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S 6 : Ep 148

Enjoy Thirlby Machine Shop stories, opinion, and features from across the car world - Hagerty Media

It’s a new week, but it’s the same ol’ story in the Redline Garage. The Jeep 4.0-liter is torn down to a bare block, which means it’s time for a field trip to Thirlby machine shop. This block might represent the best starting point Davin has ever carried through the machine shop door. Of course, that doesn’t mean there’s any less work ahead for the team

“Everything was in really great shape,” said Davin after returning with the freshly machined parts. “We could have just honed it and thrown it back together. Just not worth it though. I mean, you’re already there.” What he’s getting at here is that the engine is already torn down, so there is no point putting off a job now that will only be harder later. The 150,000-mile block didn’t suffer oval-shaped cylinders or any other signs of terrible shape, but it still made sense to spend the few hundred dollars and give it the full machine shop treatment. From the deep clean to the decking and boring, this block is better than new.

There are other parts of the Jeep that need that same better-than-new treatment, and the flywheel is one of them. The starter engages a geared ring on the flywheel to start the engine, and the ring often wears out in just one spot. The reason has to do with the physics of how an engine stops when the ignition is turned off, and which cylinder ends up on the compression stroke to stop the rotation of the crankshaft. The ring gear here could just be flipped, but pressing on a new one that will last a long time is easy enough once we are already in there.

Next stop is the paint booth, but before the engine gets there Davin puts some color on the block along with some other parts on which he plans to do some clean-up work. Casting burrs and sharp edges can make even the nicest paint job look grungy—and when has Davin ever been one to cut corners?

It’s fast progress on this straight-six, so be sure to subscribe to the Hagerty YouTube channel to never miss an update.

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Enjoy Thirlby Machine Shop 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.

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Enjoy Thirlby Machine Shop stories, opinion, and features from across the car world - Hagerty Media

Though the chassis of the ’37 Ford race car is making progress, the Chrysler 440 V-8 that belongs between its frame rails has been languishing in a corner … until now. Davin tore the powerplant down a while ago and now the 440 is finally getting its day in the sun—or, at least, its day in the machine shop.

Before the massive hunk of iron can get dropped off for final cleaning and machining prep, Davin attends to the little things that separate the best engines from the rest. Any engine builder can chase marginal gains in horsepower; that’s not Davin’s goal. Rather, he’s cleaning up the casting flash to improve oil drain-back and to prevent any large chunks from breaking off and getting pumped through the bearings with the oil. The process takes a bit of time, but peace of mind rarely comes free.

The engine is then declared ready to go and hooked into the back of the ’46 Ford pickup for the short drive over to Thirlby’s machine shop. Typically this would be its final stop, but for this Chrysler, Thirlby is only the initial destination. The cleaning will take place here; final assembly and dyno testing will occur at Apex Tuning. However, first the block needs to be preserved a bit to ensure that all the work done to clean it up is not wasted.

The first step is to oil down the block. Thanks to modern aerosols, this is an easy step and keeps the block from becoming a rusty mess after a few days of sitting in a plastic bag in the corner of the shop. If you’re also at this step with your own engine project, don’t be shy: This oil should be seen as an investment. Right before the block is machined, Davin will wash it all down and then the chips can fly to make way for new, oversized pistons. That’s for a later episode, though, so be sure to subscribe to the Hagerty YouTube channel to catch the episode as soon as it goes live.

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Enjoy Thirlby Machine Shop stories, opinion, and features from across the car world - Hagerty Media

The engines that come into the Redline Rebuild garage have run the gamut. Volkswagen flat-fours in boxes and bins, running Chevrolet big-blocks, and stuck-solid Buicks have each presented their own challenges, but the latest project was a luxury. at least, it came from a luxury car.

This Cadillac 365 V-8 was not the worst project Davin and the Redline Rebuild crew has taken on. It might actually be one of the nicer ones. It was a smooth running, albeit quite tired, engine from a driving car. That didn’t guarantee a smooth rebuild process though. From the first turn of a wrench there were questions and concerns about parts, but the crew got lucky.

“I was nervous about the availability of pistons and rings after hearing from a supplier that it had recently sold off virtually all its stockpile for these engines,” Davin says about the parts concerns. “Luckily, we were able to source what we needed quite easily, and all the parts played together nicely.”

It’s easy to say the parts went together well, but the reality is there was more than a little extra work on Davin’s side than just bolting everything together. That’s the nature of engine building—not assembling. You could just bolt it all together, but the engine would not perform like it could or should. Properly fitting each and every piece means this Cadillac engine will be smooth and reliable when it returns to the four-door cruiser that it was pulled from.

The 4-inch bore block was in great shape once everything was removed, so basic degreasing and clean-up machine work were all that was needed from the experts at Thirlby Machine Shop. The rotating assembly was in similar shape, but Davin elected for new pistons, which required heating up the connecting rods and pushing the piston wrist pins through for the perfect press-fit. The cylinder heads got fresh valve guides and seats pressed in before returning to the garage for the final assembly.

The coat of Royal Blue paint really dressed up the package and made the assembly that much more rewarding to watch. It’s a stock rebuild without any crazy changes, but ask any engine builder about the first moments of startup and they’ll tell you they’re always nervous.

