Tuesday, January 25, 2011

Things to avoid doing when you are building motors

My dad tore down a 51 panhead motor today and it was filled with poor workman ship. It must have been put together by some hack in his garage. Anyways, I took some pics of the blatantly obvious substandard repairs so I could show you guys what not to do in your motors. The tapers for the crankpin in the flywheel were worn out, so the flywheels were too close together and consequently the rods did not have enough endplay. It looks like some bozo ground the sides of the rods with a makita grinder. If you click on this picture and zoom in, you can see the few spots where it was still touching the flywheel thrust washers! what a hack job. These rods are s and s rods and are too heavy anyways, so we will end up replacing them with something that is closer to the same weight as oem rods.

NEVER use silicone on anything. IT is the worst sealant of all time. It was invented by the devil to clog up your oil pumps. This is very hard to clean, but can be fixed. You guys will save yourself a lot of heartache if you throw away any existing silicone tubes that you have and use good sealer.

I think that the theory behind putting this fitting in, was to cross thread it so that it wouldn't vibrate loose. what a joke.


  1. Ben Edwards in Charlotte was showing me a set of knuckle pistons that had plates welded below the rings on both the front thrust side and the rear side, both pistons. And it was running....smoking but running. I'll see if the owner let him have them and if he did I'll email you a photo or two. It is amazing what some of these motors (and bikes) have been through!

  2. Hey Matt, what sealers do you recommend? I have used the harley grey sealer for most stuff, and that copper spray-on stuff for smaller/paper gaskets, and the white permatex brush-on stuff for any fittings that need sealing.

  3. Hi Lonnie,
    I would love to see the pics. I have some neat pictures weird things we have seen in motors that I should post.

    We use gaskasinch on oil pumps. Number 2 permatex on fittings,3m 800 on knucklehead top ends and pan cover gaskets, yamabond on cases and weather strip adhesive to glue felts into the top of panheads.

  4. Must have been the same hack that worked on an engine I am doing. Great description in that it looks like a makita grinder, that is how I described what I seen on a set of Indian rods!

  5. Man I almost threw up when I saw that cross threaded fitting on that oil pump cover..keep posting these atrocities when you come across them Matt, they are like a car crash that you can't help but look at LOL!!!

  6. I'm wondering what was used on the Sears when it first went together. Also I heard once of a Plymouth flathead 6 that was running with leather for bearing material. Heheheh. Cheap thrillz.