I’d have to say that Jag XK’s are right near the top of my favorite old sports cars from the UK. Probably a XK140 roadster would top that list just because they look the best to me, however for sheer brute strength it would be the XK150 S.
The 150 S had three 2″ HD8 SU carbs on long individual intake manifolds and the 9:1 high compression hemi- head. Some were 3.4 Liter displacement and some were 3.8L All had 4 wheel disc brakes, a first for Jaguar cars.
Here is a bevy of XK 150’s in front of my shop, the red ‘S’ roadster, a black 150 ‘drop-head’ or convertible in US parlance, and a white ‘fixed head’ or coupe if you like.
Customers Jags-3 XK150’s on the same day!
( Click once or twice on pixs to enlarge)
The black DHC is one I am just finishing up a multi-year restoration on. Perhaps I’ll finish documenting it in the future. Today’s entry however regards the red roadster and its mechanical ills.
The car presented with a lack of power and a lot (!) of valve tappet racket. These engines are of twin overhead cam shafts which act directly on the valve stems with an inverted bucket, the lash (valve clearance) adjusted via variable thickness shims or discs between the bucket and valve stem.
Visual inspection after removing the cam cover (exhaust side-where the noise was) showed nothing and compression reading were within normal expected at cranking speed. Now, its not too uncommon for the exhaust side to have the sleeve that the buckets reside within to move from their factory interference fit depth setting. Clever aftermarket plates are sold to sit on the vertical exposed face of the sleeves to hold them stationary in the head. So, I ordered a kit and installed it, but it made no difference in the racket. Sigh.
Bucket sleeve hold down plates
The picture above is after the head was removed. Since the hold downs didn’t fix the problem, I informed the owner that the head would have to be removed to see what was going on. I ought to buy a boroscope , but even then the head still has to be pulled to repair it. These triple carb cars require quite a bit more time to take apart as the inner engine compartment panels have to be removed and the fuel system piping and filters are a nightmare.. Try counting all the nuts that were removed, polished and replaced!
Well to make a long story short, the offending cylinder/valve was a wallowed out valve guide and do I mean wallowed out. Here’s a picture. Compare the guide diameters..
The guide in the middle is nearly half again the size of the adjacent guides.
As it turned out all the exhaust seats, guides and valves were replaced. I also installed new intake guides and 2 intake valves, did a 3 angle valve job and resurfaced the head. might as well do it right when its apart.
From the picture below its also clear to see that the cosmetic condition was rough and the customer requested that the entire engine compartment be detailed as best as possible with out removing the engine and other major assemblies.
A rough idea of the “before” picture
As you can see there was a lot of corrosion/oxidation on all the aluminum and the paint was badly degraded and the block was painted a GM orange at some point in the cars past. UGH!
So the customer wanted everything polished and painted..which meant dis-assembly and rebuild of the carbs and manifolds…
One of the big SU’s and the aux. cold start “carb” and piping.
After nearly a full day of standing in front of the polishing wheel, here are some of the finished bits..
Still have the carburetors to polish..
here’s the area prepped for repainting parts of the firewall and radiator surround..
Takes longer to mask than to squirt some paint…
And finally here is what it looks like now…
More than a couple hours of work..believe me!
So after restoring the air filter assembly and painting the under side of the hood (bonnet) it was looking damn nice and needless to say the car ran like a scalded cat.
Cost? More than the customer wanted to hear, but it was what he’d asked for and he did get some frequent flyer points from his credit card company.. :~)
Dave
No comments yet.