Engine Rebuild: Honing and Piston Rings

I’ve been taking my time rebuilding Studebaker’s small block Chevy, some of you may be wondering if I’ll ever get finished. After Phase Two’s revelation that my 383-stroker is in fact just an over-bored 350, I had to stop and do a little soul-searching…would I continue putting it back together pretending it was a 383 or would I stop and make adjustments as needed.

What I’m referring to here is something which I already had an inkling was negatively affecting my engine, for the street-driving purposes I use it for – namely, my Team-G high-rise single-plane manifold and my Holley Street Avenger 770 cfm carburetor. If you’re anything like me (still learning!) those two things may not raise any red flags in your mind – but as I’m finding out, they have a HUGE affect on my engine.

In it’s most rudimentary sense, an internal combustion engine is fuel+air+spark=power. My single-plane manifold and 770 cfm carburetor both mean there’s a lot of air trying to be fed into my engine. I’ll talk about this in more detail in a coming article, but lets suffice it to say for now that all that extra air isn’t a good thing! I’ve decided to switch out my intake manifold and carburetor and am really excited about the changes these new parts will make (I’ll share more about this and my new parts in my next article).

While I was making that decision and waiting on parts, I had a few last things to do before I was ready to start putting everything back together – removing and inspecting the cam, honing out the cylinders, and replacing the piston rings.

Honing the Cylinder

Boring your cylinders is something to have a machinist do, honing is a minimal surfacing of the inner cylinder walls that can be done at home. The purpose being getting off the layer of muck on the inside of the cylinders and giving them a nice surface again. Because the shape of your engine’s cylinders is extremely important (remember the detail in using a micrometer to measure them?), you can’t just do this job with your hand and a piece of sandpaper… special honing tools must be used.

While Ethan prefers to use the ball-type honing tool for its nice resulting crosshatch pattern, they go for roughly $100 and we don’t have one in our tool collection yet – so instead we used the basic adjustable hone, borrowed from a friend. You attach the honing tool to a drill and carefully run it down and then up again inside each engine cylinder. After doing this the block needs to be thoroughly cleaned, you don’t want any stray metal shaving left in your block!

From there I was almost ready to put everything back together. I still had to do the final cleaning and painting of my engine heads, harmonic balancer, and water pump. The pump was a new one, they’re inexpensive and having everything apart is an easy time to replace it. I had already taken my heads to the machine shop – getting them resurfaced (decked) and checked for wear. I was sure to be extremely careful with the head mating surface after that and thoroughly taped it before painting. Old spark plugs make perfect hole fillers when painting heads! I had one more thing to complete before being ready to put it all back together (are you thinking of Humpty Dumpty too?!)

The piston and main bearings both showed some wear, so those were replaced as the video goes over in the last post. The piston rings also were being replaced…

Replacing Piston Rings and Bearings

Piston rings sit within recesses in your piston’s sidewall and are basically compressed against the cylinder wall. They’re responsible for keeping oil and/or air from blowing by (remember that the cylinder is where the combustion happens, so it needs to be tightly sealed off!). Over-time piston rings can wear out, loosing some of their tension. Other than just being a handy time to get at these parts, the fact that a couple of my cylinders had decreased compression indicates that it’s a good idea to change them.

A piston ring tool helps take them off and put them on. You can see how simple it is in the above video.

After I got them all off, I used another specialized tool to clean out the recessed area.

After giving each a good cleaning it was time to put the rings back on. As you don’t want to snap any rings during the process, some care needs to be taken to not twist or bend the rings too much (I didn’t have any trouble while I did it). As you can see above, each ring needs to go in a specific place. You’ve compression rings in the top two grooves and then an oil control ring that is sandwiched in between two “rail” rings in the third groove.

Don’t forget, you need to keep all the pistons in order during this entire process – each piston, lifter, rod, and rocker arm needs to go in the same cylinder that it came out of. Even though I had taken every measure to keep things in place, I’ve still been terrified during this entire process of something getting out of place! If our garage was a bit more orderly and we secured everything on a protected shelf somewhere, I would’ve felt much better about it.

Now that my block is ready to go, my pistons are ready to go, I’ve replaced the bearings and have my new parts and gaskets…I’m finally ready to start putting this ol’ girl back together again!