3 1/2 Derby Engine Block problem

[Arthur Farrow]

My first post be gentle with me!!

Shortly after I bought my Derby from a dealer whose only attribute is flash trousers I noticed an odd mark on the block below the carbs. It turned out to be a bodge and gradually over the past 3 years a plastic filler scab grew out from the block probably pushed by rust inside despite Mr Evans cooling fluids (what is that stuff?) and now of course its leaking badly. This is a real shame as the car runs lovely.

I'm really a Motorcycle man and can rebuild a Vincent or Morini engine before breakfast, but the Derby is beyond my workshop facilities. A motor engineer friend whose father is getting bored in retirement has offered to sort it and is talented enough to do so, but with no experience of these engines so I have a few questions please.

Getting the bonnet & head off will present no problem, but when its off

1. Is the sump easily removable to get at the big ends or is it engine out?
2. Is a 31/2 block interchangeable with the 4 1/4 block ?. I know the stroke is the same
3 Quite what we will do with the block when it is off remains to be seen. Any advice or recommendation - or does anybody have a nice block and pistons taking up too much space that might be available for some £s?

I'm sure there will be many many more questions and thanks in advance for replies

Arthur

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[Christopher Carnley]

The sump (crankcase lower half) is removable, but it is not "easy".
Note the bolts and double nutted studs securing the oil pump and distributor drive on the front o/s corner.

The block silt / stone chokes up and the 37 copper tubes have to be removed to clear it. Then the new tubes have to be swaged in.
A long, painful,shocking,job.

The blocks are not interchangeable.

I know a guy who has a good block and head pair of 3 1/2 litre parts, but they are choked, and hard choked at that.

So if you P.M. me, I may persuade him to talk to you, but it will be a couple of K each for either part !


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People wonder why I will not recommend anyone buy these heartbreak cars.

[Christopher Carnley]

The site is picture dysfunctional.

[Stephen Blakey]

If the car is running well, it does seem a shame to dismantle it and to undergo the very comprehensive wallet emptying procedures which will inevitably follow.

Could you get a few more seasons out of this block with a stainless steel or brass patch screwed and epoxied over the hole? There was a time when no one would have batted an eyelid at such an approach.

I did take a block to Slinden's to have a crack stitched (on behalf of a fellow BDC member). On that occasion the large bill was justified by the amount of work that had already been done to it, otherwise it wouldn't have made much financial sense.

For completeness, Slindens did say they could do the job in situ, however it wasn't possible on that occasion as the steering box was in the way. I took them the engine complete and I'm pretty certain it remained complete throughout the procedure. The repair oozes a bit.