Engine re-reassembly.

Time to reassemble the engine, and this time I’m being super paranoid. So I took photos.

First it gets a damn good clean with degreaser and brushes and rags on sticks and a lot of compressed air. And then I wipe it down with a clean paper towel to make sure it’s not still dirty. Obsessive-compulsives would be proud. Or uncomfortable.

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I checked the fit of the followers by measuring the bores (all perfect), then dropping the followers in dry (they all fell in easily with a solid “click”)

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Then we assemble with engine assembly lube (decent Torco brand stuff)

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A decent dollop of engine assembly paste (Moly paste) to help the nice new lifters bed in.

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…and more moly paste on the cam once it’s installed.

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Drop engine into car (Attempt #1 pictured. Not pictured: attempts #2-#27, swearing, sweating, or bleeding.)…

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…and test drive. Bursting the oil cooler is optional, but thoroughly recommended. Such fun. Aargh.

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New cam followers

The new, correctly-ground cam followers arrived from Keith at Calver Special Tuning. Unsurprisingly, they’re exactly right at c.75″, and all absolutely identical.

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I photographed each one as I measured it, but they’re all the same so there’s hardly any point in posting the pictures.

Just a reminder: the old followers (with 500km of use) measured all over the place. When Minispares sends me a new set* I’ll measure them and see how they compare.

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*Since the old ones are clearly defective, I’m confident that Minispares will send me a replacement set. Yeah right.

How to measure cam follower face radius. Sort of.

The cam followers have piqued my interest- the suppliers say the face radius is probably ok, but won’t tell me what “ok” means, because it’s a trade secret.

Given that it’s a trade secret for followers that have been made since 1995, I found out* that the radius should be between 52 and 81 inches, (ideal is allegedly 72-74″) which equates to 0.0012″ – 0.0007″ height difference between the centre of the follower and points 0.70″ apart. Not easy to measure accurately, but not impossible to measure with the right equipment.

Let’s make a thing!
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The block was drilled and tapped on the bench drill, using the drill vise, so the holes are parallel and in line. The follower specs call for measuring face drop at 0.700″ diameter, so that’s how far apart the threaded holes are.

Next we screw the pointed probes into the block with a bit of thread lock to keep them aligned, making sure they’re exactly the same length.

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And there you have it. A DIY spherometer.

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Using it is a little tricky- to get repeatable results, you need to make sure the gauge is perpendicular to the surface being measured- I just held it against a square. Zero the gauge on a piece of mirror:

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…and start measuring.

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I measured each follower twice at right angles, then checked that the gauge was still zeroing on the mirror surface. I measured the entire set twice too, so each follower was measured four times. The measurements and zeroing were absolutely repeatable (except for the follower which had its face ground non-perpendicular to the sides. Seriously, WTF?) – and repeatability is SCIENCE.

Just for reassurance, I measured a bunch of cylindrical and spherical things of known radius- and it turns out my little gauge is eerily accurate. I didn’t have anything as large as 80″ to measure, but it was spot on at 30″.

Now is the time on Sprockets when we math:

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Easy peasy. I won’t subject you to the math, but the results were that 2 of our followers were about right at c.70″, three were a bit low at around 85″, two were at c.114″, and one was around 150″.

The reason I wanted to measure the followers is because it’ll cost $20 to post them back to the UK, and the supplier has a vested interest in saying “they’re fine, nothing wrong with them”. But since they’re definitely not right, I’m a bit more confident about spending the money now.

*It’s not what you ask, but who you ask. Though I’m not going to name any names, just to be on the safe side.

Engine revision progress

Well, I’ve replaced the old brass plug with a new steel one and had it surfaced- a lovely repair, if I do say so myself, I just wish I’d done it the first time around.

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I’ve dismantled the clutch, and it was pretty filthy with oil. Add one new clutch plate to the parts order.

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There was a bit of burning on the pressure plate too- possibly it was working harder since the flywheel side was all slippery?

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Keith Calver reckons my cam is probably salvageable, and has a put a set of his correctly reground followers in the post.

Everything else is ready to go, now it’s just a matter of being patient until all the new parts (followers, gaskets, clutch plate) arrive.

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It’s not a car, it’s a hobby. It’s not a car, it’s a hobby. It’s not….

The last time we had the head off we noticed that one of the brass blanking plugs was moving, and would need to be fixed soon. And then a few days ago we heard a bit of a rattle from the drop gears- so it seemed like the perfect time to pull the engine and check it out.

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There have been one or two unpleasant surprises. Like the oil leaking past the primary gear and onto the clutch:

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We know it’s getting past the primary gear because the main seal is spotless:

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Turns out the brand new primary gear we bought from Minispares has 0.006″ clearance on the front bush when it should be 0.004″ to match the rear bush. I guess it explains the drop gear rattle. It looks like the odd clearances caused the gear to tilt while running, overheating the front edge of the bush as well as allowing oil past. It’s the one on the right:

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Fortunately we have a spare primary gear which has good clearances all round, so that’ll be going in after polishing the crank bearing surfaces.

While we were in there, I decided to check the cam and followers. I’d come across a few articles* and forum posts lamenting the quality of cam followers produced since c.2011, and since we bought our followers in 2012 I wanted to check that all was well.

All was not well. This is what a cam lobe and follower should look like:

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Note the lobe wear on one side, and the circular wear on the follower. This indicates that the lobe is touching the convex radius on the follower face correctly, and that the follower is rotating properly. Only half of our cam lobes looked like this- and this one was the best.

Here’s what the other four looked like:

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Cam wear in the centre of the lobe indicates a flat faced follower, and the back and forth scuff marks on the follower face clearly show that it isn’t rotating much.

Since we’ve only done 500km I’m really, *really* hoping that the cam can be salvaged by fitting new followers, otherwise we’ll need to buy a new $400 cam as well as the $100 followers.

Aargh.

Oh, and the head plug that’s moving? Fairly common, it turns out, and the repair is straightforward. Here’s the plug, it should be flush with the head surface but this one’s started to move back into the head about 0.2mm. Since it intersects the fire ring of the head gasket it needs to be fixed.

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Simply tap the plug, and extract it using a stack of washers:

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Then tap the hole to 3/8NPT, install a solid pipe plug with a bit of retaining compound for luck, and machine it flat again. Which I’ll do once I find my 3/8NPT tap.

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*The best articles are at Calverst.com and Russellengineering.com.au