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S 6 : Ep 144

Enjoy 11275cc engine stories, opinion, and features from across the car world - Hagerty Media

Davin may not be Michael Caine zipping through Turin, but rebuilding this classic Austin Mini Cooper S brought him a few thrills. This little 1275cc engine from 1965 gave him a few headaches but that’s just par for the course when you’re constantly working on cars you aren’t completely familiar with. It just goes to prove that even the simple rebuilds can be frustrating and rewarding all at once.

This Mini rolled into the Redline garage running but still in need of serious attention. The exhaust pipe was more like a smoke machine, and in general everything under the hood could use a good cleaning. With the literal millions of 1275cc A-series engines on the road Davin had hopes that this rebuild would be a quick in and out job, but of course, the engine had other plans. During teardown, all the dirty secrets came out.

First was the gutted thermostat, which implied there were likely some overheating issues in this Mini’s recent history that someone tried to band-aid rather than fix. Then there was the two large gouges in the engine block that Davin found when the cylinder head was removed. There was no other real bad news, but when the issue at hand could require a new engine block it was obvious Davin and the team were holding their breath as they headed over to Thirlby machine shop to get the machine work done.

“The rest of the block and cylinder head were pretty good, but those gouges were pretty deep,” said Davin about the hand-wringing on if the block would be salvageable.”We got a little lucky in that while decking the block didn’t completely remove the damage it got it plenty flat enough for a gasket to take up the rest.”

Direct from the machine shop to the paint booth, a fresh coat of dark green was sprayed on the freshly machined parts and also a few of the sheet metal cover pieces. With the infamous self-peeling tape out of the way it was time to click off the torque wrench and get things put together. While noting the fact the oil pan was also the transmission case, Davin said, “Taking a lot of this apart was strange, but putting it back together was even weirder.”

Even with a few hiccups on finding just the right part, this Mini still didn’t turn into the maxi problem that it could have. The engine got its break-in and final setup in the wee-hours of Saturday morning and it won’t be long before the car rolls out of the Redline garage and over to the Hagerty Learning Garage for a complete restoration. Of course, Davin is not going to sit and twiddle his thumbs now, as he has other projects running and a new one currently in transit to the Shop. To see what that is and never miss an update, be sure to subscribe to the Hagerty YouTube channel.

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Enjoy 11275cc engine stories, opinion, and features from across the car world - Hagerty Media

These days, not much surprises Davin when it comes to events in the engine assembly room. Elements outside his control, however, can provide an entertaining change of pace. Take for instance the incorrect bearing size setback he discovered last week. His plan was to pivot to the transmission, but instead he got something unexpected. A surprise, but not such an unpleasant one.

The first set of bearings that were ordered ended up being too small for the finished machined crankshaft, but a replacement set arrived faster than expected and allowed progress to roll forward (almost) without a hiccup. We say “almost” because Davin might have had the proper bearings, but he lacked the proper tool to check the oil clearance on those bearings. Without micrometer that will do the job, he had to resort to a very basic tool that he doesn’t use often—Plastigauge.

“It’s not that Plastigauge is bad; it’s not,” said Davin about the measuring material. “It’s more that I find it to be a little inconsistent and I don’t have any way of confirming what it tells me with hard numbers.” No matter; it will have to do for this engine, since there is a bit of a deadline looming. Instructions for using this tool are simple: assemble the connecting rods to the crankshaft with a small piece of Plastigauge between the bearing cap and the crankshaft, torque everything down, then disassemble and use the Plastigauge package to determine the clearance. Davin first thought this engine to be a bit tight, but then he remembered that the journals on this crank are much smaller than he is used to.

With a few other parts already installed, the Mini engine is effectively sitting now at the short-block phase. The cylinder head is next, and if the rotating assembly was any indication that will come together quick. Or maybe there will be another odd hurdle? We don’t know, but regardless we will be back next week with another Redline Update. Be sure to subscribe to the Hagerty YouTube channel to never miss an oil-soaked minute.

