thanks guys - will look to get the OEM air filter assembly cleaned up & fitted - lets hope its all there. Are parts available for this - I took a quick look yesterday & it looks like there is an oval cannister, which is a bit rusty & also the elbows have the usual perishing. can anyone find a clear diagram to show me exactly what parts are required & where they go - as I never took this off, I am not sure what goes where. thanks Also, can people give me an idea of what sort of speed that take their buses to in each gear for this set up, i.e. 1700 type 4 with the standard (CK code?) gearbox, just to get an idea of if I am giving it enough beans (i don;t tend to be much of a 'revver').
Changed the plugs today, and they all look a little white - I understand that this means the bus is running lean. they look like this - hopefully you can see in the photos.. Can I adjust the mixture myself easily? Not really clued up on carbs, but is it just a case of richening up the mixture by turning the fuel mixture screw? If so, can anyone give me an idiots guide of how I do this. I realise that my bus probably needs to go on a rolling road to be set up properly, but would rather get it a bit closer to how the mixture should be myslef in the meantime & see how that goes - does run fine when cold (due, I assume, to the fact that the choke is richening up the mixture,) but when warmed up, the choke is off, the bus is running too lean & it is then down on power. thanks.
Your plugs show the annoying comination of hot and soot. So dirt in carbuettor passages or a split hose may make for lean running at some RPM and rich at others. As well as a rolling road, consider following the procedures in the Bentley manual, and /or come to Techenders and people will hover round you and help you set it up.... For all buses maxing out around 4500 ish RPM,, approx first gear 0-20,second gear 15-30, third 20-50 , fourth 32-79... Mine is slower, its a 1641 T1 , because the 15 inch wheels are 5% smaller but the final drive ratio is lower with a T1, so my bus indicates 75 mph at 70 GPS mph, and will do about 75mph at 4600 rpm. With the progressive carb and a twin quiet pack it will actually rev to 5700 rpm or 38 mph in second...but not something I like doing despite driving my bus fast on average.. It will also happily pootle at 25mph in 4th and accelerate, but its not good being in a high gear and going slowly, better to change down and rev faster with more cooling. I find sensible driving easy because the 4500 rpm upper rev limit is the same as my 14 year old Peugeot 2.0 HDI.
I thought that its the colour around the electrode that you go on, rather than round the edge of the plug - they are all white, so running lean? I was thinking of putting a filter on the top of the idle circuit intake pipe as maybe its sucking in too much air? It is called an idle circuit, but does that mean its only concerned with the engine at idle (i.e. under 1000 rpm), or is that just up to 3000 rpm?
Funny, enough PIE, I've just finished checking the valve gaps - the exhaust were a little too large, and the inlet were virtually non-existent. I have gapped them all to .15mm (=6 thou) as I understand that they are not sodium filled valves (1700cc type 4, 1971, US spec. I have just ordered a small filter to go on top of the idle circuit intake tube in the meantime to see if that helps (actually, i've ordered 2 as I was also going to put one on the end of the crankcase breather pipe, as that is currently vented to fresh air as I do not have the OEM air filter assembly). the contents of the box that came with the bus (i.e. the old OEM air filter the previous owner took off) look like this.. Cam you still get the parts? (e.g. elbows, and the rubber joint between the pizza pieces and the central oil bath housing).
Update - changed the fuel filter & fitted a new dizzy cap & plugs. Did notice this though..looks a bit cruddy at one place on the brake servo pipe that goes from the manifold to the brake servo - the outer covering has gone though, as has the metal strengthening, although the rubber tubing on the inside doesn't look like its actually gone through (although it does look a little brittle). Can't feel or hear any leak from this point with the engine on tickover. Could this be causing the problem (the brakes are fine, but maybe a small leak may not affect them?). Any advice gratefully received..
One way to find out is to disconnect the servo tube and block off the hole in the manifold. If the idle speed slows afterwards then the hole is an air leak. You can always find pieces of round silicone hose from motor sports suppliers to stretch over odd oval shaped pipe connections to join all those elbows and boxes into a proper air cleaner. But I would suspect the biggest hit on your engines performance when hot was the valve gaps being too small. When the engine warms up the valves will fail to seal a d hot gas will be going the wrong way and burning the valves and seats. When you have the heads off, you will find the zero clearance valves will most likely benefit from lightly grinding in again. I can certainly tell when my valves need gentle regrinding, the edge goes off the engine even though the valve clearances are good. next time the heads come off , I have new valves to fit as the exhaust valves are pitted.
Update - i put the original oil bath air filter set up (that came with the bus) back on..and it runs like a dream. It will now pull comfortable from 25mph in 4th gear - loads more power, and if you do want to rev it, it pulls really well with no hesitation and actually revs properly. Many thanks for all the replies & info guys.
