These carbies are drivin me crazy!!!

[Rokkitt]

Hi all,

Be gentle with me - this is my first post...:)

I have a CSW V8 with the twin SU HIF carbies and for the past few months it has had me running in circles. I have had to replumb the fuel tank due to a botch job done by the previous owner - I now get 2 litres of fuel pumped to the carbies every minute (guessing that should be plenty) - I have fitted a fuel pressure regulator which is set correctly according to the manual I have. The carbies have been fully rebuilt by a specialist and I have fitted a new after market distributor (high power scorcher) however the car continues to cough and splutter under load. Up hill generally and it seems to me that the bowls empty on the carbies and then the coughing and spluttering begins, I pull over for less than a minute and hey presto I can go again but not far before it starts again....no issues downhill!!
I have attempted to tune and balance the carbies but I may have done more harm than good, it seems to me that it can't be anything else - the balancing was way out which I corrected using a borrowed unisend - I then went on to adjust mixture, this is where it got difficult!! every mixture adjustment changes the balance again so it goes on...an endless loop of adjusting mix and then re-balance....again and again and again until I hit the end of the screw movement - the mixture screws are all the way in and as far as I can tell it is running lean but when I pull out a plug and check the end of the plug is blackened and shows obvious signs of over fuelling.
My car still needs to be tuned and timed but it is fairly undriveable so a mechanic is out of the question - so I need help and/or advice on this issue frrom the more experienced landy owners.

Thanks in advance for your comments and suggestions.

Regards
Rokkitt
:cool:

[Bigbjorn]

If you can't find a mechanic, likely over 55-60 years old, who is skilled with setting up multiple SU's, then buy "The SU Carburettor High-performance Manual", by Des Hamill, Veloce Publishing 2006. Pit Stop Bookshop have it. This has a full section on initial set-up of multi-carburettor engines. Also, have a look for "Tuning S.U. Carburetters including full needle charts", Speedsport Motobooks 1975. This may be out of print and could possibly be found on the second-hand market, swap meets, e-bay.


Now, the world is full of self-appointed SU experts. When you get them properly set up, surround them with a ball of barbed wire, and do not let anyone, including yourself, touch them. Fiddling produces failures.

[Sly]

You can try getting a kit and rebuilding them yourself, I paid a fortune to a recomended shop to have my stage 1 3.5 refurbished & balanced and they only made them worse. So I was stranded west of Kununurra, in the wet. Organized a kit through the local repco, rebuilt both carbies (learnt alot ) roughly retuned by eye and ear (limited facilitys on station) only had genuine manual to read and had them vac balanced when able to get to town.
Also changed all the linkage balls to metal ones, to remove any slack.

[Davo]

These set-ups are notorious for causing grief when people start "hit-and-miss" tuning. Try getting everything back to stock standard, including the dizzy. Sometimes these engines don't get along with aftermarket stuff. Carbies should be the last thing you adjust during a tune. You have to know your ignition is sorted first, which should include replacing the coil so that you know you have a good one. (In fact, it helps to have a few parts on hand in case you got a dodgy one.)

I would also check the fuel pump and return and get them back to standard if necessary.

As recommended above, you should also get a kit and rebuild the carbies yourself - just so you know it's been done. After that, you can then go through the handbook for setting up.

The thing with these setups is that if you aren't methodical, working through the job in steps, then you never really know what the problem could be. Ignition and fuel problems have been known to impersonate each other and cause people to go running around in circles until they buy a diesel Toyota!

[Carslil Jim]

It sounds to me that you have a fuel supply problem. Agree with others to try and put everything back to where it was, but that is often hard. The key here is she splutters under load.

If it was an ignition problem it would probably always splutter under load, but you say a short pause and you can put her under load again....and she goes for a short period and then splutters. Sound like she uses all fuel available and then sucks air.

First check all fuel filters from tank to Carbie. One blocked filter will cause this syndrome. If you find a filthy one...thats it.Dont forget some tanks have a filter built into the bottom, but start from the Carby and work back to pump, and then tank.

