Tales of The Engine Room

John prepares for a road test

Goggles not really optional

While not strictly a picture from this week, it’s actually around October 1st, it is a pretty accurate snapshot of how things usually are.  John is about to run off a couple of (very) quick miles in this Shorrock supercharged MG TC.  Both he and I possess a proper set of racing goggles because every so often you need ’em.  The Brooklands Racing ‘Screens might look the part, but they’re really not.

Directly behind Butch is the just-tested Austin Healey BN7 two seater, and behind him in the shop is a glimpse of Morgan.

Setting Jaguar valve clearances

Setting Jaguar valve clearances

Chris and I have been downstairs thrashing with Jaguars.  He’s just about the twist the key and run up the XJ6 which suffered a piston failure caused by a valve failure.  Meanwhile, your scribe set the valve lash on a Series 1.5 E-type cylinder head on the bench yesterday, the rest of the engine (not seen) is on the stand behind him.  When setting Jaguar valve clearances it’s important to do one side at a time, intake first, then exhaust, or vice-versa.

Close examination will reveal that all of the intake cam bearing caps are completely loose.  This is to prevent a potential collision between fully open intake & exhaust valves.  It’s a hemi, remember, and they need to take turns opening and closing.

Damaged Jaguar cylinder head


Repaired cylinder head


This is the before and after of the XJ6 cylinder head.  There was a mighty collision between #2 piston and its exhaust valve.  The exhaust valve stems were heavily carboned up, probably due to excessive valve to guide clearance, and that, we believe, hung the valve open long enough for the piston to hit it.

Broken piston with valve

The piston with its assailant

The cylinder head on the left, and the cylinder head on the right are in fact the same cylinder head, but how we pulled that off is a proprietary secret.  Suffice it to say we have very deep resources and we’re good at this stuff.

And although it isn’t obvious, it’s also a  2nd hand set of valves.

This is the aftermath.  What we have here are a couple of expensive paperweights.

A wrist pin clamp bolt with the threads stripped

The failure that didn't happen

Today’s final exhibit is an engine failure that didn’t happen.  This is an MGA wrist pin bolt with the threads stripped by bad assembly work.  The small end of the connecting rod is slotted, and the bolt, which locates thru a relief on the wrist pin, draws the slot closed around the pin.  We ALWAYS start these by hand, but this installer didn’t and ground the threads off, most likely on the edge of the relief.
More on this in a few weeks.

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