Hi all.

 

I'm working on a project ea81 engine out of an old GL. One of the heads is warped a bit; probably 3 thousanths of an inch or so. In the past, I had luck doing a "ghetto" resurface job on an aluminum Toyota 22R cylinder head by attaching 300 grit emery cloth to a sheet of perfectly flat glass with spray trim adhesive. When that was dry, I soaked the emery cloth with WD40 and worked the head on the emery cloth in a figure 8 pattern for about 10 minutes. The head came out perfectly flat with a nice random finish on it. Never had a problem with that engine ever again after I did this.

 

Anyone ever try this with a Subie head? I know that a machine shop would laugh at this procedure, but it does work. I think I'll give it a try on this head and post some pics of the procedure.

 

Driveway engineering at its best.

If it works, thats all that matters.

In the past, and even today at some "lower end" machine shops, they used a big belt sander with emery cloth.

 

The same procedure you have done is a common practice in small engine and motorcycle shops, nothing wrong with it if it works, right?

 

But where did you get a piece of emery cloth that big? Ant pics of your set up?

and did you hold the glass? or did you have the glass on a table and ran the head over it? and also how thick was the glass cause of the glass can warp just a small amount and make it not perfectly flat

 

but hey good idea but I will still go into work and flycut mine when it is time if they are warped that is (have 2 engines needing resealing right at the moment one for a project and the other to swap into the 83 if I still have it when the time comes around or if it has the original engine when I get around to it and have it ready to install)

and did you hold the glass? or did you have the glass on a table and ran the head over it?

 

I used the thick metal deck of a table saw to lay the glass on. While my brother held the glass in place, I ran the head over the glass/emery cloth in a figure 8 motion. The last time I tried this, I used a thick piece of glass like they use for storefront windows (probably 1/2 inch thick).

 

It's been awhile since I did the Toyota head, but I remember that I had to glue several large strips of emery cloth together. As long as you resurface in a figure 8 pattern, it's not a big deal. Subie heads are kind of small, so less area is required. I'll try to get some pics posted.

 

Auto repair on a working man's budget.

Auto repair on a working man's budget.

 

Like using a 3 ton come along, 2 2x4s and the rafters in the garage as a cherry picker... or using the same setup to help install a transmission when working by ones self... I LIKE!

hey that is a neat idea, this is somethig i would definately do myself.

 

how do you determine how much you have taken off?

Same method only upside down....use a nice piece of granite held down to a table and the same spray adhesive or double sided tape to hold the emery cloth down.

Cheap granite pieces can be has at your local stone/tile shop....check the dumpster.I've gotten mine off of jobsites when the rich and famous toss out thousands of dollars worth of granite countertops.

A machine shop going out of business will also have perfect tables for you,used for checking tolerances and squareness,etc.They'll be a little more pricey,but perfect.

Ghetto,but effective enough for the backyard,mega-mile Subaru.

Stone(the right ones) won't crack as quick as glass.And it won't warp as glass does too.

I did the heads on my turbo that way.

 

Started with rougher emery then went to smoother. Checked for amount of warp left, and where the marks were from the emery cloth, to determine how much to take off.

 

Hush

That's f-in' brilliant!!!!!

 

At work I have used similar procedures to help smooth out the iron heads on our 1930's-1940's Desotos and Packards, but the thought of actually flattening out aluminum heads that way never occurred to me.

We used that system years ago, on two stroke motorcycle/snowmoble heads and jugs, works great. But we used 20" dia. sanding mesh off a floor sander and taped it to a hunk of glass.

I have also used a similar system on aluminum heads and blocks. Never had one blow afterward, so it must work ok;)

For those interested, the type of glass you want to use is plate-glass (as in "plate-glass window"). It is thicker, flatter and smoother than regular float-glass that you would use in residential windows.

 

I also have seen it done before, and if I recall a friend used that method to clean up my EA81 head once upon a time.

 

This method can be used for other flattening tasks, and if you need a smoother surface you can get various grinding and lapping compounds.

I've used a belt sander with really fine sand paper on it. Run it cross wises agains the head so you know you are keeping the sanding paper level..