Second check the Carbie fuel bowls for crap. eg rust from tank. That can block jets. How it bypasses filters is beyond me, but I have suffered from it.

If filters are clean, then check the pump is delivering a good steady stream (into a bucket). No hazards eg smokes, static electricity, electrical connections etc. If the pump is good, then next is carby tune.

I have triple SUs on my E-Type which would sound like a nightmare to balance, but it is really quite simple. If we get to that, we can use the manuals referenced in replies, the LR manual, or my triple instructions.

If it still splutters...I am wrong, it must be ignition.

I am assuming there IS plenty of petrol in the tank..:)

Jim

[Bigbird]

SU carbys = nightmare best thing you can do is unbolt them and toss them into the nearest river!!!this should stir up a bit of ****,but my experiance with SU carbys is unbolt and throw away ,i like strongbergs personally some people put holleys on but i am not a fan of holley carbys either,i have had many experts rebuild my Su carby but never did i get it running good and i am a mechanic!! .

[Rokkitt]

Thanks for your responses, the carbies will go eventually but for now I have to put up with them - I have even read of a few success stories with them.
I do have good fuel flow and pressure (fuel pressure reg fitted and 2ltrs of fuel gettin to carbies every minute), as far as I am aware the ignition is as good as it can be (new coil, dissy, plugs and leads) - need to make sure the supply voltage is good though.
Only leaves the carbies, it seems like an obvious fuel supply problem to me but as I said it's good; so it's gotta be the carbies!! it's just gotta be...:)) I am ordering the book as sugested although previously I have looked at these manuals and thought they are like computer manuals - if you can read them, ya don't need them.
Question's - Once the carbies are balanced should the fuel mixture screw affect the balancing, if so would it be a big change? I have them balanced really well but when I touch the mixture screw the balance is affected severely and I have to readjust the balance.

Thanks again.

[mark2]

I have twin SU HIF's on my V8.

I had a very similar problem which turned out to be the seal in the choke poppet valves. They dont use a butterfly for the choke, but a dribbler system which will run very rich if the seals are gone. The previous owner had it looked at by many mechanics and no one could solve the issue.

I ended up removing the choke valves altogether and sealing up the external recess with JB Weld. - this solved all the issues. I give it a shot of lpg when starting on petrol on a cold morning which works well.

I'd also suggest checking the slide by removing the three screws holding the top cover on and checking the slide is not binding in the housing. The best way to check it is to hold it horizonatally and spin in it in different positions. If it is binding , some careful of use of very fine wet and dry (1500 or finer) should free things up.

They are actually very simple and reliable carbs and I prefer them to Strombergs because there are no diapragms to split and they dont tend to lose the damper oil like the strombergs do.

[Rokkitt]

Do I need petrol in there?? aahhhh - wish it was that easy, when I first got the car it ran out of fuel ewvery twenty minutes even though there was fuel in the tank....took me 6hrs to work out the hose had come off inside the tank and the pick only went down about 40 to 50mm.....:) been an interesting journey with this car and I haven't been anywhere yet...lol

[Carslil Jim]

I saw your reply, but before I give up, one more question. You say you have lots of pressure from the pump, but do you have good constant flow at the carbie inlet, after all filters have been passed? :)

[Rokkitt]

I saw your reply, but before I give up, one more question. You say you have lots of pressure from the pump, but do you have good constant flow at the carbie inlet, after all filters have been passed? :)

I put a 0.5 litre bottle on the end of fuel line and switched the pump on - the fuel flowed very smoothly and filled the bottle in 15 seconds.

[Davo]

And you've got the fuel return hooked up and flowing well?

[Rokkitt]

And you've got the fuel return hooked up and flowing well?

Yes, it is flowing fine - have fitted a fuel pressure reg on the return line but I can hear it trickling steadily into the tank....I have found a guide on the internet describing the start point for tuning and then where to go from there - will give it a go this weekend, things can't get any worse.

