Engine Overhaul: Painting the Case and Cylinders

As a reminder, this is the color scheme i am going for on the engine:

As such, i started the final part of the painting process with masking of the case. As always, i sought some advice from the VAF Brains Trust who cleared up my understanding of what had to be masked. 

Basically, any place where there is a pad for an accessory, cylinder locations, any place somehting screws onto the case (such as a dipstick tube or oil pressure regulator), and finally, anywhere there is a fastener. 

Left Hand Case Masking

LHS case

The bottom left is the sump, and bottom right is where the starter will mount. This is important as the starter gets its ground through the mounting base.

We mounted the accessory case at the shop when the case halves were together, and traced the outline. I then masked up to that outline. I also masked off the mounting ears for the case. The white dot on the left is a location for grounding the case.

All the case hardware locations are masked here, as well as the holes for the pushrod tubes. These don't get masked on the top of the boss, but just on the insides where the pushrod tubes push in.

The cylinders and prop governor mounting pads were masked. I put a cylinder in place and traced around it.

The front of the case can be painted, but not on the inside where the seal will go. 

The screw aft of the prop governor mounting pad was put in the hole with tape around it - this is a hole into the oil gallery. I didn't have the correct sized plug for this location.

Screw holes got a 1/4-20 screw in place to stop the paint getting in. The ends of the fixed studs were left open, so the ends of the studs get painted. (i didn't paint the end of the cylinder studs).

Pushrod holes were just masked on the inside.

On the end of the left case is a port into the oil gallery - i had a correctly sized plug for this (i think it was 1/8" NPT) so installed this with thread sealant. 

Right Hand Case Masking

RHS case

The front lower pad was masked as this is the alternator location - it needs to ground through the case. The aft pad was left open to be painted, as i will not be mounting anything there.

Cylinders

Next up was the masking of the cylinders. 

The ends of the exhaust studs, as well as the rocker shaft cover studs were left open to get some paint.

I used old rocker cover plates instead of masking and spaced the nuts with washers, so only the ends of the studs got paint.

The cylinder heads were masked off totally, as i will be painting the barrels a different color to the heads.

Painting

Each part was painted with VHT engine enamel primer, then i waited 30 mins. Then painted the color coats. Either black for the barrels, Aluminium (silver) and then anodised blue for the cases, or silver for the cylinder heads. Then another 30 mins wait, then clear coat was also sprayed on everything. 

I already have a nice spray booth setup (OMG this was build 7 years ago), and i put the family lazy susan into service. 

I made a little jig to securily hold the cylinders. 

Primer

Gloss Black & Clear

Primer

Aluminium (Silver)

Anodised Blue / Clear

Primer

Aluminium (Silver)

Anodised Blue / Clear

The next day the barrels were sufficiently dry that i could mask the barrels off without damaging the paint. These were painted upside down, then flipped and done right way up. I found this was the best way to get both sides of all those fins. 

Here you can see a cylinder which had been painted upside down only. When viewed from above, it's clear the paint is only on the lower fin surfaces.

The same cylinder at the same point when viewed from below!

Primer only

Aluminium (Silver) & Clear

Removing all the masking

I found it best to remove all of the masking around 1-2 hours after painting. This way the paint was still soft and resulted in the least amount of chipping etc at the edges, and allowed all the masking dots to come off the cleanest. If left for much longer, the dots tended to leave residue. 

A quirk of the anodised finish, is rather than hiding and filling all the imperfections / stamps, it highlights them! The "C" we added to the serial number looks like it belongs!

There is one masking dot i missed here - for the engine grounding point. I found that later and removed it.

Some people leave the internal area here bare - i decided to paint it. It won't be seen anyway once the starter is mounted.

The mis-positioned dot for the gorunding point is annoying - can't get everything right though.

The Money Shots

Some other little jobs

At the same time, i masked off and painted the rocket shaft covers - i actually did these twice. The first time i used the same dots as the case. These were too large and looked weird, so the second time i just bolted on some 1/4-20 rocket cover screws / washers. This looked a lot better. These were done in Silver-Blue. 

1st time around.

The masking not being concentric with the holes looked weird.

2nd time around.

I really like this blue silver color. I am considering doing the baffles in the same color.

Much better!

I also painted the dip stick, after sanding off all the old markings related to it's service on this engine in the Seneca! 

Finally, i deburred the inter-cylinder baffles. This engine did not come with these, so i purchased new ones. The 'ignition lead cover plate' was ludicriously expensive, so i just made one. These were painted in half aluminium (silver) and half black, to match the cylinders. 

Nice parts - but no deburring! These were only $124 each.

How is it that the baffles, with all their bends and riveting etc are $124, yet the little small flat plate is almost $80! Makes no sense.

These will be held on with some nice black 10-32 socket head screws, and standard MS21043 all metal locknuts (as it is on an engine). 

The 2 tone is a little overkill i know, but you only live once!

Basically printing money making this myself. 

So, that's it for the parts preparation stage. All i need to do is bake these for an hour at 100c - this needs to be done at the engine shop, as my oven is not big enough. Then, we start assembly!