Carburettor / CO2 settings and ignition timing

[Bear]

I am a newbie to the 4x4 world and just purchased my first 4x4 last year October. I have a 94’ with a 2.2 4Y engine.
I am getting the carburettor tuned this weekend. The choke doesn’t work. I was told that the CO should be set on the gas analyser about 0,5. From my knowledge I’ve learned to use 1 to 1.5.

The ignition timing I think is about 10 degrees BTDC as per the owner manual and I think it's for coastal regions.
Back in the day there was 98 octane fuel and the turn-up settings were for 98 fuel.
We now run 95 octane so that should change the ignition timing by a few degrees, and living inland (Gauteng) may need an extra few degrees extra as well.

Can any of the experienced guys provide knowledge on the subject?
Thanks in advance.

[The Legend]

Ricky I don't know what the CO2 ratings is but the timing on the reef is 12 degrees BTDC. The flood level must be in the middle of the glass on the carb

[Bear]

Good morning.
Thanks for the advice. the guy who serviced my carb said the timing was set at 10 degrees BTDC. he said the engine was a bit 'slow' .
He tried 12 degrees and said it was a bit slow as well. He finally set it to 15 degrees. The truck seems to go more free now. Is 15 degrees ok?

He finally set the CO to 1.1 and it varies to 1.4. The fuel level in the chamber stands at the half way marker in the glass, however when the engine is running it goes up to three quater in the glass. Is that ok?

[Mars]

Hi Ricky

If the ignition is too far advanced it can cause the engine to start running hotter. Just look out for that but if it is usually between 10 to 12 degrees BTDC then it should be fine.

As far as the level in the float bowl is concerned I also don't know the specific model well but to my thinking it would be ok if the level is half way when the enigne is off. When the engine is running there is vibration that "distorts" the fuel level. As petrol is sucked from the float bowl the needle valve will open and will regulate the level. I don't think that a level rising to 3/4 is indicative of a problem. If the float level becomes too high the mixture will become very rich and will eventually flood the engine if the needle valve does not seal at all.

Hope this helps.

[Mud Dog]

15° Advanced is a bit too much with a standard cam .... if you have a longer duration cam then it's ok.

The float level sight glass has a half-way marker and that's where the level should be when the vehicle is on a level surface, that's at all times, running or not. The fact that yours creeps up to the three quarter mark means that the needle valve is leaking and it will be running too rich. Replace the valve, they're not expensive.

[Bear]

Thanks guys for the advice.
Do you suggest I take the timing to 12 degrees? Should I just replace the needle valve or do a complete carb kit?

[Mud Dog]

Just do the needle and seat if there are no signs of weeping, especially around the acceleration pump that would indicate a leaking pump diaphragm. If the butterfly bushings are worn, a kit is not going to rectify that.

Once you have your float level sorted I would check how the timing behaves at 12° BTDC as opposed to how it behaved before. At 12° it should be running strong. The important thing is that it doesn't ping under load (stressing piston and con-rod bearings). You can advance it a degree or two at a time and check for pinging - when it starts to ping take it two degrees back.

If it's not pinging at 15° I have a strong suspicion that there's a modified cam in there.

[Bear]

Hi Mud Dog. Thanks for the input. Just a little more clarification, please.

I never had a problem before with it set at 10º. I was just trying to get it perfect. From the little knowledge which I have I know that the timing needed to be changed when the fuel swooped from 98 to 95 octane, not sure by how many degrees though. Factory specs I think are for coast lines, and because of the altitude difference inland it also needed to be changed further as well.

The engine just feels more ‘free’ on acceleration know at 15° compared to 10º.
I drove the vehicle ± 40 km and I didn’t notice pinging. I have a problem with a hard start in the mornings after the tune up, not sure if it’s the timing.

Usually modified cams give an off idle. This seems to be smooth.

You say ‘at 12° it should be running strong’. What do you suggest I should set it at?

[Mud Dog]

First thing is to change the needle and seat to get the float level stable.

Then look at the timing .... maybe 15° will be OK if it doesn't ping but remember that the further you advance it the more strain you put on the pistons and con-rod bearings - advanced timing is also one of the primary reasons for difficult starting.

Once you've sorted the float you can play around with the timing to achieve a happy medium. My 4Y had a Brospeed branch and at the coast with 95 octane it ran best at 11 / 12° BTDC.

[Bear]

Thanks, will change the float, then the timing and advise on the performance there after.

[Bear]

Good morning
I overhauled the carburettor yesterday at S.P. Carbs. They striped the whole thing and put back together with new parts. They do not have a timing light though and set it by ear. Although it seemed there was nothing much wrong with it before, the performance is much better now.
The fuel level in the sight glass now sits at the half-way marker, however in the morning the level was just about a millimetre high in the sight glass and when I cranked the engine the level went to the half-way mark. Is that ok?
When I engage the choke it now revs at 2000rpm. Is that ok?

[Mud Dog]

Float level sounds like it will be OK. I would still keep an eye on it from time to time.

Choke rpm of 2000 is too high. Is it not an electronic auto-choke? - It can be adjusted.