Zenith Carb is mine knackered possibly?

Hi there, I have just bought my first Series, an 82 2.25 petrol with a Zenith carb. First of all, I think she is a great piece of kit!

I bought it knowing it may need a new carb at worst but thought I would try and do a cheap fix first. Basically it won't idle and just stalls out when the throttle is let off even when warm.

I stripped the carb, cleaned with 30psi and carb cleaner, removed all crud, fitted new inline filter and then re-fitted. Still giving the same problem (the engine has new HT leads, coil, points). I fiddled with the idle screw and it made little difference to the engine behaviour at idle. The throttle linkage had loads of slop in it and I read on the net this can lead to idling issues. I also found that the little diaphragm under the small plate on the top of the carb was looking pretty slack and knackered, possible culprit? (not sure what it does?). Also the plate to which the carb was bolted to the inlet had a weird bolt sticking out of it (see pic), anyone know what this is for?



My question really was is it a) worth getting the carb refurbed bearing in mind it has slop in the throttle linkages? Would a replacement diaphragm be worth a shot (about £8) Or should I just buy a chinese copy for £60 as I won't be doing mega miles in her? Maybe a Weber instead?

I know replacing the carb may not fix the idle issue but having seen its condition I guess it needs attention anyway. I've ordered new plugs as they were showing white residue on the electrodes and soot on the outer edges? What would that be signifying?

Cheers
Alex

You say that you've had a bit of a fiddle with the idle screw. Have you tried screwing it right in then backing off 2 1/2 turns and then adjusting it a bit at a time?

Have you also static timed the engine, as that can make a huge difference?

No doubt someone more sober than I am at the moment will take over with words of wisdom.

Hope this helps a bit.

Googling Zenith Land Rover carb issues will help. And leave you very bewildered as to what to do. Currently in the same boat as you with my S2a and it's Zenith. Found a geniune unused original as a replacement, but many favour fitting a Weber instead (straight swap pretty much). Loads on this forum alone, so have search.

You may even find an explanation for the bolt, it certainly won't be the last oddity you find attached to your Land Rover!

Thanks guys, I'll try backing it out 2.5 turns and see how it goes. I've never timed a 4 stroke engine before but it will be interesting to give it a go, i have strobe gun so I'll check the manual for the procedure.

Your right about the oddities you find on these land rovers , the yoga mat being used as noise insulation on the transmission tunnel for a start!

If all else fails i think i am going to buy a new weber, i don't need the performance!

Cheers
Al

I have done about three hundred kilometers on a Padocks Zenith copy with no issues so far.
It couldnt have been easier to set, just followed the Haynes manual and the Petrol engine setting up on page 8 of the Common Faults and Questions section

my series 3 done exactly the same have fiddled with the idle screw so many times now ,have bin thinking of buying a new one but do they come set up already or would consider paying some one local to come and set it up for me

I fiddled with the idle screw and 2.5 turns and around results in no idle still. It just seems to an air leak and your probably right about timing as it pops on overrun. New carb is a bit of a luxury but sod it i am going to bite the bullet.

I will repost when i get one ( zen copy or weber) and let you know if its a worthy outlay. For me it will be as its such a pig to drive as it is. I just need to learn how to stop putting it in reverse now instead of first!

TBH i enjoy fixing things more them using them sometimes, cant beat it.
Cheers
Al

looks like its a common thing dodgy tick over and popping on overun and getting first gear not reverse let me now if you get it sorted very interested

I have plumped for a weber Typica lly for me i have cut a corner and bought a 2nd hand one
will report back if it fixes my issues or brings up a new one

I fitted my 2nd hand weber and predictably it wouldn't run right. A strip down revealed about 2cm deep of crud in the float bowl. I cleaned it all out plus all jets only to find the idle or mixture needle screw thing was bent! Anyway the carb was only £10 so i had a go. The car runs ok with the weber but it won't run well at all unless the choke is fully out. So either that needle being bent is a problem or its blocked up inside somewhere.
So now i either get a new needle or rebuild kit or just fork out on a new carb . The latter i feel is the go. New weber it is.
Anyone got any ideas on why a weber 34ich would run only on the choke?

