Ignition Timing on a F6 Engine C1E J 718

[DavidN]

Hey experts,

Your help is highly appreciated!
I still have to fiddle out the correct ignition timing on my 1985 1108 F6 engine.
It is the 688-11 / C1E J 718 engine with the low(er) compression rate of 8,3.
This engine is rated 34hp @ 5000 RPM not like the GTL engine that delivers 34HP @ 4000 RPM.

Fitted is a R324C33 FEMSA distributor with matching advance curves.

The ignition timing on this engine seems to be a bit of a mystery.
According to the Haynes Manual it should be 2-4° BTDC.
Other (e.g. the M.R.) states that it has to be 6° +/- 1° BTDC (like the "normal" GTL engines with their high compression).
I'm kind of insecure about these different data. :neutral:

One thing all the different books have in common though - The pictures and figures of the bellhousing and the timing marks are as unclear as can be.

I attached a picture that I took of the bellhousing.
(I marked all the ignition notches I found).

I know the process of setting the timing...
- Disconnect vacuum advance unit
- 700rpm idle speed
- Use a stroboscopic timing light
...

What I dont know is...
- WHERE exactly hast the mark on the flywheel to line up with on MY engine?
- Where is 3 Degrees BTDC
- Where is 6 Degrees BTDC
- What are all these marks for? Is this just one mark per degree?


Thanks for your help!!!

David

 

[R4 Felix]

Hello David,
I've just consult an ex Renault garage manager.
There are 3 types actually, and yours seems to have the lower compression.

He assumed (it was a very long time ago) that the correct order is that. ( = pic 1)
BTW: there is a missing mark down there - red colour.

The timing mark on the flywheel should look like that. ( = pic 2)

But, it doesn't really matters.
Nowadays, we use high octane unleaded petrol, so the whole timing is incorrect anyway.
What is the problem exactly? missfire? backfire? bad sound? bad performence?

 

[DavidN]

Hi Felix,

thanks for your investigation and your figures!

There is not really a serious problem. I just want to do it right when I change the distributor next week.

The car initially had a very very early ignition timing (the mark on the flywheel was barely visible on the very left side of the opening in the bellhousing). It must have been somewhere between 8 and 10 degrees BTDC. It ran powerful and without any unusual noise and accelerated perfect though. Just the idle RPMs have been a bit too high and the car felt a little "jerky" when running steady RPMs.

We adjusted the timing to about 4 degrees BTDC and the (warm) engine ran even better. The idle RPMs dropped to a "normal" rate and the "jerky" feeling at constant speed(s) was gone.
BUT when I started it the next day, the cold engine was running VERY bad. Before our adjustment cold starts where not a problem at all. I could even put the choke in right after the start and the engine ran smooth and powerful.


@Angel
Can you confirm what Felix' mechanic assumed?



David

 

[R4 Felix]

Dear David,

Have you checked the contact points? are they ok?
The correct gap should be about 0.4mm.

I strongly recommend you to buy an electronic ignition kit.
The engine runs so much better!!!
Have no more irritating contact points to adjust and change! :smile:

Changing the distributor is a very easy job.
You pull out ignition cable no.1, to remember the correct order.
Mark with a pencil (on the body) where the vacuum little hose was.
Replace it, and that's all!

R4Felix.

 

[malcolm]

For my GTL I tend to have the dynamic timing (with the vacuum advance disconnected) somewhere between 0 and 4 on Felix's diagram. See http://www.renault4.co.uk/tech-points.htm Modern fuel doesn't like so much advance as the manuals recommend.

It depends a lot on the distributor. I've found a good one, but most of the ones I've had didn't really work properly. My strategy is to set the timing as mentioned above, then go for a drive. Find a hill, select a high gear and see if the engine pinks (a ping ping noise from the engine that can damage it horribly if left to continue). If it does then retard the ignition, if it doesn't advance it a bit until you get the pink, then retard it a bit until you don't.

Or for the GTLs with 28IF carbs which are prone to pinking retard the ignition so you only get pinking if you select a ridiculously high gear for a steep hill.

