Running as rough as a badgers behind

[Matt]

Following a head change my brothers 1098 car was running okayish but had low oil pressure, so he pulled the engine and put another used one in, apparently it was running very well before it was removed (but with 948 ancillaries),

The engine has been changed and we just cannot get it to run right, it hunts very badly at idle (from normal sort of idle revs down to one fire a second...) and wont rev. It was driven (albeit with a bit of difficulty to where it now sits and then pushed up a pair of ramps because it couldn't get up them under its own power...) but now its just cannot move under its own steam. It will not run without choke. The engine has the PCV type breathing arrangement

Any idea whats wrong? What we have done so far is:

Swapped carb for known good (from HS4 to HS2 involving manifold swap then another HS2)
Swapped distributor for known good
Swapped plug leads for known good
Swapped Dissy Cap for known good
Set the tappets
Checked compressions (about 170 on all cyls)
Turned the engine over looking for stuck valves
Played with the timing and fuelling from first principles
Swapped the exhaust for a mini one pointing out of the front
Probably a few other bits too that I cant remember

Has anyone got any ideas?

[Matt]

Oh yeah, swapped the spark plugs too....

[bmcecosse]

HT leads wrong order - 1342 anti-clock around the cap?

[Matt]

Yup plug leads are correct, I checked that several times (including swapping them about - it just wouldnt run in any other configuration )

[bmcecosse]

Can't see what else then - you've covered it all. Maybe it's the coil........

[d_harris]

Coils been replaced with known good too

[Matt]

As well as an additional earth (AKA a jump lead between block and engine), and a direct feed from the battery to the coil...

[chrisryder]

is it possible that the timing is way out? if you can get it to run, try a strobe, if not try it statically (although i've never got on with trying to time statically...)

[beero]

"runs only with choke"
Suggests very weak mixture, leak on inlet manifold??

[Mogwai]

The engine has the PCV type breathing arrangement

have you tried isolating the breather ?



I could pop over sometime if your stuck

[bmcecosse]

Good point - I missed the bit about the PCV.

[Matt]

Yup its the same if you block the breather arrangement and new gaskets were useed when swapping the manifold, these have subsequently been stripped right down, each gasket covered in sealant and reassembled - no different.

We have set the timing statically and strobostropically and it makes no odds

[Mogwai]

as there's not a lot left to check, can the pump flow enough fuel and to pressure it may be ticking but not pumping.
also how good is the petrol ? contaminated, old etc

[d_harris]

The fuel pump is definatly pumping, and filling the chamber quickly. The fuel is about 3 weeks old...

[bmcecosse]

Only common factors I can see not mentioned so far are - rotor arm? Not using a 25D rotor in a 45D dizzy - not even sure if that's possible!? Not using silly electronic ignition? Wire between coil and dizzy - try a jumper lead. And was ANYthing done to the engine - timing chain./cam swap? I suppose if all still fails you will need to check the cam timing - it's not unknown for worn engines to jump a tooth or two. You need to check that both valves on say #1 are open exactly the same amount when #4 is at TDC on firing stroke. No dial gauge? Set valve gaps on #1 at 40 thou - then crank the engine round until #4 is on firing and 1 and 4 are at TDC. Measure the gaps on #2 now - they should be the SAME (within very few thou) - doesn't matter what the gap is - but must be=. Really can't think of anything else!!

[Matt]

Mogwai nipped over and offered a fresh set of eyes... Thanks very much!

The car is running an awful lot better now, not perfect but its down to fine tuning teritory (after fixing the exhuast blow and the rocker cover leaK).

Unfortunately we did multiple things at the same time so cannot be sure what cured it. It was either a new condensor, LT lead or ditching the breather system.

Its really odd because the PCV system had been previously bypassed and the dizzy that got put in was fine in the previous engine, so we are not sure what was at fault

[Mogwai]

And it ran even better when we remembered to put the rotor back in

[Matt]

Shhhhh!