Thread: S.O.S - Series III not running right

Originally Posted by Roverwill

Hi everyone,

just chasing your advice on tuning my fantastic/ pig-of-a 2.25l petrol Landy. When I bought the vehicle a couple of months ago (with a genuine 112,000kms on the clock) I thought a simple tune up would cure it's rough running ( I wish ). It can be difficult to start, needs excessive use of the choke, it sometimes idles erratically, it often misses/jerks at lower revs and even by Land Rover standards, is slightly underpowered and drinks like a sailor .

A reputable LR mechanic has checked compression and all is good and even across four cylinders. Points, plugs, leads and fuel filters have been renewed. The timing has been adjusted and checked, a carby kit has been put through, the air cleaner has been cleaned and he has tried to tune it but the problems persist .

Any ideas on how to sort it? Would I be better of replacing the horrible Zenith with another type of carby for better performance/fuel economy eg. a Holley or Weber? I know a good one should run very well so any advice on low key mods or what to check would be hugely appreciated

Cheers - Will

P.S I don't want to solve the prob with a blow torch and a Holden Motor

you checked the vacuum diaphragm?

if it needs heaps of choke is may be running lean, checked filetrs and pickup tubes?

the webers are okay for street cars, no good offroad... holden carbs with adjustable main jets are okay.... a diesel is better :P

its not just bad fuel is it.....like water in the tank...?




have you had a look at the distributor...?
it may be worn or damaged and causing erratic timing........or it may have a stuffed rotor button......
is the coil and all the wiring to it ok....?
try running a wire to it straight from the battery to see if it makes a difference......
another problem which is hard to see is where the wire from the points to the coil runs through
the rubber block into the dizzy....this sometimes breaks inside and causes all sorts of fun and games
such as you have described.....

sounds like the problem will be something very simple......


do you know any history on the vehicle....?
has it had the cam out for any reason....it may be out a tooth...?

Check all of the above + balance weights and springs in the bottom of the dizzy, change the coil, check tiny earth wire fiber wraped(contact breaker earth connector) atached to the contact breaker moving plate. type 25D6 dizzy the one with a neat adjuster nob for the vacuum timing.
If all fails remove the front engine cover and check the timing chain and chain tensioner. It may sound daunting but its only simple basic mechanics.
Be afraid not of the darker side.!!!

Recent problems with my S2a turned out to be plug leads. They were not very old and still looked new. New plug leads made a world of difference.
John

There is a known problem with the Zeniths that they leak around the big O ring between the top and body. This lets extra air in.
You have to be certain that the top and body are not warped by rubbing on glass with sandpaper on it.
If you cannot get it flat, then a new carby is the go.
There is a mob in UK that supplies an SU and inlet manifold.
The recomended Weber in UK is apparently too small.
Hey I have a Cortina carby 32/36 DGAV with electric choke that I bought for a Vitara which I sold before I put it on. Fully reco, extra jets, Pancake air cleaner,Unifilter,and adaptor. Sell for $200 pick up Sydney.
Regards Philip A

G'day Roverwill
The Zenith Carb has a wear problem with it's Throttle Shaft, as it wears the body, and lets extra air in, it can be bushed by a carb tech. or if it is worn (you can check by moving it vertically by hand) you could try wrapping some teflon tape around it, (thread tape) the other problem is the "O" ring between the airhorn(top) and the throttle body, that must be in good condition as it is a compression seal between each other, the bodies have to be flat,PhilipA has given you the go that.

The mixture screw settings for both the Zenith 36 IV and the Weber 34 ICH are opposite to the good old Holden Strombergs.

IN- (clockwise)== Weaker. OUT- (anti clockwise)==Richer


Float height: with airhorn upturned on flat surface with float attached, the measurement between the body and the highest part of the float is 1 5/16 (33 mm) the easy way is to measure the specs and cut out a piece of cigarette packet !_ and measure it that way. If you are unable to do it a competent Carb tech should be able to, parts are scarce in Aust. So you may have to contact Burlin Industries in the UK

hope that is of some help
cheers.

try the age old trick of searching for a vacuum leak , get wd40 or a similar type of spray and spray around manifold , carby and all vacuum joints hose,s with the engine running and when the engine revs slightly higher or runs smoother

do this a few times untill you have found the source

Originally Posted by rangieman

try the age old trick of searching for a vacuum leak , get wd40 or a similar type of spray and spray around manifold , carby and all vacuum joints hose,s with the engine running and when the engine revs slightly higher or runs smoother

do this a few times untill you have found the source

works well with aerostart......



its not anything silly like fuel delivery....pump cutting in and out....?


if you turn the ignition on and manually open the points with a screw driver....
are you getting a healthy spark....?
dont forget.....even new points out of a box can be faulty.....

and what about the rotor button....?
have you checked that...?
check also that the carbon contact in the dizzy cap is there and its not jammed up in its little hole....


does the engine have spark arrestors and egr valve...?