Zenith 28 If problem again

[djenka]

Hi everyone ,
I am glad to find this site..you can't imagine how much.
I own R 4 GTL from 1987 . Is was made in Slovenia. I own it for 6 mounths. Ok previous owner didn't take much care. So there was a lot of rust etc..it is partly taken care .
New distributor car , new spark plugs (Sagem Eyquiem) , new cables , filters etc etc...
Problem is next : fuel consumption is about 8-11 liters per 100 km. *I must say my family owned 3 R4..since 1978 until 1998 , so I know a lot about them .*
Engine is shaking too much when idle . Strobo test is ok .
I visit some carb service..but here in Serbia it is hard to find someone who knows. Some of them sad..hm...my english is not so great but I will try ..they say that there is a space between main throat and panel..hm.panel that moves when you press accelerator pedal..I hope you follow me ..and there is a air suction .
I tried...many thing but no result. And..i read posts about Zenith..and...I have few questions..first you mentioned screew with spring..hm..there are two..on is for idle speed I think !? If I am right other one is for mixture volume ? Let's say it is . I tried to screew f all way but no result..just a little bit change...and then unscreew it totaly..and then engline stops.
May be important...I have T pipe...blocked...I have pipe from engine into the athmophere . Other smaller pipe which goes from engine is blocked too. But I try put new pipes...unblocked all...same story...
Also imporant fact..I have no garage...my R4 is outside whole winter...and I have no problem with starting in cold mornings...at -15 Celsius he starts in few seconds.
Is there any solution ?

Thanks
Djenka

ps : How to send image of my Zenith ? It might be much easier for you to understand my problem .

 

[malcolm]

If you'd like to add a photo use the "manage attachments" button below the window where you write your post.

The fuel consumption does seem high. I would expect 6 to 7 litres per 100km on a long drive (40-45mpg), but I wouldn't be surprised if it doubled driving through town.

A good starting setting for the mixture screw on the body of the carburettor is to screw it completely in and then back out by 1.5 turns.

Check the choke opens fully - the cable can slip and make the car run very rich. Also have you fitted new ignition points and set the timing? That can make a lot of difference. Is the air filter new?

The breather hoses from the engine to the carb would originally have been fitted with a restrictor. I don't know how important these are for the mixture. Probably if the holes where the hoses attached to the carburettor are blocked off it should run reasonably well.

I don't think wear around the throttle valve would have a big effect on fuel consumption. It could cause problems at idle, but doesn't sound like it's your problem.

Has anyone changed the jets in your car? If the rest of the carburettor and ignition works then it's a possibility that someone has fitted richer jets.

 

[djenka]

Thanks for quick answer .
I know it is high consumpion because my old R4 GTL 1986 was able to run 1000 km with 65 lit .
I will try to turn screew completly and then return 1.5 turns.
Choke...that is intresting..because when is choke little bit on car works great . No shanikng , good aceleration whitout clugging . With choke off there is a little bit of clugging at 2000-2500 rpm .
As I know no one was changing jets.
Thanks again I will write again .

Djenka

 

[malcolm]

Running with the choke out would make for poor fuel economy

Sounds like the ignition timing might be too advanced. The cars were designed for leaded petrol and the ignition would need retarding by about 4 degrees from the figure in the manual to run with unleaded. I set mine to 6 degrees advance instead of 10 degrees.

Another possibility is that there is an air leak into the carburettor. I'd be surprised if the wear you mentioned would be enough. If you've removed the vents from the engine check the holes into the carb are completely blocked. Otherwise it's common for the gasket between the inlet manifold and the cylinder head to fail and that can cause a weak mixture and poor running.

 

[djenka]

I cant wait to try your suggestions. But as I sad I dont have garage and it is snowy weather here..so I have to wait few days.
It could be gasket it is worn a bit .
Ignition timing..hm..I think it is ok because I am using leaded gasoline with 98 octanes..
Now can you tell me which screew is for mixture ? Is it one with arow pointing at it ?

 

[malcolm]

The one with the arrow looks like the mixture screw.

 

[djenka]

Ok I will try as soon as snow stops.
I would like to do it myself and then to go to so called carb service and say them few words about their knowlage !!!

Many thanks....we will be in touch.

i will try to upload some pics of my R4..with aloy wheels and stering wheel from R11 Turbo...Pioneer MP3 etc...

Best regards from Serbia

Djenka

 

[djenka]

Here are first results
I try to adjust mixture screw as you sad...ok I have to adjust idle speed also...but the engine doen't work well below 3.000 revs. Above 3.000 runs perfect. Below 3.000 just cluging and shaking much more. To get it work ok I have to pull choke .
But , gasket on manifold is torn on edges , so I supose there is main air suction. I have to fix that asap.
Strobo test is ok , igniton coins new , air filter new , distibutor cap new , cables new...
I wish you live a bit closer to me ...
New result coming soon...

Djenka

 

[Steve Hennessey]

It sounds that you do have a weak mixture and there are various reasons for this. Malcolm has already suggested that the engine could be sucking in air through the manifold gasket or the carburettor gasket. The best way to test this is by starting the engine and running it at 2000 rpm. Then dribble some oil or WD40 around the gasket areas and look closely to see if it is being sucked into the engine. Oil is better to use (although messy) as if it does go through the engine via a leak, you will see a puff of white smoke from the exhaust and the engine may hesitate slightly. If the oil is being sucked in, you know what you'll have to replace.

If the gaskets are OK, then you'll need to look further. The other cause of a weak mixture is badly seating inlet valves. This may be due to the valve clearance being too tight, so check these first. Then remove the spark plugs and carry out a compression test. All readings need to be within 10% of each other. The test will also show whether the head gasket has burnt through across two of the cylinders. Let us know the results of the gasket test first and then we can guide you through the compression test if you're not sure.

Steve

 

[John Doe]

Thanks for quick answer .
I know it is high consumpion because my old R4 GTL 1986 was able to run 1000 km with 65 lit .

One time I did 1110 km with 65 liters.
Concerning your problem I would say that you should check ignition timing. And put some photos as sun as possible, after all we are almost neighbours

 

[djenka]

Ignition...hm...well strobo test is perfect...only to try manualy..a little bit to the left a little bit to the right...
It doesnt seem like air leak on the gasket...I cant find new gasket so I have to make one.
Where are you from John Doe?

 

[John Doe]

I'm from Krasevo, a village between Doboj and Teslic, Bosnia and Herzegowina
P.S. My R4 was also made in Slovenia.

 

[malcolm]

Silly question - are you doing the strobe test with the vacuum advance pipe (from the distributor to the carburettor) disconnected. That's the right way.

Also is the vacuum advance working - when you plug it back in the timing should change a lot.

I've a feeling the inlet manifold gasket is shared with the exhaust so it'll be one of those metal ones - tricky to make.

 

[djenka]

New moments. Bad moments.
Today test shows that ignition is too early. But the distributor cant be moved. It is stuck . That is one thing. Next , gap between ignition points was too small . And finally biggest problem is that 2 cilinders doesnt have einough mixture. White spark plugs on two cilinders close to cabin . Now I know I shuold adjust valves .
This is too much little problems that makes me crazy !!!!