 

[angel]

David, as I have a 1108 engine lying around in pieces in my workshop, it's very easy to calculate exactly the position of each mark. More on this tomorrow...
As I have a timing light with de-phaser, I always adjust ignition timing taking reference from the TDC mark, so i never needed to remember what each mark meant.

I used to set the Jogging engine (supposedly of high compression) to 6-8 deg. BTDC, and I never noticed any pinking, despite the summer heat and the poor quality fuel that is available here (it must be mixed with too much water, or what? :-D) . It ran nicely, although it was a bit jerky on overrun, exactly as you describe. However, when I checked it on an exhaust gas analyzer, it had relatively high hydrocarbon emissions at idle (expected when having too much ignition advance). So I retarded it to about 4 deg. BTDC, HC emissions came to more or less normal levels, plus I haven't noticed any difference in power or fuel consumption.

 

[DavidN]

Dear David,

Have you checked the contact points? are they ok?
The correct gap should be about 0.4mm.

I strongly recommend you to buy an electronic ignition kit.
The engine runs so much better!!!
Have no more irritating contact points to adjust and change! :smile:
...

R4Felix.

Felix, contacts are worn out and in fact I plan on installing an Ignitor electronic ignition kit!

These kits are not availlable for FEMSA distributors so I have to change to a Ducellier which is no problem.
I have already taken the Ducellier apart and cleaned everything. I still need one of the springs holding the advance weights because one is streched.
(I'll get another Ducellier distributer within the next days as a "donator".)

For my GTL I tend to have the dynamic timing (with the vacuum advance disconnected) somewhere between 0 and 4 on Felix's diagram. See http://www.renault4.co.uk/tech-points.htm Modern fuel doesn't like so much advance as the manuals recommend.

It depends a lot on the distributor. I've found a good one, but most of the ones I've had didn't really work properly. My strategy is to set the timing as mentioned above, then go for a drive. Find a hill, select a high gear and see if the engine pinks (a ping ping noise from the engine that can damage it horribly if left to continue). If it does then retard the ignition, if it doesn't advance it a bit until you get the pink, then retard it a bit until you don't.

Or for the GTLs with 28IF carbs which are prone to pinking retard the ignition so you only get pinking if you select a ridiculously high gear for a steep hill.

Malcolm, thanks for your tips!
I think, that my FEMSA distributor is indeed worn out. The dwell angle is not constant. I've got about 60% dwell on idle RPMs, when revving the engine up the dwell angle falls back to about 42%

But I will replace the distributor anyway...

I will see if I can hear a pinging noise after setting the ignition.

And of course I know your valuable tech tip about setting the timing. The problem for me was that the pictured bellhousing and it's timing marks looks so different than the one of my engine and that I was unsettled by the diverse data provided by Haynes & M.R. about the timing on the F6 engine.

David, as I have a 1108 engine lying around in pieces in my workshop, it's very easy to calculate exactly the position of each mark. More on this tomorrow...

That would be awesome, thanks Angel!



Thank you all for your help, I will keep you posted on my success (or failure) with the ignitor.


David

 

[angel]

Here is what I found today...I fitted the bellhousing of the first photo on a 1108 engine I have on the bench and attached a timing wheel to it. The two large marks are TDC and 6 deg. BTDC, so the smaller ones are spaced to 1,2 degrees each (!!).
This bellhousing was actually from a 354 R5 gearbox, so I compared it to the one in the second photo (attached to a R4 gearbox) The marks are exactly the same, but extend further as the "window" is larger. So the three bottom marks are TDC, 6 deg and 12 deg BTDC.

 

[DavidN]

Thanks Angel!

So there is just the question whether to set the timing on my low compression engine at 3° BTDC or 6° BTDC.

 

[R4 Felix]

The setup that sounds better. :smile:

 

[DavidN]

You are probably right.
I think I will careful aproach to the best timing using Malcolm's method, and beginning with 3° BTDC. Let's see how far I can advance the ignition.

David

 

[DavidN]

Okay, here is a quick follow-up on the timing / ignition issue on my F6 van...


