Are all cyl heads aluminum?

CubbyRI · #1 01-01-2021, 07:02 PM

Now its onto replacing the leaking head gasket and going to flatten the cyl head on wet/dry 320, on plate of glass first.

But I was wondering, are all these heads aluminum or are some cast iron?

Cubcadet_107 · #2 01-01-2021, 08:01 PM

There might be custom billet steel heads that people make specifically for pullers, but I do believe all heads are aluminum. Heck almost all air-cooled engine heads are aluminum. At least in the small engine world.

I do have this late 1930s Briggs and Stratton model "A" engine with a cast iron head, but that's the only small engine I've seen with a cast-iron head.

That's really strange with the link not working

Edit: may have figured out why the link won't work and why the website title is censored. Stumbled across this thread by chance: https://www.onlycubcadets.net/forum/...ad.php?t=47315
Posts 6,7,8 and 11 to be exact.

CubbyRI · #3 01-02-2021, 12:28 AM

So I watched the video on "milling" the head to flatness on wet sandpaper on a sheet of flat glass. Looks pretty easy. Which means I'll probably screw it up!
Now also know that all these heads are aluminum. I wonder why they leak and get warped so often and if anyone is making new heads?

Cubcadet_107 · #4 01-02-2021, 12:40 AM

They tend to warp and leak due mainly to the engine running too hot, whether it be clogged cooling fins or lean mixture. They also will warp or even melt if the head gasket blows, requiring them to either be welded back up and then sanded down or entirely replaced.

Essentially keep your cooling fins clean, mixture slightly rich (make sure the throttle shaft doesn't have too much end play either), and keeping your head bolts tight to spec should prevent any warping and leaking from excessive heat.

CubbyRI · #5 01-02-2021, 12:44 AM

cool thanks man!

R Bedell · #6 01-02-2021, 07:46 AM

Quote:

They tend to warp and leak due mainly to the engine running too hot, whether it be clogged cooling fins or lean mixture.

YUP, along with lack of inspection, proper maintenance, and if replaced, improper torquing,

Ambush · #7 01-02-2021, 11:59 AM

Some advice on "flat plating" your head or any surface. Smooth and flat are not the same thing. Glass is smooth, but not necessarily flat, think of a drinking glass. In the shop we used inhouse precision ground, thick steel plates. At home, before I used glass, I'd use thick particle board. That super heavy stuff often used for cheap furniture. It's hard, flat, smooth, cheap and holds the sandpaper well. 1" or two 3/4"s sandwiched. Clamp the paper to the board.

When you first start (220 grit wet and dry) put a couple fingers right in the middle and with very little pressure, do a couple of figure eights. That should show you any extreme gouges or warpage.

Ideally you should place a weight on the head then use your thumb and two fingers on the sides to push the head in circles and figure eights, alternating rotation. It may not make sense, but it will give you a much flatter surface. Placing your palm on the head and pushing it back and forth will give you a convex surface. Resist the temptation to push harder and go faster. Doing a good job can be slow and frustrating. And sure, guys will do that and say it worked fine, but so will just bolting your head back on with a new gasket....for a while. Sanding on a flat plate will always have tendency to cut more on the outside periphery and you have to mitigate for that as much as possible.

Spray your paper with brake cleaner often and blow it off then spray again before more sanding. That clears the paper and it well cut much faster. One sheet will usually be enough unless your tear it. The grit will get less as go for a bit smoother surface at the end. And you don't want a buttery smooth finish. A certain amount of "roughness" holds the gasket better, that's one reason why milling is the best choice. I am a professional at resurfacing, but I'm also an extreme DIY 'er and many things can be done well at the home shop with some basics tools, skills and patience.

Cubcadet_107 · #8 01-02-2021, 12:05 PM

I think it's about time for me to flatten my 107's cylinder head

CubbyRI · #9 01-02-2021, 12:13 PM

ambush thank you. I also have dykem spray (home machine shop) that will show the highs and lows. thank you for the advice about how not to distort the head with too much pressure.

All that said, I dont know for sure but I would guess that this is a 80/20 situation where almost no matter how new I am, it will be 80% of the way there and way better than what it is probably. Wonder what the practical deviation tolerance is before the gasket wont make it up to last as long?

Hadnt thought to use hd particle board. Wish I had a flat machinists stone table!

Red Dave · #10 01-02-2021, 12:30 PM

Quote:

Originally Posted by CubbyRI

Hadnt thought to use hd particle board. Wish I had a flat machinists stone table!

I never heard of using particle board, but if it is flat enough, why not?

I used a flat machinists stone in the past for heads on single cylinder engines, and to re-surface the bottom plates on Farmall oil pumps too. But that plate is back at the place I retired from, so I no longer have easy access to one.

We re-did the kitchen last summer and installed granite counter tops. They look just like a machinists stone.
I wonder if she would mind?