What have I done! (R4 GTL)

[petak]

All that was checked few times already.
Timing is set to 6°-7° with strob light.
Vacuum disconnected.
Vacuum is working fine. checked by suction, and by driving from 30 upto 80km/h in second gear without any problem.
Restriction is there,checked, new pipes put in.
It is still hot here where i am. 12 to 15°C in the morning.

I can put pictures when i get back home.
Only thing left is bad zenith.
Will put second renewed carb and see will be any diference.
Than i can open one that is on car now.
I am avoiding to mess with carb but it looks like i will need to do that also.

Appreciate your help malcolm.

 

[petak]

This weekend i have put second carb that i have. Also cleaned and set up at vacuum table.

Took some checks before installation.

Second carburetor Zenith 28 IF






Made 1,0 mm needle for choke adjustment




Needle position and checking for choke set up




restriction in T-joint to inlet manifold pipe

 

[petak]

Setting up gas pedal cable


choke cable


Connecting pipes




View inside



Only two places that are not tight are

choke lever that moves gas


and pipe that ends up on valve cover


Set up mixture screw to 1,5 turns out (540°), and drive it for while,
set up idle screw by ear
Again drive it for while but not so much to be certain is this one better than first one.
Will drive it two days, and then go to exhaust analyzer to set it to right CO and to right idle revs.

 

[JonathanT]

Olive harvest in progres today.
View attachment 17109

Family ocupation for next 10 days

Today we harvest 320 kg od olives.
Half of it in my lovely R4

View attachment 17110

I adore that car

How beautiful - reminds me of a trip to Bellisimi in Nirthern Italy. Olive groves all around.

Good to see you enjoying the weather family and your R4

 

[JonathanT]

Let's hope 2nd carb works better
All this ....so many turns out etc is in fact very variable one carb to another . Only the slightest variation on the hole or tapered pun would make the difference of a turn or two. Mine is only half a turn out

 

[petak]

Yesterday was playing again with my distributor, timing, carb setting.

Managed to put my hand on old engine analyzer instrument. Borrowed it from local car electrician that did not use it for years


And strob light - forum member BorgeB lent it to me while he is up north in Norway(thank you BorgeB)


tested before touching anything.

Strob light said +7°
Dwell angle was 51
idle 950rpm

Few days back i have received brand new vacuum advance from koleque mojobaby and decide to test my old vacuum.
Apparently old vacuum did not work as it should.
When i pull air from hose it moves but can not keep it that way for more than part of second.
I was thinking that it is how it should be until i watched mojobaby's movie
http://www.renault4.co.uk/forum/threads/vacuum-advance.8131/

That opened my eyes.
Throw away old vacuum and put new one in.

Adjusted point again. But this time used smaller gap 0,40 rather than 0,45 i used before.

Position for adjusting points


Gap after adjustment


Put all back together and warm up engine.

adjusted idle speed with instrument (idle speed was jumping a lot)
readings were 735/742/750/760/780/790/810


dwell angle was 54
(believe it should be 57 so thinking of adjust points one more time with 0,35 feeler gauge)

But when i rev it up (vacuum hose connected) dwell jumped to 59

Made short road test and i believe that have solved my problem with judder at low revs in high gear (60km/h in 4th)
Choke was closed full all the time. Did not have to pull it to drive normally.

Now i have few days to test it more in my daily routine....hope it is solved.
keep fingers crossed

Update soon!

 

[harbourseal]

Dwell angle is 56 + or - 6 with 54 you are doing quite ok

 

[petak]

Thank you for comment....
Than i will left as it is.

 

[petak]

Fast feedback!
This morning drive it to work (some 25km/h one way).
Cold weather 0°C with heavy north wind (it is called "bura" - strong and cold wind)

Took him long time to get to working temp (something that i could understand considering weather) but when finally reached 85°C tested low revs at high gear, and again i have juddering and hard acceleration (almost like he is struggling not to accelerate). It is even worse when i press gas pedal suddenly.

Could one of the reason of juddering be that i do not have air hose (do not have it at all - mine old was rotten and did not find right one to change it)?

I do not have idea what to do more to fix this problem.

Same thing i have with second carb.

Getting little bit frustrated about all this.

 

[mojobaby]

hi Petak, to me it certainly sounds like you have a timing issue.
I have never used a strobe to set my timing, so please explain something to me. If the strobe says +7 degrees, is that BTDC? Should it not say -7 degrees?

The symptoms that you describe above sound like the engine is too retarded

 

[petak]

There are marks on gearbox housing.