First of all I wanted to get rid of the old FEMSA distributor.
I converted a F6 Ducellier distributor (R324C33) to pointless ignition using a system similar to the Pertronix Ignitor.

I took everything apart, cleaned every single bit and reasembled the distributor.

The electronic ignition unit fits the Ducellier distributor nicely.

Just the dust-cover had to be modified to fit the electronic-box.

The outside it is pretty much original looking. Just 2 cables and no more condenser.

Adjusting the timing was not that easy though.
I had to guess a "starting point" as the electronic ignition could only be adjusted by using a stroboscopic light on a running engine.

I set the timing to about 3° BTDC (per manual) and the engine ran smooth and quiet without any pinging noise. But it behaved very "powerless".

So I advanced the timing step by step until I found the perfect timing adjustment for the low compression F6 engine.
This is it now...

I still don't know what BTDC it is exactly that I'm running, but to be honest - I don't really care as long as the engine is running fine.

David

 

[Steve Hennessey]

Well done - very nice modification. It would be great if there was a DIY box of tricks to do away with the vac advance unit altogether.

You have also done what I have been doing for years - that is to adjust the ignition timing until the engine pinks and then turn it back a couple of degrees.

 

[nicky4tl]

@ steve. would this consist of some device to measure engine vacuum electronically and then adjust the timing?

 

[Steve Hennessey]

No - this would be a small computerised device programmed to advance the timing accordingly and would replace the function of the vac advance and mechanical weights.

This is already being used in the expensive 123 distributors that have already been discussed on this forum. What I was hoping was a cheaper version - even a home build kit. Boyer Bransden already make kits for motorbikes and I suggested to them some years ago that their mechanical bits could be easily adapted to fit inside a R4 distributor. They do have the capabilities to programme one of their computerised units to suit R4's.

Unfortunately, despite me sending them drawings and ways they could adapt e.g. a Honda kit into a Femsa distributor, they sent back a curt reply to say it wouldn't work. That is complete tosh but in these austere times when companies need to be more flexible in their approach, they may at least consider it especially if there are firm orders and the price isn't too silly.

There is always the ever willing Chinese to approach if all else fails............

 

[nicky4tl]

right. I kind of follow, just back from a quick read on timing points etc. is all the information the distributor needs contained in the rpm? What provides the information the vacuum supplies?

 

[malcolm]

Wouldn't you need another input to do vacuum? The distributor already has engine speed, but it needs an input to tell it to back off when you use full throttle up hill as the GTLs are prone to pinking. That would need to be vacuum or throttle position.

Megasquirt are a DIY open source ECU system that will take a vac input, but seems over-complicated for a 4.

 

[nicky4tl]

thats what I was thinking malcolm. i thought throttle position wouldn't work as it wouldnt indicate engine load?
where does the vacuum for the distributor connect to on the 4 by the way? Does it come from the carb? This is wonderful stuff.

My 845 doesnt have any vacuum carry on, (at least i don't think it has)

 

[malcolm]

Race cars don't have vacuum advance either - it's assumed you will be on full throttle all the time. 850s are much the same

The 1108 engines run with a weak fuel mixture. The vac is essential on those. Us new-fangled R4 owners have a take-off from base of the carb that connects to the vacuum advance on the distributor. Throttle position is used on most modern engines, but it needs to be mapped to timing and engine speed using computer chips and the like. DIY mechanical version with a properly worked out lever would probably be very close.

Edit> missed a post - I think some of the the 123 stuff has an option to take a vacuum input.

 

[angel]

Can you tell us more about that electronic ignition David?

I had bought an electronic ignition from here: http://www.ignitech.cz/ some time ago in order to fit it on a 2CV. It didn't work correctly for some reason (that neither me not the manufacturers could find) but I have kept it and am planning to fit it on a R4 at some time.
This one could be linked to one more input signal apart fron engine rpm, to map the ignition advance curve. On the 2CV I fitted a throttle position sensor, but an MAP (manifold absolute pressure) sensor could have been fitted if desired. The end result (what the ECU senses) is exactly the same.