For months I've had a bit of an intermittent rough idle, and this slight
miss at idle made it difficult to pass emissions due to high
hydrocarbons.  I've tried everything to solve this, which is typically
caused by a vacuum leak.  This engine is new, and I had the problem
before installing it.  Every hose was replaced, and everything checked
out EXCEPT for two things.

Drum roll please . . .

Air was leaking into the crankcase (and getting sucked into the intake
manifold as unmeasured air though the crankcase ventilation system)
around a hardened dipstick stopper and also around the joint between the
plastic extension and metal oil fill tube!  Grasping at straws I put a
rubber stopper in the dipstick tube and a hose clamp around the filler
neck (it was loose, I should have guessed this was a problem). Voila,
smooth idle!  I'm not going to pay for another emissions test, but I'll
bet the HC reading is much lower now that the miss is gone!

As the years go on for these vehicles the problems become more obscure!
--
Stuart MacMillan
Seattle

'84 Vanagon Westfalia w/2.1
'65 MGB (Daily driver since 1969)
'74 MGB GT (Restoring sloooowly)

Assisting on Restoration (and spending OPM):
'72 MGB GT (Daughter's)
'64 MGB (Son's)

Stripped and gone but their parts live on:
'68 MGB, '73 MGB, '67 MGB GT