Cleaning the Slugs

Well the cleaning continues!  For those wondering about the title, slugs is another name for pistons.

I put the main bearing caps in a Simple Green solution a couple of days ago. Yesterday I gave them a bit of a brush to agitate the grime – they were really slimy and covered in thick greasy oil.  Today when I pulled them out they looked pretty good.  There is still a small amount of stuff on them, but I don’t need them to be medical grade.  I think the results are pretty good.

IMG_1951  IMG_1952

Next on the list were the pistons.  I have been thinking about these for a couple of days.

IMG_1955  IMG_1956 IMG_1957  IMG_1958

Simple Green attacks aluminium, so I decided to give them 5 mins in a Simple Green solution followed by a once over with a brass wire brush rotating slowly in a slow drill.  I concentrated on the flat sides of the pistons and the top mainly.  I then soaked them in gun wash for a couple of hours and did a little bit of brushing to help loosen the oily residue.

There is a groove at the top of the piston above the top ring groove.  I found that an old used hacksaw blade was exactly the right thickness to clean out this groove.  Because the blade was old it did not cut on the sides, and was not as sharp as a fresh one….perfect!  The groove was about 5 times as deep as I expected and was of course full of carbon.  Not sure what it is there for?

IMG_1959  IMG_1960

I then broke up one of the compression rings and used both ends (use the square end, not the end you have broken off) to clear out the top groove.  The second groove was clean, as was the oil control ring groove.

IMG_1954 IMG_1961

Speaking of the oil control rings, I found something unusual.  One ring had a different design spring behind the ring.  7 had solid springs, and one had slots in it.  Surely this wouldn’t have come from the factory?


Anyway, after cleaning out the grooves I soaked the pistons in gun wash for another 60 minutes and then pulled them out.  I can’t see any cracks which is good.  A couple of pistons have tiny dents in the top – maybe from a little bit of detonation?  One piston has a mark in it that looks like a valve has given it a kiss (see second picture below).  Overall they look to be in good physical condition 🙂

IMG_1968  IMG_1969 IMG_1970  IMG_1971

I could have chosen to try and make the pistons look like new, but the more you handle them, the more you risk dropping or damaging them.  I also didn’t want to go too hard with the brass wire brush, especially on the sides of the pistons.  The pistons are physically clean but not ‘medical grade’ clean.  More than adequate for a piece of lazy Detroit iron!

When I visited John Sidney Racing last week to drop off the block, they informed me that they did not have the correct size drift to press out the gudgeon pins.  They have given me the name of another old timer who should be able to help me out.

My daughter Gabby took many of the pictures today, and she added a selfie which I found on the camera, so you get a bonus!  She is the one on the left – Hagrid on the right.


Please feel free to comment below on my shenanigans, or even click on ‘Follow’.  It would be real nice to know who is out there watching!


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