oh, i nearly forgot,
todays fiddling, in between other things went as little like this.
when i first drove the sprint, to stockport and back the first night, i was tremendously happy!
but after that, i felt that something had got wet, or was just starting to break down a bit,
it was just a bit, Grumbly! off the bottom and up to about 3500rpm, sometimes it would be less than perfect, so i started with the usual suspects, and changed the plugs, leads, diss'y cap and rotor arm to make sure it wasn't going to be a damp thing, and it wasn't, but at least they are all brand new now anyway.
a quick check of the air filter, proved nothing out the ordinary, so i thought i ought to delve a little deeper.
i routed through the cupboard and found my old timing strobe, and a quick check of the flywheel marks, and a fine tune, resulted in fractionally cleaner tickover, but still didn't repeat the drive to stockport, so deeper again,
i'm no stranger to carbs, admittedly i'm far more familar with something like mikuni flatside race carbs from the motorcycle game, but the principals are all the same, and my Weber IDF 40's looked pretty straight forward, so nothing ventured, nothing gained, and in i went.
a quick check over the set up, seemed to reveal nothing out of the ordinary, the linkage seemed good and free, and appears to pull on the carbs equally, so not a balance issue, so i removed and checked the jet set up.
mine turned out to have #50 idle jets, and #140 main jets, so i rang Tom at BLS to get his opinion on this.
as it turns out, the #50 idle jets are pretty much on the lean/weak side, and back in the day, Tom often swapped these out for #55's or #60's for a breathed on motor, so i promptly ordered a set of #55's from an old known weber/dellorto agent, and they promptly arrived today, so i just thought they're might be some folk who'd lke to see what goes on.
i'm going to assume that just about everybody with a carb'd boxer, has already unbolted the airbox to know what their car sounds like with exposed carburettors, but in brief, pull off the 2 breather pipes off the back of the airbox, release the hot and cold air intake tubes from the front, and then 2 x bolts and 4 x nuts will release the whole airbox and intake manifolds in one piece, so gently jiggle it upwards and off.
you'll be faced with this,
with the top gasket, just about cloaking the brass idle jets, and the tall brass emulsion tubes atop of the main jets, standing tall.
so gently lift the gasket off to reveal the idle jets fully, and you'll see them sitting flush.
i wanted to check further before just swapping out my idle jets, so first remove the idle and main jets by simply unscrewing with a well fitting screwdriver, then unscrewing the 4 x silver screws in this level of the carb, will allow you to get to the next stage below, the float chamber, and remove the manifold lug at the top centre to make the gasket removal easier, and you get down to pretty much the bowels of the carb, and look at all that sediment and dirt in the float chamber!
be careful removing this section of the carb, it has the float bowl and needle valve attached, which are delicate components, which will all come out very easily if you just take your time and make sure you're gentle, no worries.
a clean rag on the end of a rounded screwdriver, soon soaks up the fuel, and leaves you with the sediment to deal with, some of it is pretty stubborn, like staining, so a liberal spray of carb cleaner, rapidly loosens it, and then either rag it out again, or airline it away whilst covering the other vulnerable areas of the carb intakes, and it will soon look like this, a bit different eh?
re-install the float valve sections and gaskets, and then after another inspection and blow through, back in with the emulsion tubes and main jets, which are at the very bottom end of the brass tube, a little hexagon brass end, which simply pulls out, and as stated before, mine were #140's.
these only need to be seated with a gentle nip, no big daddy wrenching on the things, just because you can fit a shovel in the screw slot, don't!
time to swap the idle jets, which again just pull out of the brass corrector tube you've already taken out, so out with the #50's, and in with the #55's, and again a gentle nip just to seat the brasswork back home.
gently back on with the gasket, and simply reverse the intial strip down to rebuild the final airbox and manifolds sections.
one more thing i decided to do whilst i had the airbox off, was do away with the warm air diverter flap mechanism, which if you split your airbox down, and them prize the clips apart on the air intake side, you can chuck this little lot out straight away in my opinion.
a total waste of space if you ask me, and once done away with, i reassembled my airbox but used some convaluted hose as the cold air feed to the grill nozzle, and instead of the warm air feed pointing at the nearside cylinder head, that has now been trimmed and redirected to underneath the grill nozzle to double up the cold air feed,