[TR] Strombergs running rich

[DAVID MASSEY]

Another non-obvious problem could be the top of the float bowl has no vent.  In this case a bubble of air can be trapped in there and not allow the fuel level to rise and shut off fuel.  The late model TR6 carbs had a small valve that switches this vent from the port on the face of the carburettor and a special port that connects to the charcoal canister.  If the air filter gasket doesn't have a hole lined up with that port the air can't vent out.  Also, the special port, which is active only during closed throttle is part of the Anti-Run-On system.  If that has been stripped out all bets are off as to what happened to the special port.  

Make sure the holes in the A-F gasket match the holes in the carb face and make sure that extra port is not capped off.

Dave 


 

    On Tuesday, October 3, 2023 at 05:38:09 PM CDT, Anthony Rhodes <spamiam at comcast.net> wrote:  
 
 If it is dumping gas that badly, then it is not a problem with the metering needle.  That is really a fine tuning device.

That much gas may be from the float chambers having too much fuel.  Way too much.  

Check the pressure in the fuel line.  If it is too high it will overcome the float valve.  

Maybe the float valves are not sealing?  Maybe the floats are not adjusted properly?  Or not actually floating and are just sinkers?

-Tony

Sent from my 1837 Babbage Analytical Engine

> On Oct 3, 2023, at 2:44 PM, triumphs-request at autox.team.net wrote:
> 
> Message: 1
> Date: Thu, 28 Sep 2023 17:57:54 -0700
> From: Frank Burkhart


>  I?m hoping that someone out in Triumph world can provide some clarification on carburetors.  Currently, Zenith Stromberg carbs on my 1975 TR6.  The car has been running poorly since Trimphest (too many RPMs?).  And then it died completely but turned out to need a new rotor.  Asked the mechanic, Mike, to take a look at the everything to figure out what can be made better.  What he found was the carbs were dumping gas into the cylinders especially when starting, to the point the gas was washing down the cylinder walls preventing the rings from sealing.  Result was a lot of white smoke.
> 
> The carbs were rebuilt about 18 months ago by Apple Hydraulics in New York.  Supposedly all new parts including a new piston in one of the carbs.  Mechanic Mike is questioning the quality but . . .  Several paths to try:
> 
> 1.  New needles and basic over haul.  Least expensive but maybe stopgap measure.
> 
> 2.  Rebuild these carbs using a different shop.  Mike recommends a shop in Colorado. I?m would worry about a 2nd rebuild in short period of time.
> 
> 3.  Replace the carbs.
> 3a.  Mike has a pair of SU carbs in good shape.  Mike would replace ?consumables? and install
> 
> 3b.  Find a pair Stromberg carbs
> 
> 3c.  Mike likes carbs by Mikuni
> 
> 3c.  Replace with Webers
> 
> Any ideas / suggestions on what path seems the best?
> 
> Hope all the world is going well for all.  Hope to see everyone at Velocity.
> 
> 
> Thank you,
> Frank Burkhart

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