Davin admits “it’s not the scariest thing, but I always have at least a small amount of concern on first start of a flat-tappet cam engine like this one” referring to the style of lifters and how they engage with the camshaft. For flat-tappet engines, it is best for them to start up with minimal cranking and very quickly get to around 2000 rpm to start breaking in the lifters and make sure the lifters do not “wipe” or flatten a lobe on the camshaft. With modern assembly lubes and break-in oils, this is not as high risk as decades ago, but it still happens from time to time. Luckily, it didn’t happen to Davin this time—but that doesn’t mean there wasn’t an issue with that first start.

Davin admits to checking and double checking the distributor timing, but on that first turn of the starter, a fireball from the carb confirmed that despite the careful check it was still 180 degrees off. Easy correction, and the next turn of the keys brought the humble Caddy to life and started the break-in process. It’s a sweet sounding engine and will sound even better once reinstalled its four-door home.

Another successful rebuild in the books, but there is no rest for the weary, and plenty of other projects are underway in the Redline Rebuild garage. Be sure to subscribe to the Hagerty YouTube channel so you never miss an oil-soaked minute.

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Enjoy Thirlby Machine Shop stories, opinion, and features from across the car world - Hagerty Media

In the latest Redline Update, Davin gets us up to speed on the Cadillac 365 V-8 and Honda Trail 70 projects.

First off, he inventories the Cadillac parts that remain after he disassembled the mill. The lifters show varying levels of wear, with the worst offenders displaying significant dishing. Those won’t be reused. New parts will join the original camshaft, which is being reground. Davin was surprised to find a new water pump; the big casting is pretty complicated, so it’s good to know that the cooling system will benefit from fresh components.

Plenty of the original Cadillac parts will be put back in service, however, and Davin reviews some of the steps used to restore them. For example, the V-8’s pushrods went through the parts washer and then through a tumbler filled with solvent and stainless rods to remove the baked-on oil. Now, they look brand-new. The rocker shaft assembly shows what the valvetrain parts looked like before that treatment. The shaft and its components are going into the ultrasonic cleaner before it heads to the tumbler. Due to the wear on the rocker tips, the rockers will need further work, since the ridges left by the valve stems need to be ground smooth.

Besides the tumbler and other parts washers, Davin and the Redline Rebuild crew rely on a media blaster. A quick trip to that part of the shop shows the valve covers getting stripped and readied for the same paint that will eventually coat them and the rest of the engine.

On to the Honda Trail 70, Davin lists all the new parts that he’s already collected, including clutch plates and a rebuild kit for the stator, plus brake shoes, sprockets, a battery, and an OE chrome engine guard. More and more original parts are going into the bin that’s destined for Jason’s Chrome, which will re-plate all those components in addition to polishing all the aluminum bits, including the intake manifold. Other aluminum parts, like the side case, will be sandblasted and Cerakoted. We also get a peek at the stamped steel frame, which is stripped of its stickers and nearly ready for sandblasting. The rusty split rims are also ready to get sandblasted. If they’re not too pitted, they’ll be powder-coated, but Davin’s lined up replacements just in case.

Next, the video team heads to Thirlby Machine Shop, where the heads get disassembled before being thoroughly cleaned along with the block. As previously discovered, one of the exhaust manifolds is cracked from the center port almost all the way to the collector; Davin plans to drill out the crack and weld up the cast iron. Luckily, the block passes its magnetic crack check with flying colors. Mike at Thirlby will handle boring, honing, and decking the block, making sure to leave the stamping on the deck surface intact. Compared to some of the other projects Davin has brought him, this Cadillac should be a cakewalk.

Finally, Davin reconditions the stock rods by pressing in new bolts, cleaning up the rod caps, and resizing the big end. As parts continue to show up, including the pistons and back-ordered fuel-pump rebuild kit, we’ll continue to bring you progress reports. Make sure you’re subscribed to Hagerty’s YouTube channel so you don’t miss a single one.

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Enjoy Thirlby Machine Shop stories, opinion, and features from across the car world - Hagerty Media

Grease and grime are staples of the Redline Rebuild garage, but this week is all about cleaning up. No, not the shop, but the Cadillac 365 V-8 that Davin tore down last week. This sturdy iron block is shaping up to be Davin’s main project and it’s time to fire up the parts washer.

“This engine is going back to bone-stock, unlike a lot of the other builds we have done,” says Davin. “Not that we couldn’t add a few subtle hot rod parts … it’s just that, in this case, that approach doesn’t make much sense, because the engine’s going back into a bone-stock four-door cruiser. Stock is best here.”

The mess of parts on the workbench has to be cleaned before the process can move ahead much further, and, for this step, Davin is happy to have his monster parts washer. All the bits and pieces that need to go to the machine shop get a quick bath to remove the worst of the grime before they’re loaded into the bed of the 1950 Chevrolet for a trip across town, where they are unloaded and placed in the waiting line at Thirlby machine shop.

The next step is machine work—sort of. Since both Thirlby’s facing a backlog of work, Davin shifts his focus to even more cleaning. He gathers all small parts that he’ll send out for paint, powdercoat, or CeraKote and begins washing and sandblasting like a madman.

Be sure to tune in next week to see whether Davin finds good news under all that oil and dirt. All the progress will be documented in upcoming Redline Updates, so be sure to subscribe to Hagerty’s YouTube channel to next miss a greasy minute.

Tag: Thirlby Machine Shop

Enjoy Thirlby Machine Shop stories, opinion, and features from across the car world - Hagerty Media

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