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Enjoy 11275cc engine stories, opinion, and features from across the car world - Hagerty Media

The green paint on the Austin engine has dried and the infamous self-peeling tape has left the building, which means it’s assembly time for Davin. Of course, assembly is a lot more than just bolting things together, and this time around there are tips to be shared and lessons to be learned about why the engine assembly process is, well, a process.

The bare block is cleaned, painted, and ready for the fun part of installing the bottom end. Before Davin can go about pressing the cam bearings into place, he needs to reference the photos he took during disassembly. You hear him talk about taking reference photos before and during every rebuild, and it’s moments like this when they can make your life so much easier. The cam bearings have a few relief cuts and directional oil holes that need to be clocked correctly. A quick look at photos from disassembly makes the process fast.

Next up, it’s time to check the machine work. This isn’t Davin saying he doesn’t have faith in the team at the machine shop to do it correctly, but more of an assurance that once he starts putting pieces together everything will actually work. Bearings can be accidentally packaged wrong, measurements can be goofed, and if either one of those happens you want to know before you are trying to torque things down and wondering what happened. In this case, it comes down to confirming the rod bearings are incorrect. Davin was optimistic and ordered standard-sized bearings before dropping the crank off at the machine shop, where it was discovered that the rod journals would need to cut one size under after all.

That hiccup is not going to stop Davin from making progress though, and he pivots to installing the crank. Same process, measure the assembled bearings and fresh crankshaft to make sure that oil clearance is correct before slathering it all with assembly lube and torquing down the caps. It was also a quick projects to assemble the valves into the cylinder head before the roadblocks stacked up enough to hinder progress.

New bearings will be in shortly, so be sure to tune in next week to see the continued progress on this engine and the many other projects currently running in the Redline Garage.

— Kyle Smith

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Enjoy 11275cc engine stories, opinion, and features from across the car world - Hagerty Media

The engine for our 1965 Mini Cooper S may be bored, but we’ve never been more engaged. This week Davin heads over to Thirlby’s Machine Shop to get this 1275cc British rocket cleaned up and (nearly) back to its original shape. We had some concerns about what we unearthed last week on the block, but it’s up to the boys at Thirlby’s to diagnose the severity of the damage. Happily, luck proves to be on Davin’s side.

This may be the first time in a while that Davin doesn’t need a hoist to drop pieces off at the machine shop. Both the cylinder head and engine block are easily carried in by hand for the first step: cleaning. Each piece has pressed-in brass plugs that must be knocked out before both components are baked to remove the old paint and built-up grime. Rather than open up the cylinder head, though, Davin decides to simply tumble it, fearing he may not be able to replace the brass plugs with pipe plugs after cleaning.

Once the head and block are looking spiffy, it’s time to check for cracks. No cracks found means it’s time to start cutting iron. The cylinder head gets its valve guides knurled and machined to size before new valve seats are pressed in and cut. That’s the easy stuff, though—the block is the main worry. With a larger arsenal of measuring tools than Davin, the Thirlby crew takes a look and devises a plan that they think will save this block with no extra work.

The bore is cut to 40 thousandths of an inch larger, which removes a sizable portion of the two eroded sections of the deck. Next, that deck surface is machined flat. Just 14 thousandths of an inch is removed here, which succeeds in cleaning up the mess Davin found. That 14 thousandths is just over half of the 25 we had to play with, so this block should happily live on and could likely even be machined again in the future should the need arise.

Right out of the machine shop, the parts go into the paint booth. Some taping off and a thorough wipe-down with wax and grease remover preps the lot for a quick spray of dark green that Davin has mixed up to match the color he spied under the grease and grime of the block. Once the paint has cured, it’s back to the Redline Garage to begin final cleaning and assembly. Of course, there are a lot of interesting pieces and processes to talk about there, but you will have to tune in to future Redline Updates to see those. Until then, be sure to keep working on your own projects, and subscribe to the Hagerty YouTube channel to never miss an update.

Tag: 11275cc engine

Enjoy 11275cc engine stories, opinion, and features from across the car world - Hagerty Media

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