Milling a head

So there is some damage on cylinder. Should I mill the mating surface true? It is on the surface between the head and cylinder.

Edit: Thread title should be milling the cylinder.

Is this a DD or a performance engine? And why is it apart? If all is generally OK, I'd think you'd get by fine with right type of "crushable" head gasket. (I don't know the trade name of the gasket.)

The head gasket may cover that up, but like Triumph5 said, what's it gotta do? High performance, high compression, mill it.

I've gotten away with a stiff board, like a 3" channel wrapped in emery to kiss and resurface the area.

Dan

It is on my CT3 project.

slap a DA sand disk on a plate of glass and sand away with wd40 as a lube. you just need to take off the high spots. the compresion ratio is only about 6:1 and the coper gasket will seal. You'd better check the "Squish" when you install the head.

44Dwarf wrote: slap a DA sand disk on a plate of glass and sand away with wd40 as a lube.

I am a bit lost here. Attach the sand disk to the glass.

I've done them on both of my Hodaka projects with a sheet of glass and some wet/dry sandpaper. Start with 220 but go slow! check a LOT! Once the big pits are gone, switch to 800 grit to remove the rest of the pits, then finish with 1000 grit. You probably won't remove enough to mess with the 'squish' (the edge of the combustion chamber area) but if it's sharp around the edges a little emery cloth work will fix that. Then check the piston deck height, if it's .020 or more below the top of the cylinder you are in good shape.

FWIW, on a ringding the only real 'sealing' area is the edge of the steel liner, that needs to be in nice shape. The rest isn't important.

Can some post a picture of sheet of glass sandpaper setup that they are talking about? I am lost.

In reply to 93EXCivic:

just like wrapping wet/ dry paper over a sanding block or paint stick, it's just using glass cause it's flat. I've used a 4" wide piece of 1/2" thick cold roll steel the same way on smaller engines. CRS is pretty darn flat compared to HRS and structural steel pcs. Also could try a thick n wide piece of milled steel or alum.

In reply to fasted58:

Ok sweet.

More reasons I like glass for being flat:

I tape a pane on top of my parts washer's flat lid then tape a sheet of wet/ dry over that, it's good for surfacing flanged gasketed parts (esp. alloy that may pit) like old t-stat housings. Keep the paper wet and do figure-8s w/ the part until the surface is uniform. If the surface under the glass isn't flat enuf for the glass add cardboard underneath.

Laying up flat fiberglass cloth/ resin sheets for patches or projects. I use old storm door glass, apply and wax off bout 3 coats of paste wax, spread resin on surface and apply pre-cut glass cloth, use roller to level cloth and remove air bubbles, let tack and repeat to how many layers ya want, let dry, remove w/ wooden wedge like door/ window tapered shim

Yup just as posted glass is flat so you have less chance of causing a wave / warp when sanding the surface. DA disks have glue on them that makes even easyer cause your not trying to hold the sandpaper and move the part.

44

For the truly fastidious read the article on scraping in the May/June copy of "HOME SHOP MACHINIST".

I use the paper on flat surface to sharpen knives and tools.

most modern kitchen counter-tops work without the pane of glass. Just place/tape the sandpaper on the counter.

44Dwarf wrote: Yup just as posted glass is flat so you have less chance of causing a wave / warp when sanding the surface. DA disks have glue on them that makes even easyer cause your not trying to hold the sandpaper and move the part. 44

If you don't have any of that handy, carpet or double sided tape have worked quite well for me.

It may not be 100% ok, but I've also used the cast iron top on our table saw for that too on small things that need done quickly (and that can be sanded dry).

Now that using your noggin! Yes table saw is nice and flat! you could even use (lightly) wd40 as lube

44Dwarf wrote: Now that using your noggin! Yes table saw is nice and flat! you could even use (lightly) wd40 as lube

Good call on the WD-40. A little degreaser would make for easy cleanup (if things get sloppy).