Thread: Help...2L engine backfire with flame and power loss

Originally Posted by series1buff

When you install the dissy , it is a rather tricky job and it is easy to do it incorrectly and it isnt a easy thing to describe either lol .

The leading edge of the rotor arm must be just approaching the relevant ( No 1. lead ) connection inside the cap - with the timing mark on the flywheel at the correct position. When its set up correctly , looking at it, you think the rotor isnt close enough to the lead to work properly . The vacuum advance pulls the thing into the correct position , so it sparks at the correct point .

I had to fiddle with the dissy drive gear position and it took me ages to get it all lined up


Yours might be out of position, timing wise .

I used a vacuum hand tool and connected it to the carby end of the pipe , I watched the dissy mechanism advance as I allpied vacuum to the pipe

Mike

the manual makes it as clear as mud.... but the cam and drive gear remaind in place ,and although the timing chain was replaced ,the valve timing {and method} was checked by several people and cross referenced with lrsoc pictorial posts and set up with a dial indicator.
##Can the position of the drive slot change with the engine at 10 btdc and both no 1 valves closed{ as in if you wind it on past this point to 10 btdc with no 1 valves closed again do you get a different distrib position? }
## don't have a vacuum tool to check it{ if the advance unit works at all}

Originally Posted by wrinklearthur

Hi Mark

My first thoughts are; is the coil the correct 12 volt / or good healthy one as it maybe breaking down when it warms up?

The next thing to check is the points, look and see if they haven't come loose both in themselves or the advance retard plate they are fastened to, if that plate was stuck when the timing was done, the plate could have freed up it's movement throwing the timing setting out.

That advance retard plate should have a fine braided earth wire between the plate and the body of the distributor, make sure it isn't loose or broken as any other current path to earth from the distributor points can cause erratic results.

The last thing electrically to check is the condenser, best way to check that, is to change it with a known working one.

Drain the carby and watch for any water or dirt, a bottle of methylated spirits in the tank is a crude way of getting rid of a small amount of water in the petrol, flush the carby out and blow it clean with compressed air should sort any problems there.

.

ill dump some metho in the tank just in case but the fuel is fresh and the car was only engineless for 2 days.
ill pull the carbie off tonight and see if theres any contaminants etc inside..

Originally Posted by mfc

ill dump some metho in the tank just in case but the fuel is fresh and the car was only engineless for 2 days.
ill pull the carbie off tonight and see if theres any contaminants etc inside..

Metho won't do the rubber in your fuel system any good!

Have you checked the spark with a plug out and lying on the rocker cover, or another good earth? Even in daylight you should see a strong bright-blue spark; if it is weak, or yellowish suspect the coil, or wiring on the low-tension circuit.

You could also check the timing by whitening the TDC mark on the flywheel and pointing a timing-light at it, whilst someone else cranks the engine. I can't remember if the TDC mark is set for No 4, or No 1 piston but you can check by setting the mark and removing the rocker cover to see which one has loose rockers. The strobe should show you TDC somewhere in the aperture, you then need to work-out which side of the mark is advance,

Cheers Charlie

no 1 piston....
ill paint the tdc mark on ,gotta be heaps easier.
Its running again ,and I think its the extra heat from the loose{was} manifold and damaged gasket that caused the backfiring , but im suspecting that the acorn nut type lucas coil {removed atm and replaced with a later style lucas one} is breaking down with the heat from the exhaust leak and the extra heat under load. Make any sense?
regards mark

Originally Posted by chazza

Metho won't do the rubber in your fuel system any good!

Hi Charlie

I don't think a full 500 ml bottle of Metho in 45 litres of petrol would be too destructive in a one off application.
.

Originally Posted by mfc

Its running again ,and I think its the extra heat from the loose{was} manifold and damaged gasket that caused the backfiring , but im suspecting that the acorn nut type lucas coil {removed atm and replaced with a later style lucas one} is breaking down with the heat from the exhaust leak and the extra heat under load. Make any sense?

Changing the coil is the way to go.
What you can't see inside a faulty coil, is a couple of turns of it's wire that have lost part of their insulation and shorted together.
That shorted turn upsets the magnetic field of the energised windings causing heat to build up and the increasing heat further upsets the magnetic field, with it getting hotter until it collapses altogether.

A faulty coil, can get quite hot to touch.
.

Originally Posted by mfc

ill dump some metho in the tank just in case but the fuel is fresh and the car was only engineless for 2 days.
ill pull the carbie off tonight and see if theres any contaminants etc inside..

hi you should have a fuel bowl to check for sediment worth a check

hi Russell, I empty'd the sediment bowl a month ago but ill do it this arvo as well..
Arthur , problem is that the is an unknown item even though lucas and compatable. the black acorn nut one was fine two weeks ago and is fine until under driving load,thats what had me thinking that its the heat bringing out /magnifying the fault . the manifold leak{fixed} and manifold to pipe gasket were putting out a hell of a lot of heat, so mutch so that the guard surface of the wing was hot to touch after a short drive.
plus new engine mounts put the front pipe section in touch with the guard.