Head Job

The VC wasn't running too well - I suspected burnt valves and possibly other issues.

It was generally pretty untidy under the bonnet.  Compression readings were down on the front & rear cylinders and it was running very roughly at idle and only a little better when revved.  

Once the head was off I checked out the pistons & bores, which seemed okay - as far as can be seen without further dismantling.  The pistons were reasonably tight in the bores and there was no evidence of excessive wear or scoring.  There was a lot of oil down the bores, but this could be due to the sloppy valve guides rather than worn rings.

Unfortunately, no photo's of the head and its components (dunno what happened there ...), but once dismantled there were obvious signs of burning on the rear cyl exhaust valve.  The front cyl exhaust valve had receded right up into the port - not only was the seat badly worn, but the valve head had distorted to a bell shape.  This had caused the valve lifter to bottom out and there was no clearance (and thus no seal) on that valve. 

Paramount Engineering crack tested and surfaced the head.  They also supplied new exhaust valves with oversize heads, then re-cut the seats and K-Lined the guides.

As always, head bolt holes in the block deck are throughly cleaned by running a tap down them and blowing out - this is an extremely important step if you want the head to seal to the block properly - which you do.

Some of the bolt holes run through to the water jacket, so a sealant must be applied to the head bolt threads.

The head painted up nice and back in place - but when I fired it up the engine was still running on 3 cylinders.  "Dagnab it!", I said.

There was a lot of tappet (valve lifter) noise, so I suspected a collapsed lifter.  I removed the rocker cover and found the rear cylinder inlet rocker flopping loose and the pushrod riding a little low ...

Took off the side cover and discovered that the  lifter had spat out its innards.  Luckily, the pieces were still in the lifter case and - weirdly - the clip that holds the internal components of the lifter was still in place.  Spooky.

I checked out the cam lobe by peering down the lifter bore - looked fine.

You can see here the difference between the two types of wire retaining clip.  The one on the right is slightly thinner wire and doesn't hold the guts of the lifter in very well.  I replaced the collapsed lifter and another that had the same type of suspect clip in it.  A new pair of lifters was about $30.

Here's a photo of the guts of the two lifters, if you're interested.

Okay - take two.  It fired up immediately and ran like a champ.  "Oh, goody", I said.  Still a little smoke from the exhaust, so I guess those piston rings were a bit worn after all.







It takes a few seconds for this engine to build oil pressure on startup when cold.  This usually means main/BE bearing wear.  Not critical at this point, but I can see a bottom-end rebuild in this car's future.