I have highlight them on picture according to discussion on this forum made by our forum member DavidN

Strobe does not tell you degrees.
Strob is connected to car battery and to cable from dizzy cap to first spark plug/cylinder.
And when "spark" goes thru cable from dizzy to spark plug, wire send info to strob to light on. It looks like flash on photo-camera.
In that moment mark on flywheel is shown somewhere between TDC and 12 (on picture).
By turning dizzy you adjust timing.

On this picture you can see mark on flywheel on my R4 sometime ago from one of many adjustments i have done. on picture mark is between 5 and 6.

 

[mojobaby]

Correct! I use only the 2 marks in the front and make sure that the notch on the flywheel is lined up with the right hand side front mark.

I don't think that you have enough advance, looking at the photo. And your engine is acting like it is too retarded.

At this point the points should just open. You can see and hear the spark if your ignition is turned on.

So if you look at the photo of your points above, turn the distributor body clockwise until the points close completely and then anti-clockwise until you hear the click of the spark.

If that is already what you're doing, then I apologize for giving you unnecessary advice.

 

[petak]

Did not done it that way.
I have just adjusted points when they are most opened.
Then started engine and turn dizzy while i get 6/7°with strob light.

So you are saying that i need to turn it more to TDC?

 

[mojobaby]

No, your flywheel (688 engine?) runs anticlockwise. You need to set the mark on the flywheel more to the right hand side mark which is away (before) from TDC.

TDC is the left hand side mark.

Adjust points when they are most opened, then with ignition on, turn dizzy clockwise to close the points completely, then anti-clockwise until they open and you hear and see the spark

 

[petak]

Thank you for clearing it to me.

 

[harbourseal]

Guys,
I might be wrong, but i think this isn't a timing issue.
Petak, you've got the timing about right. Dwell angle is okay you're advance is about right. But the juddering and lack of acceleration is still there. Maybe it is time to start looking elsewhere.
I think you are pulling false air in from somewhere in the system. A cracked connection or an ill fitting hose on the breather system is my guess. Or maybe the carburetor foot is not straight. Or one of the gaskets is leaking. Just a small leak and the there is something off in the air to fuel mixture balance.
I had some small leaks in one of the plastic connections and the rubber hoses of the breather system. Could not find anything by eyesight until i examined the hole breather system up close and found cracks in the plastic connections and in the robber hoses. I replaced the lot with new rubber hoses and new plastic connections and the engine ran fine again.

Don't bother with scavenging from other engines just replace the lot with new plastic connections from der Fransoze and new petrol resistant rubber hoses.
If it is indeed an air leak.

First try if the juddering stops when you apply a little choke. That means you are constricting the amount of air that goes into the carburetor.
Then check everything for cracks and damage. And if need be, replace.

good luck

 

[petak]

Harbourseal:
Yes, juddering stops when i pull choke just a little bit. NOt more than 2-3mm.

I have tested air tightness around carb, gasket and pipes with aerosol (starter spray) and could not find any air leak...engine did not react on spray.
Have changed T joint that goes from carb (brand new) changed hoses that goes from T-joint to inlet manifold (brand new), only old rubber hose is going from T joint to valve cover.
Did not changed small gaskets on carb base (where carb sits on manifold) and did not tested flatness of carb base. But noting had happened when i spray there with starter spray.
I can do it again.

It is symptomatic to me that car works same on all three carbs. Same juddering and same solution to that juddering (choke cable puled out for 2-3mm)

 

[harbourseal]

That you have to pull out the choke a bit means that you do get a little to much air in to your engine. According to some engineers I know, this is a common problem with the Zenith 28 IF and modern unleaded fuel.

What helps is enlarging the main jet. Just take out one of the main jets from one of your other carburetors.
Take a 1mm drill bit and push it through the hole twisting it by hand. Do not attach it to a power drill.
From the top of my head the standard main jet is 0.9 mm by enlarging it to 1.0mm you get just a little bit more fuel in and that balances the mixture.
And shuddering should stop.
It's worth a try.

On both my F6 and the Sinpar I'm running 32mm solex SEIA carburetors I don't have the shuddering problems. A friend of mine dit the enlarging trick on his GTL with a Zenith 28 IF and that helped him. He barely uses the choke. Just to start the car.

Just a thought have you tested the connection of the manifold to the engine to?

 

[jonigel]

Try blocking off the pipe to the m/fold below carb ,that upsets the mixture ,i have blanked off a couple of engines including my own runs fine.
As harbourseal said your dwell is ok at 54 but it should not go to 59 ,could be a worn shaft bush.

 

[Otto96]

I had simillar problem as you - juddering around 60 - 70km/h on 4th gear when accelerate. It was worse with more loaded car. I did some inginition and carburetor setting and it didn't help. Then I changed sparks last week (I drove 25000km and run rich for some Solex32/ Zenith 32 testing time on them.) It seems to be OK now.