington Cheshire?

Thanks

[Lyonspride]

Change the misab plates and maybe the inlet manifold gasket.

The smallest of vacuum leaks at the misab plates will have you running around in circles spending silly money at garages and tuners. With a car that age, the rubber on those plates will almost certainly be unable to handle modern fuel (with ethanol) and will perish unless replaced with new.

Misfire under load, worsens when hot?

[ken 16]

were our the misab plates located

[Dave Eastwood (Gadgetman) - Club Chairman]

They’re the metal plates with the donut like rubber seal in the middle, that sit between each barrel of the carburettor and the inlet manilfold,

They seal the joint, yet allow the carb some movement - Weber’s should not be mounted rigidly on the manifold, or vibration from the engine can make the fuel in the float chambers froth.

[Wilfman]

47 minutes ago, Dave Eastwood (Gadgetman) - Club Secretary said:

They’re the metal plates with the donut like rubber seal in the middle, that sit between each barrel of the carburettor and the inlet manilfold,

They seal the joint, yet allow the carb some movement - Weber’s should be mounted rigidly on the manifold, or vibration from the engine can make the fuel in the float chambers froth.

I think Dave should have said NOT BE MOUNTED RIGIDLY...... Webers need to flex slightly to the manifold

[Dave Eastwood (Gadgetman) - Club Chairman]

Oops, don't know where the NOT disappeared to, hopefully the rest of the sentence made it clear though!

[SootySport]

Might be a good idea to strip down the carbs  and give them a thorough clean, then rebuild with a service kit from Eurocarbs.

[Lyonspride]

6 hours ago, SootySport said:

Might be a good idea to strip down the carbs  and give them a thorough clean, then rebuild with a service kit from Eurocarbs.

 

When I rebuilt and reconditioned mine, I found parts that had been badly modified, parts missing and incorrect parts. People used to do some pretty dumb things to weber carbs back in the day.

[DCollis]

I have done all the things suggested. Refurb carbs, new leads, new distributor cap, new plugs, new gaskets, new misanthrope plates. 

Drained tank and all new fuel.

I have bolted the carbs solid to ensure no vacuum leak but it still misfires under heavy load.( Tempoary).

I am convinced the carbs need tuning but I cannot find anybody. There must be someone not too far from me in Warrington????

[Dave Eastwood (Gadgetman) - Club Chairman]

The carbs shouldn’t be solid, they need to move on the manifold slightly, or the fuel in the float chambers froths with engine vibration, and most likely will cause a miss fire,

[Lyonspride]

On 4/8/2018 at 19:03, DCollis said:

s solid to ensure no vacuum leak but it still misfires under heavy load.( Tempoary).

I am convinced the carbs need tuning but I cannot find anybody. There must be someone not too far from me in Warrington????

 

So here's the thing, if the carbs once ran fine, then they've already been jetted and hence have no real tuning to do aside from the idle mixture screws.

The float heights could be off (low float levels cause an array of issues) and are set by bending the arms, the old brass floats can sometimes develop holes that causes them to fill with fuel. The float valve might be worn/sticking (usually noted with fuel pouring out all over the place).

 

 

 

[Oliver1]

Could poor synchronisation be the cause?

[toys4x4boys]

AB Garage, Chester

Few of us taking kits, well 20 actually on Saturday for a rolling road day.

Proper old school, knows carbs, and drivable even roughly form Warrington.

Address: Unit 167B Castle Close/Manor Lane, Deeside CH5 3QX

Phone: 01244 537701

[Grizzlee]

Drop me a PM with your number, I'm in Warrington and would be happy to take  a look for you.

Graham

[Davemk1]

If the miss is happening under heavy load (wide open throttle - WOT) then the likelihood that it's a air leak around the mounts is very low. Under WOT there is so much air moving through the venturis, and the vacuum is so low, that a very small amount of air coming in around the soft mounts will have little to no effect. Leaking around the soft mounts will typically show up in a big way at idle or while cruising but no so much under WOT.

If the issue only happens during extended WOT the float adjustment could be an issue as the fuel level can drop in the float bowl which can cause the mixture to lean out and miss.

If they idle fine and work well while cruising but miss during WOT I'd be looking not at the carbs but at the ignition. A bad coil can work OK at lower rpm's but can't keep up with the needed recharge rate at higher rpms.

If you haven't already you should pull the plugs and make sure that they aren't fouling from over-fueling. Your accelerator pump jets could be too large and be throwing too much fuel in during roll-on to WOT and making it run rich and/or fouling the plugs. A quick read of the plugs should tell you.

I hope that helps.

dave