Head swapped?

Hi again. Still having problems with the running.
I've fitted an engine in my 1.5 that was already rebuilt when I got it. It's a 1.5 JB engine same as my old one but getting it to idle smoothly is impossible. I now think it has a 1.6 head on. Is this a possibilty? How can I tell? Will it make a difference to the idle? it's an auto and when driving it's OK. Just stationary at idle in drive is a problem. Will a bigger idle jet in the weber carb make a difference? so many questions…….
Thanks

i wouldnt say the head makes a difference

idle issues are sometimes down to leaking air pipe have you replaced them, also what carb are you running?

Have a look at your carburettor flange too! They always perish and split! 

It's a weber 36TLP that was on the old engine. It ran beautifully on that one. Checked for air leaks and changed the gasket. my local garage has had it for a few days and he can't find anything wrong.

Tintop or cabriolet

It's a tintop. 1982 1.5 automatic. Auto's been serviced and the engine tuned up and checked over. The mechanic has tried all sorts but can't stop the shaking……and the car too!!

Still running points or have you gone electric ignition?

Does it idle ok when in neutral and the problem only happens when in drive or is it all the time? 

It's running with Powerspark electronic ignition and a new Powerspark coil. It is slightly lumpy in neutral but worse when drive is engaged. I just checked in the Haynes manual and the valve opening angles are different for 1.5 and 1.6 which may explain it. perhaps I'll to renovate my old head and put that back on.

The opening angle is done by the camshaft 

Just swop that over from your old head maybe 

Good idea. I'll sort it weekend. It's always helpful to have second opinions. Thanks.

if its a 1.6 gti head it will have holes in the back for the injectors.

the later 1.6 carb heads are totally different so i doubt its one of those. compression would be too low, big hole on the front for oil drain etc

a 1.6 gti cam would work better than a 1.5 carb one not worse

edit: the earlier 1.6 carb EM and FR head and cam is same as the same as the 1.5 JB according to ETKA, the EW head & cam comes back a different part number.