just driving into work this morning and after about 10 miles when starting to acellerate, the engine would cough a little. as i sped up the revs would go up as normal but then drop off fractionally, the exhaust note change slightly then continue fine.
it happens in all gears around the 5000rpm range
afterwards its fine going a constant speed.
any ideas?
possible plugs or coil?
thanks
chris

Fueling or valve clearances too tight.

However if you have a points distributer check the condenser is OK and fitted tightly and you have the correct points gap for the type of distributor you have.

I had a similar problem years ago on a 1600 crossflow cortina, traced it to a bad contact on the earth wire between the advance/retard plate the points sit on, and the distributor body.

As the vac advance kicked in the connection failed.

I had a similar problem, that would eventually end in a total breakdown, i beleive to now be fixed !!

I was using a ballasted coil, on a non ballested wiring loom, and the coil would overheat and stop working, so a possible coil change for minimul money would be a good idea

well i felt i should reply.
im on electronic ignition not a dizzy.
it just seems to be number two not firing right, well possibly
the idle screw on the carb doesnt seem to do anything and when i put my hand over the intake it only has a dismal suck and the engine still runs, (if i do it on other cylinders the engine will stall).
could an air leak be the problem? or is this still possibly a valve gap problem?
its also breathing very heavily and the catch tank has a fair bit of oil in it and when idling it smokes/steams quite quickly.
the exhaust is also black and when i put a white rag next to it you can physically see lots of black dots appearing, either oil or fuel.
i'd like this to be a simple problem but i fear its not.
cheers

Think it might be a good idea to carry out a compression test ? Check valve clearances, do you know what cam it has as a modified cam may run different clearances? Look inside the distributor cap for tracking, looks like pencil lines . Also check the rotor arm as well . If you use a decent pair of insulated pliers you can pull a plug lead off one at a time to check for a decent spark at the plugs. It sounds like you are using multi carbs? if so check the jets on each carb as even a blocked jet will cause problems . Spray WD40 around the inlet manifold to cylinder head joint and also carb to manifold connections , an air leak will cause the engine revs to rise when sprayed. Try this lot, hope it sorts it out for you

Any tappet rattle? I once had a cam lobe on a pre-crossflow that suddenly went from OK to loosing about 5 mm and concave follower.

Found it by measuring lift and adjusting gap while running. Only quiet point was with zero gap !!!

A the valve is not open for long, oil can be sucked past the rings when like it.

Hope U fix it soon.

Keep us posted.

[Edited on 28/3/11 by avagolen]

its running a 234 kent cam
on electronic ignition so no dizzy.
did a compression test last week and was giving me 85.
cleaned the carb and the jets all seemed fine.
tryed spraying stuff in and around as well but no change either.
i wouldnt say there was tappet rattle, just the sound of all the vavles clicking away.
is it advisable to run the engine with the rocker cover off?
cheers

Did you do a compression test on all 4 cylinders?
If so i beleive they should all be within 10%

You can run the engine with the rocker cover off, but it will spray some oil about

Steve

yes all 4, the biggest was about 95.
is this about right?
its running a 1700 block, 1300 pistons and a 1600gt head with 234 cam.
cheers

That seems a bit low - comp ratio of less than 7:1 ????

possible worn rings then?

You did do the compression test with the throttle wide open ?

if not, it needs to be done again

Ah ok, will do it again.

I can't see why the throttle position would affect it?

Because you have a butterfly on each barrel of the carb strangling the engine!!

It is also a good idea to do a compression test 'dry' and then 'wet'.

Put some oil in the cylinders for the wet test - this helps to identify bad rings...

Len.