Regards
Rokkitt

[Bigbjorn]

Have you got good enough spark and happening at the right time? Waste of time fiddling with the fuel system if you have not got a good ignition system.

[Rokkitt]

Have you got good enough spark and happening at the right time? Waste of time fiddling with the fuel system if you have not got a good ignition system.

Hi, I replaced the dissy with a new scorcher unit, new high output coil, new magnecor leads and a set of shiny new champion plugs. Timing is set as directed by the supplier of the dissy (10 degrees before TDC) - my only concern is the input voltage on the coil as the previous owner has messed with the wiring, lights fade in and out at idle!!

[Rokkitt]

Does anyone know of a mobile carby tuner in Melbourne that is good with these carbies?? would be nice to get it running before I pull the motor to do the clutch.

[Davo]

I'm probably nagging here, but put the standard ignition stuff back in - just so you know that's not it. I have read of problems with aftermarket distributors. Some engines are fine with them and some aren't. People have had similar symptoms to yours that seemed like fuelling and found the distributor was the problem.

Without electronics, these engines don't have that much to go wrong and a boring methodical approach is the easiest in the long run. Don't get too frustrated - you'll get there in the end!

[Rokkitt]

Hi,

New clutch is in, motors is all connected back up and I am now back to the carbies - can someone with a known good setup send me a picture of how the hoses from the carbies should be connected??
On mine there is a hose from each rocker cover connected onto the carbies - breathers I assume.
Then there is a hose from the nearside carby for the advance retard vacuum.
And also a hose from the front of each carby that were just hanging down the back of the motor - I am connecting these to the std air filter.
A photo would be great but if anyone has the time to type out how it should be connected.

Thanks in advance
Rokkitt

[Carslil Jim]

Rockitt,
I am far from an expert on carbs but here are three pics that may assist. I have put coloured tape on the pipes for info.

Pink is the pipe to the rocker cover
Thin White tags on the links to the emission control container
Red is the main fuel supply
Thick White (on the thin black pipe that links the two carbs)...beats me

There is another diagram of the emission control unit in this thread Advice pls re 1985 V8 County Fuel system (http://www.aulro.com/afvb/90-110-130-defender-county/95889-advice-pls-re-1985-v8-county-fuel-system.html)

Regards
Jim
1985 County

[Blknight.aus]

Yes, it is flowing fine - have fitted a fuel pressure reg on the return line but I can hear it trickling steadily into the tank....I have found a guide on the internet describing the start point for tuning and then where to go from there - will give it a go this weekend, things can't get any worse.

Regards
Rokkitt

ahhhhhh

what kind of fuel pressure regulator is it?

some go into the return line some go on the supply...

put them on the wrong side and you wind up with either not enough fuel or too much.

[Rokkitt]

After months of experimentation I found the problem; a cracked intake manifold - only found the problem after swapping the engine though...:((
When I swapped my SU's onto the new engine the problem came with them - swapped it back to the single weber and the problems gone away and the car is straightforward to tune.....
Lots of white smoke when hot got me suspicious as the replacement engine was known to be good..
Finally got to drive the car....woohoo!!!

Thanks to all for your suggestions.

Rokkitt

[Carslil Jim]

Rod,
CONGRATULATIONS!!! What a bugger. At least we now know another frailty of the County!!

I may compete to get operational for Easter. I dont have much to do now.

[sashadidi]

Not sure if at all relevant at all and I apologise if it is not I remember my v8 would fart and miss off the line mainly and in lower revs espically when cold and thought was all sorts of things running lean etc, fuel problems etc etc, one day I talked to a old english machanic who told me to put sae 30 oil in the carb pots (where needle is from memory) s so the needle would lift slower and run slightly richer (instead of sae5? light oil from memory) ran as smooth as a sewing machine after that and no difference in fuel consumption, he said they were hard to get to run right but this helped and it sure did!!!