Carb problems

OnTheRoadAgain

OnTheRoadAgain

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So the good news - after sitting in the garage (keeping warm) since mid December, Arthur passed him MOT last week - a small challenge of a new clutch master and slave... but the test was passed with no advisories...

Yet the bad news - he's still there... Apparently, I'm told (and agree) "he's running like a dog"...

Fortunate news - Leighton Buzzard (home) is the home of carb repairs - Carburettor Exchange... So I have the SU carb, but a big flat spot from about 1000-2500 revs... and worse since I swapped one manifold top with a replacement (CommerTim) one.

Garage are going to give to Carburettor Exchange - any advice... change of needle size?? it's a 1.5l Rootes engine so I don't think it's the choice of carb...

Discuss...
 
Best bet is to get the needle specifically tuned to the engine on a dyno to remove fuelling flat spots. Had mine done and made a world of difference
 
Putting heavier oil in the dash pot sometimes does the trick. I had a similar issue with the Mini, bit of a flat spot, and using some Valvoline 20/50 instead of Comma 20/50 cured it. The Valvoline seems a lot thicker than the Comma stuff which seems odd as it's supposed to be the same grade. I use EP90 gear oil in Harvey, but as gear oils use a different grading system it's not that much thicker than a decent 20/50 when cold - but it does the trick.
 
It's worth a try.
If the dash pot oil is too thin then the piston will rise too quickly and can cause a weak mixture. Because this is a custom installation it needs a bit of trial and error to get it right.
 
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