2.0 Aircooled help

[billybigspud]

hi ppl,
just got back from a weekend with the bus and it is not behaving itself and hoping some of you can help. i will explain what it is doing. last weekend drove to kent and was backfiring and spluttering whenever it was put under load going up hills. the only way to overcome it was to drive just tickling the throttle.
got back, changed the plugs, leads and cap and reset and balanced the carbs again and it was running beautifuly. better than ever and i thought i had sorted it.
left this friday for the weekend and was fine until i started again in the morning and was even worse going up hills but fine going down them and on the flat. on the way home today i didnt think i was going to make it. started fine and drove ok until the first hill and then started misfiring and felt very restricted like i had tied the van to a lorry travveling behind and it was tryin to slow me up if you know what i mean. it just continued to do this all the way home. was doing 30mph at points and it is even doing it downhill now. if i pulled over and just idled for a minute and then continues it would be ok for about a minute until i got some speed up and then was doing it again. at idle it will rev absolutely fine and halfway home i adjusted the carbs to give more fuel and was still doing it. seems to be once it has cooled right down it is ok for a while.
any ideas as i just need to keep the beast going until the cold weather sets in and i can give it a good overhaul.

many thanks
jamie

[Footprint]

Sounds like fuel supply, as in not enough. If the fuel supply were insufficient it would run OK at low throttle openings, but struggle when you wanted more power and thus more fule flow, if you let it tickover for a moment or two then the float bowls would fill up again as the amount being used were less than that which were supplied - so it would pull OK again for a while until the fuel level in the float bowls dropped.

[billybigspud]

sounds good, filter then maybe or pump. how many litres per ? is the fuel pump meant to produce as i will work out how much is being produced.

[Footprint]

First check that fuel flows from the tank OK - at the pump end, take off the hose from tank and see that fuel runs out good and fast, not just a dribble, make sure the hoses from pump to carbs are similarly clear.
I don't know how much either volume or pressure that the pump should be capable of, but as yours is not a pressurised system as such - the pump is there solely to lift the fuel up a bit because the tank is lower than the carbs and a gravity system is thus not possible. I would therefore be surprised if the pump were capable of more than a few PSI - by which I mean perhaps 5 at most.

Considering what the pump is intended to do, which is provide volume rather than pressure, I would look for consistent sizeable squirts from the pump outlet, if there's just a dribble then the pump or pump pushrod is possibly a problem. Check the length of the pushrod first - they wear, which means the pump would not operate full stroke, supply volume would be the first and most obvious problem.
If the pushrod is OK then the pump must be suspect, which could prove awkward as I understand they are no longer available. Should that be the case then a conversion to an electric pump may prove the best option.

[billybigspud]

bit the bullet and put it into a specialist. got some other stuff i want sorted and i am fed up of having the fear of breaking down every time we go away. he said the engine sounds healthy and it is carb fuel problems. gonna save for some dellortos but he is goind to do his best with the solexes. someone has had a go with them before as the top idle screw has been replaced with a nut on a bit of thread. this guy is supposed to be the dogs doolies so i have full faith. someone quoted him as being a walking haynes . loads of splitties and bays outside his place wating for resto so that is a good sign. fingers crossed

jamie

[Footprint]

the top idle screw has been replaced with a nut on a bit of thread.

Are you sure?

Some have a stem with a hex round it, (which at first looks like a screw with a nut on it), some earlier ones have a large slotted screw.

[billybigspud]

yeah, it was a stem with a nut. cool, at least i know it isnt a bodge. just expected a screw. i could of eventually sorted it myself once i had found it but i have loads of camping trips planned and no time and really dont want to break down with the kids and i know scott will put his hands straight on the problem and sort it. going to do the electric fuel pump mod and put on the some carbs that i know and understand so i know it is sorted then and then get to know the engine better when the weather changes. try and remove as many weak links as possible.
thanks for the help, very much appreciated.

jamie

[Choppski]

yeah, it was a stem with a nut. cool, at least i know it isnt a bodge. just expected a screw.


Phew - i've just found the same in my engine!

[billybigspud]

yeah, it was a stem with a nut. cool, at least i know it isnt a bodge. just expected a screw.


Phew - i've just found the same in my engine!

doesnt look right does it. my advice, dont play with it.these carbs are so old now that you will never get it running 100% perfect without some work being done on em. i used to tune and balance all my carbs on my race bikes and feel very compitent doing so but they were in good working order. these things just done my head in with one side controling the idle on the side and three idle screws doing different things, let alone all the electricals attached to em i have never seen a carb so so many things you can adjust. dont really know enough about how they work to know if anything was broke if you know what i mean.

jamie

[Footprint]

See this: Linky link.

It's lengthy, but very very wortwhile for a real world way of adjusting the carbs without lots of equipment, as you'll read the timing needs to be set in conjunction with setting the carbs - so you will need a strobe.

Note that it's written with a Yank spec Bay as the example vehicle, as such it has some emmissions equipment that your bus probably won't have, but this does not change the procedure in any material way.

[billybigspud]

that my friend is a fantastic find and even an idiot like me could understand it.
fair play

jamie

[bigherb]

yeah, it was a stem with a nut. cool, at least i know it isnt a bodge. just expected a screw.


Phew - i've just found the same in my engine!

doesnt look right does it. my advice, dont play with it.these carbs are so old now that you will never get it running 100% perfect without some work being done on em. i used to tune and balance all my carbs on my race bikes and feel very compitent doing so but they were in good working order. these things just done my head in with one side controling the idle on the side and three idle screws doing different things, let alone all the electricals attached to em i have never seen a carb so so many things you can adjust. dont really know enough about how they work to know if anything was broke if you know what i mean.

jamie

Nothing wrong with the original carbs they work very well and are dead easy to set up as long as it is done in the right order.

[Choppski]

wow - that guy on the samba certainly thought about explaining things didn't he?

i'll print it out and read it about 10 times, hopefully information by osmosis will work!

[billybigspud]

had a look at what sgs has done to my engine and the vacuum hoses are plumbed in totally different to how they were. the two that come from the dizzy go to each carb but i thought one was meant to be blanked off. one goes from air box to maf (looks like a maf anyway ) and the other disappears over the back. the van has never run as good in fact it runs brilliantly. i was thinking is this a mod that other ppl have done or heard of before? i have no reason to question scott as what he knows about Aircooled engines isnt worth knowing. the guy runs a 600bhp type 4 dragster.
jamie

[BOXY]

Any chance of a photo?