Friday, January 6, 2017

Triumph Spitfire Engine Rebuild #5

Got a little bit of work done tonight...a Friday of all nights. Wife is going to sunny FL for a few days starting tomorrow so it's Daddy Daycare for a while. Perfect timing on her part as we are expecting 4-8" of snow starting right about the time she is supposed to take off. Since this is a family-oriented blog, I won't say anything.

I was able to source some rubber washers for the steering knuckle from my local True Value store. They are 1/4" beveled rubber washers and ran me a whopping $0.23 each. This is opposed to $1.96 from The Roadster Factory. This is not to disparage TRF, of course, as I've spent quite a bit of money with them in the past and have always liked the quality of their parts. In this case, however, the fit is too close to pass up.

The only modification requirement, however, is that the center hole is too small and must be drilled out. I forgot my drill index at the house so I wasn't able to drill out the rubber as large as I wanted. I was able to do a proof of concept with a too-small bit that I had laying around the garage, however, in the drill press and it worked just fine, so I don't expect any problem. I'll update with a bunch of pics when I get it done.

The washers, as bought. The screw is to the right. The washers at the top are just in case. Update forthcoming!

I did get a new toy in the mail from Amazon today. I fought with myself on whether to spend the money on a bore gauge since I don't really see more than limited use. But, since the workshop manual calls one out for measuring cylinder bores and I've seen them in all of the engine rebuild videos that I've watched on YouTube, I decided to drop the $55 on one. The Christmas gift certificate didn't hurt my decision, either! I went on the cheap side so I don't expect any miracles, but it should give me a warm fuzzy that the cylinder bores, and anything else that I use it for, are close enough. I didn't get to use it, but I will and I'll let you know.

The bore gauge. Definitely from China, but Harbor Freight doesn't carry them. Surprise!

The business end of the bore gauge. Instructions are in English, so there's that!

As I was going to meet the rest of the family for dinner (I got out of work early), I didn't really have much time to do anything else, but I wanted to get the core plugs out.

What are core plugs, you ask? They are commonly referred to as freeze plugs, but that is a misnomer. Based on the common name, many people believe that these plugs are there to provide a kind of over-pressure relief if the coolant in your block freezes. The idea is that these plugs will pop out as the water expands towards the freezing point to prevent the block from cracking. Well, that's not the case.

First, pure water expands as it approaches about 40F (4.4C), then it starts to contract. So, before it actually freezes, water is actually more dense than at freezing. It is a common misconception that water expands all the way to freezing. In any case, the plugs won't pop out. As much as a pain in the a$$ as it was to get my core plugs out, I can pretty much vouch for that fact.

What the core plugs are really for is a result of the casting process. Sand molds, or casts, were made for the cast-iron blocks. Since the molds needed to be designed to provide cooling jackets, oil passages and several other internal pathways, there was sand internal to the block that displaced the iron that was poured in. As a way to get the sand out, there was the need to have several holes in the casting. The block was designed so that the holes all fed into the same "side" of the block (the coolant side) and the sand was cleaned out through these holes.

Of course, the holes now needed to be plugged to prevent loss of coolant, so core plugs were used. At some point, I think during the Mk1 run, Triumph switched from a dished-type core plug to a bucket-type plug. The bucket ones are probably what you are used to seeing in most cars.

Dished-type plugs (except for that one just to the left of center, which is a bucket-type).

Bucket-type plugs.

I did specifically ask Rimmer Bros. just in case, but the dished and bucket types are not interchangeable. Since I didn't know the exact history of the engine, I ordered a set of core plugs for replacement. I did get them all out, but it was a struggle at first.

Most of the videos I watched were based on the much more common bucket-type plugs. The general rule here was to bang on one end and the plug would rotate in the hole, allowing you to pull it out. This, of course, didn't work for me.

Beat the heck out of it with no rotation. 

I finally decided to just punch a hole through the plug, then pry it out. Worked like a champ!

You can just see the hole at the top.

I made quick work of the rest of the plugs in a similar manner...

Just the hole.

The dirty result.

...except for the plug at the rear of the camshaft.

The rear camshaft plug.

I was concerned that I would damage the bearing face in the block if I drove a hole through this plug, so I used my 1/2" cheater bar to bang it out from front. I slid the cheater bar in through the camshaft holes until the end contacted the plug, then popped it out.

The plug is hidden to the far right. I banged from the far left. This is internal to the block; the red rags are in the cylinder bores.

Behind the removed plugs was not pretty and required quite a bit of clean up. There was definitely some adhesive or silicone of some sort in there and I cleaned this out as best I could. There was also quite a bit of normal carbon steel corrosion (black deposits) that was broken apart with a flat-end punch and light taps of a hammer.

Close up of removed plug above and to right of distributor mount.

Plug holes after cleaning them up a bit.

The gunk that came out of the above holes.

I realize the plugs are essentially dead ends for coolant flow, but I tried to clean up the internal areas as best I could. I'll do a flush way down the road when I'm actually ready to fill the thing will coolant.

I do want to mention that at all times I was concerned with what was behind the plugs. Since I had no reference, I couldn't be sure that I wasn't going to bash into something behind the core plug and mess up the block or a water jacket or whatever.

In the end, it wasn't a source for major concern. However, I did start by driving a pointed punch into the plug until just before it punctured it. Then, I went shallow on my angle quite a bit to just puncture through the plug, then pried it out with the punch. This would be a time when I kick myself for not doing a video. However, it worked every time.

This was the closest concern I had. About 1/2" from the plug face to a cylinder wall.

That was about it. I consumed copious amounts of Friday Night Pizza after that. I still have some core plug "socket" cleaning to do and I have to figure out the correct sealant to use (pretty sure it's just plain silicone), but I'm closer to painting the block. I ordered high temperature primer from Amazon as a base coat for my high temperature black paint. Not sure that this was entirely necessary, but at only about $6 a can (as an add-on item), I couldn't resist.


  1. "I couldn't resist." Best ending of a blog entry ever, and possibly the story of my (online shopping) life.

  2. I feel your pain, David. Pretty much the same for the bore gauge. The struggle is real!!