Surfacing Cylinder Heads With Sandpaper and Granite Surface Block...

I was not even that young. Tried doing that on aluminum SBC heads, after screwing around on a flat gl*** plate for an hour, and not getting an even finish...took them to the local machine shop.

 

Adhesive back Porter Cable 80 in a roll is mighty handy. It sticks well to granite or gl***, and you can stick strips of it down very carefully with the edges flat and tight.

 

> <I tend not to over think this stuff these days> >

Yes. We can see that. Guess you ***ume gl*** won't bend mounted in its frame even if the rest of the table doesn't..

 

I have done it on granite and sand paper on a set of Subaru heads .
Those were aluminum and only 2 cylinders long and it was a PITA .
I have done motorcycle single cylinder heads this way also .
Its hard staying completely flat and the leading edge not have more material than the rest.

Id get them clean snd stripped my self and take them in have them magnafluxed and then milled.
If there warped get them checked .

 

Machine shop is definitely the best solution.
When using the sandpaper method
I used a sharpie to color the surface to see where the material was being removed.
Dan

 

No.

 

A lot of machine shops have a head surfacer that is just a big belt sander. I always wondered how flat the platen was after it had done a hundred or more heads.

Gary

 

No what?
Dan

 

No. Not a good idea.
Sanding is not machining.

 

You’re right it’s not machining but it does work and like @blue 49 says a lot of shops use a large belt sander. I and many others have lapped industrial compressor valves with either 400 grit sand paper on a flat surface or valve lapping compound on a gl*** plate. Either method produces a superior seal to a valve that was surface ground. It took a little experience and patience but a very good surface can be produced. Like I stated above I have used the sand paper/flat surface to produce very flat sealing surfaces on exhaust manifolds and a header that I built. The header had a 0.010 warp IIRC from welding and I got it to within a .001. Took some time but not an unreasonable amount maybe a hour total. I’ve never done a head but I see no reason a person can’t remove 0.004 and keep the head flat.
Dan

 

We do it to flatten transmission valve bodies. No reason it won’t work.

 

So...I guess this means you're an over thinker?
Sorry, it's no... I don't think it, the gl***, is going to "bend". Gl*** isn't ductile, it's actually hard and brittle. If that's a concern, get thicker gl***. It's a flat enough surface. Besides, if that's a concern use a straightedge and check like you did for head warping. And the point was do it yourself or spend money having someone else do it for you. I'm reading a lot of support for you can do it yourself and save. I'm in good company. But if you don't have the arms for it, then you pay. If it's badly warped and you don't have all day, you pay. That's it.

 

You guys that are saying, "Just take it to a machine shop" must have something available that I don't. A machine shop! Last thing I took to a machine shop was an hour away, and it took over a year to get back. A functional machine shop doesn't exist around here, that I know of.

 

Same here, two to three weeks minimum to see them again, or sand them, clean , and have back on the engine in a couple hours.
The shop I used had a fairly big cast iron table with a big grinding wheel in the center, he used to move the heads back and forth across the grinding wheel till the finish was even across both heads. It was dirty and dusty, but the heads never leaked.

 

I think this is what he was calling a wide belt sander, what I would too being a woodworker. But not one that needs this level of equipment.

 

Diesel heads have hardened pre chamber cups. You can't machine the heads with the cups installed. If you remove them, each would have to be ground to match. Typically they are surfaced on a belt sander made for this. The bed is long and wide enough to take a big ole' 6 cylinder truck head.

This is the first picture of one I found on the Google. I have seen bigger. Mike

 

One hour of my engine builder's labor cost less than one hour of my labor.

One-day turnaround.

 

Wow that’s quick, shops here you’re looking at one to four months depending on what’s being done. For me the shops I use are 1/2 or 1-1/2 hour one way drives.
The OP doesn’t want to wait on a shop and wants to do it himself to gain the skill and knowledge for the future.
If you’re in business that’s a whole different animal than a hobby.
Dan

 

If you have three you can get them truly flat.

 

Let us know how it turns out
Dan

 

I don’t have the inclination to want to try this in my shop. The last set of heads (SBC) I had surfaced ran me $95.00. This was 5 or so years back.
My buddy just had his FE heads surfaced for $135.00, but he lives in a much higher rent district than I do.
If I had to drive an hour, etc, I’d call ahead and try to schedule a time and wait.
Another thing to keep in mind is you don’t have to take them to an automotive machine shop. I only mention this as some feel that’s what they have to do.
The price is the same for a shop that still has manual machines vs CNC equipment.
I took a “machine shop 101” cl*** at the JC way back when, they had a Surfacer. I asked the instructor if it could do heads, etc, he told me as long as it could fit on the machine, no problem.
It was a machine I’d never seen in an automotive machine shop.

 

We used to flatten machine parts on a granite surface plate with Clover aka lapping compound. That being said blueing the surface would also be recommended. I would also get some measurements before with a dial indicator for a standard and see how much it’s removing.

 

There was a shop that I used in Columbus, GA, that had that setup. You could get it done the right way or get it done on the belt sander deal for about half of what the correct way cost. I always wondered who was going the cheap route; it certainly seemed like it wouldn't result in a completely flat surface.

 

I built a 7.3 IDI diesel a few years ago with pre-cups. My machinist was able to surface them, but he complained about how hard the pre-cups were and he had to make a few extra p***es because of it.

 

Yep. I have machine shops local to me, but it's still the time and h***le, and there's no guarantee that they won't lose your stuff, and no guarantee that they won't screw it up.

Thanks

 

I will. Was hoping to get to it this weekend, but was working on the roll cage and other engine stuff.

On a related note, I checked the deck on the block; and it's pretty damn flat. Couldn't get a .0015" feeler under the machinist straight edge anywhere. If I can get the heads within .0015" as well, I should be in good shape.

 

I resurfaced an intake manifold using sandpaper and a flat surface with wonderful results. The intake was out a mile and perfect when i completed the "machining" operation. That being said, it was a single-carb intake from an ancient 6hp Johnson outboard but still ...

 

Early Javelin?

 

Yes, an absolutely roached - but relatively solid - '72.

 

I would not use 80 grit paper. I would not attempt using a belt sander as it will quickly ruin a head. However, using a belt from a belt sander should work well if you get the correct grit and its wide enough. I think I would just use a few sheets of sanding paper glued in place and actually leave a small gap between them, maybe an 1/8 inch. I'd spray the glue around the edges of the paper and stick it to the surface and set some weight on it to let it cure overnight. Main thing is that the edges stay glued down . I'd look more toward something in the 250 grit area or maybe a little finer. If you cut scratches into the surface too deeply you will have a bigger issue. The grooves will give the grit a place to go and you can flush it out with the soapy squirt bottle. Just put 4 sheets or as much as you can on your flat surface, squirt soapy water on it and move the head about in an x shaped motion till it looks satisfactory to you.


I don't think you will be able to remove any taper from one end of the head to the other. It will remove a similar amount everywhere . If you were talking about variations in the surface itself......depressions so to speak, it should remove some of the high spots. Taking .004 off of a pair of head surfaces by hand is a difficult task. I would see how it goes. I think the main thing is to get a surface with just a little roughness rather than a glossy smooth surface. Head gaskets are designed to fill slightly uneven surfaces.