 

It worked.. cars been running good for 6 months

To get a true granite flat plate like those used in machine shops, just go get yourself one from Grizzly. They are "B" grade plates, which have bilateral accuracy to .0001 ( one ten-thousandth), and are the most temperature stable medium available for this kind of work.

 

Model # G9649 is a 9" x 12", 2" thick plate and goes for $17.95. The shipping will kill you because of the sheer wieght, but it's well worth it if you do any kind of flat surface lapping operation. For the price you can't beat it and the dimensional accuracy will be considerably better than plate glass, although the measured difference of a lapped surface may be negligible, by its very nature lapping self corrects for surface tolerance variatons. These are also great for measuring twist/warp and flatnass, as an aide to your normal steel straight edge and feeler guage method.

 

www.grizzly.com <- you can spend hours there, I would recommend getting thier catalog if you don't get it already.

Enco has them also and free shipping;) . http://www.use-enco.com/CGI/INLMK3?PMK0NO=407251

Go with the 12" x 18" and one of these http://www.aaabrasives.com/shoponline.asp?point=moreinfo&catid=155&id=2699&pRange=0&iCurrentPage=2 and tape the edges. That would give you lots of room to do the figure-8 action.

Craven, will the Enco Grade B slab be good enough or is it wise to get the Grade A?

First project for me will be on a Rabbit diesel head.

Thanks.

Ray Mac.

For those that attempt this

Scoobaroo mentions a good point.

The emery cloth will plug with aluminum dust.

He used WD 40, I have used Gumout

to wash and lubricate the paper during the process.

 

A corollary to this method is to employ

a flat Arkansas stone or sharpening stone to surfaces

that can not be readily removed or are of an awkward shape

 

intake manifolds and water pumps come to mind.

These aluminum surfaces clean quickly if the stone is kept clean.

 

Excellent post - we need a USTB sub forum.

(Ultimate Subaru Tool Box)

The grade B is all you need for what we're doing here.

For those that attempt this

Scoobaroo mentions a good point.

The emery cloth will plug with aluminum dust.

He used WD 40, I have used Gumout

to wash and lubricate the paper during the process.

 

A corollary to this method is to employ

a flat Arkansas stone or sharpening stone to surfaces

that can not be readily removed or are of an awkward shape

 

intake manifolds and water pumps come to mind.

These aluminum surfaces clean quickly if the stone is kept clean.

 

Excellent post - we need a USTB sub forum.

(Ultimate Subaru Tool Box)

Not if you use a sanding screen or mesh as I stated. It has gaps Like a household door screen, that will hold quite a bit aluminum particals before you need to clean it. Then you just vacuum with a shop vac or what ever.

as you say

I have never seen this mesh

most of us use plain old emory cloth

This would work to cover your milling/sanding granite table also. The self adhesive backing would help on keeping it farely flat and uniform over the surface of the stone. http://www.onlineindustrialsupply.com/sandpaperrolls.html

as you say

I have never seen this mesh

most of us use plain old emory cloth

Skip

A sample of it you can find in any hardware store, they use it for sanding drywall. But it is too small 4 3/16 x 11 1/4 for what we need. That's why in the shop I worked in, used the 20" floor sanding disk and taped it around the edge. I don't like the idea of spray glue, I have never been able to spray that stuff down smooth (probably me), but why have a stone that is flat to 1/10,000 of inch and then spray on something that would very by whole lot more than that.

Craven

good point,

 

I will have a look for this sanding mesh

 

thanks for the tip

... I don't like the idea of spray glue, I have never been able to spray that stuff down smooth (probably me), but why have a stone that is flat to 1/10,000 of inch and then spray on something that would very by whole lot more than that.

Craven

How many angels DO fit on the head of a pin?

 

Translation: I imagine that the surface variation of ANYTHING that you attach to the surfacing surface will have a greater variation than the surface's flatness spec. The particles on the emery cloth, not to mention the backing itself, almost certainly has a greater variation.

 

As someone said, the lapping process should tend to even things out anyways...

this is interesting.