Oct 1, 2012 update to the Austin Mini Cooper S project car

Starting Our Mini’s Engine Rebuild

Jere Dotten studies the original engine that came with our Mini Cooper S.
The wrong head (above) has cheap, pressed rocker arms. The correct 1275 S head that came with our car has much nicer cast rockers and several other differences.
While looking everything over, Don Racine of Mini Mania confirmed that this was the proper transmission case for a Cooper S.

When restoring a car, normally we leave the engine and transmission together while we start on the bodywork. Then, later in the process, we’ll come back to the drivetrain. This time, things would be different.

When restoring a car, normally we leave the engine and transmission together while we start on the bodywork. Then, later in the process, we’ll come back to the drivetrain. This time, things would be different.

When we bought our 1967 Mini Cooper S, the engine and transmission had been completely disassembled for a rebuild 30 years ago. And that rebuild did not happen.

We figured that rather than disassemble the rest of the car, we’d be better off by assembling what had already been taken apart. Later, we can continue with the disassembly.

When we went through all the bags and boxes of parts, we found most of what we needed, including the correct numbers-matching block and head as well as the correct gearbox and differential for a 1967 Cooper S. Don Racine of Mini Mania checked out all these pieces and confirmed their correctness.

We also found the block was standard bore, but was worn about 0.006 inch over. We could have just bored it 0.010 or 0.020, but for some reason the project came with four new 0.040-over Hepolite pistons.

We discussed this dilemma with BMC A-series engine guru Dave Anton. Since the block needed to be bored, he suggested that we order a 0.040-inch overbore and use the $400 worth of pistons that came with the project. This would give it a bit more torque, too. Additionally, we’d be leaving some room to grow, too, as Anton says that these blocks can be overbored up to 0.060 inch.

It was an itsy bitsy, teeny-weeny rally-winning project Mini. Subscribe to Classic Motorsports and get it in your mailbox.
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Comments
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JB3
JB3 None
10/18/12 1:54 p.m.

I still have a '65 1275 Cooper S that has been sitting for 35+ years so I can't tell you how much I am looking forward to reading about your restoration. I raced numerous Minis in the mid to late 60's and then again mid 70's so it will bring back many memories of those great little cars. Jim Boehm

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