B200K maybe carb fault finding

[jtbo]

Some of you might know, but here goes short history of car, skip to problem part if it is familiar.

Car in question is 1988 360 GL with B200K, it has been sat for quite some time, I bought it in 2003 (or was it 2002?), it had trouble with part throttle and some kangaroo effect as well as dieseling then, could not get it to run any better so I did convert car to run fuel injection and also I did install Megasquirt 2004, car did run really well with that. But things did go wrong when I did take car to well known motor specialists company that put K-cam in, car did run well, however it started to leak oil and company did not take responsibility from this. So car was not used much at 2005 and from 2006 it has been completely unused mainly because of oil problem.

To current problem then, 2010 I managed to cure oil leak, also I did decide to make car such that it would eventually pass historic car registration. So I have been trying to get it run properly. I have two z11 carbs, one has used for something close to 400k km, other one is car's original and has been used for 224k km.
With car's original carb car starts and runs quite ok, but it says poff/puff/pop quite frequently on idle and even it does not hesitate anymore it is not pulling smoothly at part throttle car is shaking and struggling to go 80kph, but when I push throttle more it starts to run better, it is missing power at part throttle.
With other carb it runs very nice and all, but it is quite weak and when I push throttle quickly it is not very responsive, carb has warped base plate and it has not been serviced properly, all base settings and adjustments have been completed.
I have straightened original carb's base and cleaned whole thing, checked jets and made sure that everything is according to specs, but it seem not be operating well at part throttle and at idle, even it is nearly perfect in full throttle, when shutting down there is quite somewhat of dieseling even idle shutoff solenoid does work properly, with not original carb there is no dieseling.

I have carb service kit, now I should decide what to do, do I install it to original carb or other carb?

Then there is this original carb's problem, I would imagine that it is related to idle circuit, last summer engine would not idle with that carb at all, so there is something with idle circuit, however I have removed yets and I have blow compressed air to every hole, also I have used brake cleaner and some Pineline stuff that cleans even hard oil from side of engine, but there seem not to be effect, maybe idle passage has been tampered someway before I got the car? Has anyone, who has more experiences with carbs, had carb that idle system have been broken so that it causes such problems? Has it been unrepairable?

So I'm bit worried that install new gaskets and all is not doing any good for car's original carb, but also I don't know if other carb will be better option as it is more worn and base is quite warped.

Also when straightening base of carb, is it possible that it would mess idle circuit somehow?

I have also book that tells a lot from carb servicing and problems, but haven't been able to find answer from there.

Naturally ignition parts are all new and in good condition and fuel is new too, and as motor works with other fueling it should not be impossible to make it work well with this carb, but I think I have met a wall here and need some opinions from those who have worked lot with these carbs

[pyro]

To current problem then, 2010 I managed to cure oil leak, also I did decide to make car such that it would eventually pass historic car registration. So I have been trying to get it run properly. I have two z11 carbs, one has used for something close to 400k km, other one is car's original and has been used for 224k km.
With car's original carb car starts and runs quite ok, but it says poff/puff/pop quite frequently on idle and even it does not hesitate anymore it is not pulling smoothly at part throttle car is shaking and struggling to go 80kph, but when I push throttle more it starts to run better, it is missing power at part throttle.
With other carb it runs very nice and all, but it is quite weak and when I push throttle quickly it is not very responsive, carb has warped base plate and it has not been serviced properly, all base settings and adjustments have been completed.
I have straightened original carb's base and cleaned whole thing, checked jets and made sure that everything is according to specs, but it seem not be operating well at part throttle and at idle, even it is nearly perfect in full throttle, when shutting down there is quite somewhat of dieseling even idle shutoff solenoid does work properly, with not original carb there is no dieseling.



Naturally ignition parts are all new and in good condition and fuel is new too, and as motor works with other fueling it should not be impossible to make it work well with this carb, but I think I have met a wall here and need some opinions from those who have worked lot with these carbs

SNAP!
mine does exactly the same, it piddles oit out from the rocker cover cap, (even with a new seal and that padded out a bit) nearly no power till full throttle (or close) basically whats just been up there!

JTBO - is yours drinking petrol aswell?

Ben

[jtbo]

I have no idea how much it uses petrol, it is so long since I have been using it on road that I have pretty much forgotten how much it did drink, but I guess it was something like 8 to 9 litres for 100km when driving was mostly at city.

If you have oil coming from rocker cover cap, then I would check breather and after that leaks from valves and from piston rings, something must build pressure to make it leak there.

[Ride_on]

There should be negative pressure in the crank case. Undo the oil filler cap with the engine running but do not remove it, try to lift it with finger tips, you should fell a slight suction force holding it down which suddenly releases when you put on enough force. If you are not getting vacuum check the oil separator and flame trap are not blocked, and that all the pipes to the inlet are present and not loose/leaking.

[pyro]

sorry to jack this JTBO, but its kinda related!

ive got positive pressure in the rocker cover, ive flushed all breather pipes out, cleaned flame traps in parrafin and an air hose and still a trickle of oil out from under teh filler cover at idle (you can actually see it running down the head onto the manifold) if i take the cap off there is a little fountain of oil spurting off the cam. (its never done that before. on anything ive had!)

so, piston rings (its only done 68k and regular services) valve guides/seals/actual valves. ??? hopefully running a compression test tomorrow which may give a clue, if anyone has a tester in the area they would like to lend me id be grateful

Ben

[jtbo]

Or faulty head gasket/cracked head? Let's hope not.

I have spent this day just thinking about my carb issue, but still can't think nothing else than faulty idle cirtuit

[jtbo]

What do you say to this then?

I started car this evening, just half hour ago and let it warm up, gradually pushing choke in as car did warm, just thinking there how perfectly choke seemed to work, it did work well previous time too, much better than ever before even many so called professionals had looked the carb. So after engine was enough warm to run without choke I pushed it fully in and car did run bit different than before, I would say it did idle bit difficult and lot of popping, so I thought that it is perhaps good to do idle tuning yet once more, so I did start the procedure as explained in my carburettor book, making sure I did run motor at higher rpm after 30 seconds of adjusting and carefully following the procedure. What I did found out was that idle mixture was way lean, I got easily 300rpm more by turning idle mixture screw, thought that was odd, I had done same procedure some time ago already, should not act like that.

So I did complete adjustment and now motor runs lot better, no popping or coughing at idle. However I have no idea how it runs on road, testing it on road is bit problematic as it has no MOT, so I have to do it when it is quiet time.

However it is odd how it now acts different, maybe there was something blocking idle circuit and now it has gone? Further test are needed to verify this. On yard it seem to be running as always, maybe less prone to stall when not applying throttle, however as there is still quite a lot of snow and yard is quite soft I can't go more than walking speed and only few meters of that, bit difficult to test how it runs.

Just came to my mind, I have to check that small breather hose that it has not got loose again, that affects quite a bit to mixtures, it was already so dark that could not see much out there

[jtbo]

I think that I did fixed it, seem to be running really well, also for first time ever it actually needs choke until it is up to normal temp, starts easy, runs smooth, still need to learn a bit of choke usage, it is now quite sensitive to level of choke applied as opposed to how it was when last time on road, it really did not care if I used choke or not. Would imagine that fuel economy is now better too, at least I don't need to apply lot of throttle to go 80kph, which is quite scary with those old headlamps, gears are smooth, it has strong idle and it quite easily finds it, however there is still bit of dieseling, don't know if valve adjustment and some miles on road would cure that.