Stuttering performance carb problems?

[nomisthewise]

I've rebuilt everything on my newly restored van but every so often it will briefly splutter then be ok again. Not always when it's under load either

Engine fires up well and sounds sweet. Newly adjusted tappets ,carb has had a complete clean and overhaul new jet,needle rt etc. Ive put so much new stuff on the car as it was a basket case restoration! New needle valve, float, braided fuel line,new fuel pump, new fuel line to tank, tank spotless inside. New fuel ( with additive lrp), new points condenser, ht leads plugs.
However it's still occasionally spluttering and I have run out of ideas as everything that could go wrong is new........


Help! Anyone got any suggestions?

[bmcecosse]

I would be looking at bad connections - especially at the coil and the dizzy.

[chrisryder]

or swap the coil for a 'known to be good' spare. i've had a coil pack up slowly and it started with the occasional miss, then the occaisonal backfire!

[Neil MG]

Is it an HS2 carb?
Bit of a long shot and would normally only be at high revs but check the carb jet to float chamber pipe rubber o ring seal. Sometimes the old seal does not come off with the jet and can get squashed inside at the float chamber and restrict fuel flow.

[bmcecosse]

Good economy tip then!

[nomisthewise]

Interesting idea chrisryder. Ref coil Though problem is it's a new coil and the car has only done about 200 miles so unless it's faulty I can't think that it could be oil? Unless I just try yet another one for the sake of a few quid

[bmcecosse]

It's 'never' the coil.......

[chrisryder]

if the new coil said 'Lucas' on the box, then it's probably faulty! The one i had start to fail was a Lucas one, it lasted a week! The replacement has been on over 6 months and is going strong though!

[nomisthewise]

Thanks for the coil pointer Chrisryder. Turns out thats what it was. I went to Charles Wares of Bristol who had had a number of coil failures with the same coil. Turns out that the coils were under filled with oil by the manufacturer, so when placed horizontal not all coils were covered hence overheating coil and breakdown.
Bought a new bosch coil from them now works fine.

Think best to buy a good make in first place!

[nomisthewise]

Oh dear still had probs. Got mate to look at points seemed to make difference. But then disaster took out for test drive tonight started spluttering again on and off. One minute it was ok next it spluttered. came back and lifted bonnet saw drops of oil splattered on heater hose.

Looked at side if head and theres liquid bubbling out of front left and left at rear. Might be head warped? I changed head gasket the other day after some emulsification of oil. checked all torques meticulously

Anyone got ideas?

Bang goes welsh rally at st fagans on sun by look of things!

Maybe i should get new unleaded head

[bmcecosse]

Don't bother about 'unleaded' unless planning doing high mileage with hard driving. Did you retorque the head after the first heat cycle? So -it wasn't the 'coil' after all ! Look instead for loose connection - or condenser/rotor arm/dizzy cap..........or some recently have had great success with a new Low Tension lead inside the dizzy.

[nomisthewise]

No didnt retorque head didnt know you had to.
Its only done about 40 miles since did gasket
but i suppose its not worth trying to tighten it down to see if that works? Or is it a gonner?

[MarkyB]

Try it and see, you have nothing to lose.

[bmcecosse]

Torque to 45 ft lbf - and reset the valve gaps - 12 thou inlets and 15 thou exhausts. Don't worry about a little bit of bubbling around the edge of the new gasket.

[nomisthewise]

45lbft? Interesting... Book only says 40..is this ok?.

[bmcecosse]

45 ft lbf will be fine for the 're-torque'.. Later engines with flanged nuts and dimpled (or 'Y') studs are torqued to 50 ft lbf.

[nomisthewise]

Ive also just found it helps to stop blowing up your coils if you have an engine earth strap!.......

Funny that! No wonder i was getting through so many!