Well i have ended up with a working condition zenith instead of the weber and original zenith. Just threw it on now in the dark avoiding hail showers and it idles now albeit lumpy. it needs a proper install plus im going to fit new plugs, points, condenser, time it, check valve lash and see how it goes then.
We are approaching some form of driveability now. Unfortunately under torch light i could see the exhaust manifold is leaking, interesting.

Sounds to me like you might just have an air leak. I'd get a new set of manifold gaskets, carb gaskets etc and rebuild the lot...should not cost much and shouldn't take long though I'd spend some time cleaning all mating surfaces and checking they are true and not cracked.

If you're going to stick with the weber I'd get a rebuild kit if it was full of ****e it will need a good clean through and the rebuild kit comes with all the bits you should need.

D

I've been thinking there may be an air leak from the inlet manifold or possibly the little adaptor plate for the Zenith carb. It has that weird bolt through it which is all a bit strange.

I attempted to static time the engine today and just couldn't get it right. I have an old 25 Lucas dizzy (my car is an 1982 so this is weird?) which is pretty well used by the looks and has a bent pinch bolt. When I was turning it to see where the points would open it wasn't really looking right somehow (rotor was moving in bits). I connect one end of the light to the coil LT terminal with the LT lead disconnected but all that happened is the light stayed on all the time! Does the LT lead need to be connect to the coil and dizzy whilst doing this? I timed it by looking at the points opening then put it all back but the engine won't fire up now. To add to my timing fiasco I accidentally pulled the dizzy out of the engine a bit then put it back in so I am guessing I have fouled up the timing a fair bit! The dizzy is a good 15 degrees anti-clockwise to when I started out so I've done something stupid somewhere.

I'm not happy with the state of the dizzy anyway so I ordered a new one and will fit that up just as a service extra. I ordered a 45 Lucas copy and after checking it seems it will fit in ok?

I'll get the timing/dizzy sorted then check for air leaks on the inlet manifold and see how I go. New gaskets is a good shout, thanks.

Its not fun doing this amongst rain showers and darkness descending at 4:30
Al

Winter landy maintenance - oh the joy! Yes, the 45 lucas is the dizzy you should have and it ought to be impossible to fit it the wrong way round (the drive pegs are offset). You can even set the points in the warm and dry before fitting. Note the position of No.1 HT lead and set the dizzy up to about the same place. Don't forget the dizzy goes anticlockwise when fitting the HT leads, the order is cast into the manifold. It should run over a fairly wide range of timing, you can static time or get it warm and do it by ear. If you've taken the carb apart it's best to replace the gaskets 'cos they'll leak if reused. Get the refurb kit and replace any spindles/bushes/diaphragms/needles as appropriate.

Thanks oxides will do that.
Cheers

Well I received my new dizzy this evening and with the missus and the baby away for 2 nights I set up the floodlights and installed it. Its an electronic one from SimonBBC. I fitted a new coil as well. Before this the car had been running rough even with the replacement carb and I was worried this was going to be a job chasing problems around to get the motor running nice

BUT

Oh my god has that new dizzy made such a difference. Before I was turning her over maybe 3 or 4 seconds before she fired, lumpy idle, stalling, poor in the cold, just unpleasant.

I turned the key just now after putting the new coil and dizzy on (also new NGK plugs and timed pretty much at 6BTDC) and she fired after about a quarter of a second. Literally straight away (probably due to all the petrol-soaked carbon deposits from it running on the choke for ages ).

I'm so chuffed. Not taken her for a drive yet but she ran like a bloody sewing machine, no missing, no coughing, just smooth as you like.

Those electronic distributors are £50 well spent I tell you :clap2:

I can finally take her for a proper drive yey. Until I get to the next job on the massive list........re-hanging the drivers door, then sorting the reverse gate springs, sorting the 50 oil leaks, re-painting, fitting a tacho, cleaning (well maybe not that last one).

zenith page

This takes you thru step by step, once you've found your type of carb ...(should be on a metal tag on the carb body)...




http://www.oldengine.org/members/diesel/ZenithCarbs/ZenithCarb.htm

Land Rover FAQ - Repair & Maintenance - Series - General - Tuning the 2.25 Petrol


Land Rover FAQ - carburetor CFM
this linky is for performance carbs - or to check that you have what you should have