Firing on 3 help!!!

[Perryman21]

my nova c20xe dizzy type running twin webbers sounds like it's running on 3 cylinders spluttering on any kind of throttle. I've took off and checked all ht leads and cleaned inside dizzy cap but still same any advice please where to try next?

[Andy]

Could be anything from shafted plug to a broken piston.Start with a compression test and go from there.Has it been set up properly?

[Perryman21]

The carbs are not set 100% but not far off, it still ticks over fine and I drove it back at low revs fine bit soon as I tryed anything more than 40% throttle it splutters. I'll check everything again today if still same ill book it in for test.

[Andy]

I wouldnt start it til its set up.if its too far either way youl balls your engine royally.

[therealnovaboy]

pull each plug and test the spark on each plug. if your not getting a spark on one of them then fix that its an ignition problem. if you are getting a spark on all of them pull each lead individually until you can trace the cylinder that doesn't fire. you should be able to hear when the note of the engine changes from three cylinders to 2. if the note doesn't change then that will be the cylinder that's not firing. pull the plug on that cylinder and compare it to the other plugs. compare it with the others IE wet, dry , black , white. swap the plugs and see if the misfire moves cylinder. if it does then its a dodgy plug. If it is still the same faulty cylinder that isn't firing and the plug looks different to the rest its probably fuelling issues. check you do not have any air leaks in the cylinder that would cause it to run lean IE test the inlet and carb gaskets and check that all the vac points are in use or plugged.

If you have a compression tester do test the compression first if not try all the above then do the compression test. if the compression test is fine then you need to take the carbs to somebody that knows how to adjust them. if its fine at idle and gets worse with RPM then its probably the mixture not a compression fault but easier to find out with a compression test than adjusting the carbs.

[Perryman21]

Thanks alot mate, I've changed plugs and dizzy cap today did buy leads but was too short. All plugs was dirty and black but still runs exact same can get up to speed so v slowly. its booked in garage Tuesday for compression test if I haven't sorted by then. I'll try taking leads off then 2moz while engine running see what I find. I'll keep you posted thanks again

[therealnovaboy]

sounds like the fuelling. get him to stick the emissions tester up the exhaust to see what its reading.

[Perryman21]

Garage phoned me earlier to say he had a play with the dizzy cap and if perfect now, I'll find out more when I collect it 2moz. It's having a service while it's there with new wheel bearing :)

[Perryman21]

After picking up the car it's far from running perfect, I put a tank of shell v-power in it the day before it started playing up could that be half the problem. Is 99 too good for the older engine? just a thought

[tothemark]

Agree with realnova, check your fuelling, nowt wrong with 99 for that, what fuel pump are you using ? do you have a regulator on it and or a fuel king, I had a red top in an astra and was using a red top facet to pump my 45's on dizzy, worked fine. Have you ever had it running fine before or is it a new purchase i.e. what history you got because maybe somethings changed in the set up.
I bought a car offf a guy who got rid of it because he said the lumenition just wouldnt work on the dizzy and under load it would cough and splutter, he gave up on it, when we got it, it turned out he had the fuel regulator the wrong way round !

[Perryman21]

I bought it 2 weeks ago and drove it back from Sheffield brilliant. As it's on carbs and had no rev counter I'm worried I reved it too hard, cuz I gave it the beans in 2nd shifted to 3rd and then it spluttered, I thought a lead had just come lose. changed all leads plugs and dizzy now, Still same. Not sure what fuel pump on it but it's got some sort of fuel regulator under the bonnet set to number 3 as when I bought it. There's also a fuel pressure gauge in the car which usually sits just under 6 not sure what it's measured in.
passed compression test and got spark on all 4. There's a motorsport garage said will have a look at carbs n ignition timing as I explained to then the right cone on each Carb are sucked much more the the 2 left carbs and when I put my hand there earlier I got neat fuel out the carb on my hand.
I've had redtops before but totally new to carbs

[tothemark]

Webers are easy to work on, your float chambers might be sticking from crud that has been sucked in or it could be overfuelling.

Take the filters off and leave the fuel pump running and see if the carbs are leaking from the bottom, that could mean its either over fuelling or stuck floats. Wet filters you said seem to confirm that.
First easy option is to look at the fuel regulator, is it a shiny chrome one like an oven knob ? You could turn this down to 0 and see what its like - i have one on mine set to zero and its pumping out at 2.5 - they are very inaccurate. So could be overfuelling that way.

Otherwise take the tops off the webers and blow some air through the float chamber to try to clear any crud, must be a youtube video on that.

2 to 1 on that its fuel problem and not spark.

[Perryman21]

Yh does look like an oven knob haha I will turn it down and try on 0 see what happens. When you say remove filter is this the fuel fitter and of so not sure where that is on here.
Smells like neat fuel from engine and exhaust so Prob is fuel related and poorly set carbs just adding to it. I'll post some pics 2moz while I'm having a look