TOPIC:

I have been researching the best valve lapping compound since seeing videos of coarse and fine compounds, then only finding the Permatex tube at the auto stores. The Permatex lapping cpound is made from silicon carbide, which is the same crap that is in Scotch Brite pads that everyone says not to use for cleaning gasket surfaces.

Upon further research (google addict), I found that silicon carbide embeds in the metal and continues to destroy the surface. After lapping one calve, I could not seem to clean the surface enough to stop the grinding noise. I found a racing company that recommended not lapping their freshly machined valves and seats, and if you do, to only use 600 or finer grit. This sent me on a journey of discovery. Aluminum oxides seem better, but supposedly still embed. I found garnet lapping compounds as the only one that doesn't embed and washes away.

See these links and let me know what you think:

bbs.homeshopmachinist.net/threads/48387-...ded-lapping-compound

www.lapmaster.com/consumables/convention...mpounds/default.html

www.ws2coating.com/111n.aspx

I've never heard of real world issues with the lapping compound embedding. You sure this is a valid concern or is it just theoretical?

White lithium or moly-graphite assembly lube and some 13 micron or finer glass beads!
I have been doing this over 35 years.
Of course you have to clean it very good.
Had the stuff in my garage, I used it for free.

Nessism wrote: I've never heard of real world issues with the lapping compound embedding. You sure this is a valid concern or is it just theoretical?

It is the same theory of not using Brillo or Scotch Brite pads to clean gasket mating surfaces.

I ran across another thread where someone used Timeless to clean up the mating surfaces by putting one bolt thru the holes of say valve head and cover and leaving it loose, putting Timeless in between, rubbing the halves together, then repeating for each bolt hole in a star pattern. He said it created a vacuum tight seal with no gasket before he reassembled with gaskets. Would be cheaper than re-machining.

Read the links. I am really interested in this as a carbide free way of lapping. My valve has a crunchy sound still, even after a good cleaning. The valve is said to release the embedded silicon carbide in to the oil during break in and transfer the grinding material to bearings and journals.

Faulted Geologist wrote:
"My valve has a crunchy sound still, even after a good cleaning. The valve is said to release the embedded silicon carbide in to the oil during break in and transfer the grinding material to bearings and journals."

That doesn't sound too good........

Thank you so much for writing about this subject, I sure learned a lot

z1kzonly wrote: White lithium or moly-graphite assembly lube and some 13 micron or finer glass beads!
I have been doing this over 35 years.
Of course you have to clean it very good.
Had the stuff in my garage, I used it for free.

Corroboration of theory and function! Seeing your post, I searched for glass vs garnet hardness and found this:

Mohs hardness scale
Glass - 5.5
Garnet - 6.5 to 7.5
Steel- 8
Silicon Carbide - 9 to 10

www.reade.com/Particle_Briefings/mohs_ha...s_abrasive_grit.html

Read below the chart for further embedding talk. Other info states that the molecular shape of the garnet crystal is great for lapping work. If glass will lap valves, so should garnet. Since I have neither, i will be ordering some Green Label Timesaver.

I appreciate your input, z1kz, Zephyrrider recommended I contact you for your expertise in head work. Zeph has helped me extensively in PM land.

Here are some in different grits. Ed

www.brownells.com/gunsmith-tools-supplie...ounds-prod25658.aspx

Yea, I found that one while searching for aluminum oxide lapping compounds, then read in various places that AlOx is also embedding, although it is less bad than SiCarb. I clicked on the garnet one and started searching for info on those, finding out about the non embedding nature of the garnet lapping compound. This one is made for some function in gun care or manufacture.

I ended up buying the Timesaver from this website:
www.ws2coating.com/timesaverlappingcompounds.aspx

Got the 111 green label fine grit:
www.ws2coating.com/111n.aspx

It has to be mixed with oil, so this 3oz jar should go a really long way. I could probably also use it for polishing external steel, as one of their advertised uses is in honing cylinders to a really fine finish.

The yellow compound would probably work great as an aluminum polishing compound for external or exhaust ports.

They sell a kit of all 8 grits (4of each yellow and green) for $60. Kinda wish I would have seen that first.

Ed, have you used anything like this?

I haven't used any lapping compound; I've never had my bike's engine apart. I do know that when lapping rifle components, such as bolt lugs, it is important that the lapping compound doesn't embed and continue to lap after the desired level of contact between bolt lugs and receiver is achieved. So there are gunsmithing garnet lapping compounds that won't embed. Ed

There's a couple of key details that were overlooked.
The only valve compound Permatex has listed on their website, and what I believe you were looking at, is valve "grinding" compound, not "lapping". One of the suggested uses is sharpening lawn mower blades. Sound like pretty aggressive cutting to me. To me, Grinding is removing metal, while lapping is polishing metal. You were right to avoid it. You typically won't find lapping compound sold separate, You'll have to buy a valve lapping kit, which included the tool along with med and fine compounds for about $10.00. The little 1 oz. cans will be lifetime supply for most of us.
The embedded discussion link you provided was lapping iron/iron. Iron is a soft porous metal. The issue may still exist, but it would be of much less of a concern with steel/hardened alloy used for valves and seats.
You also mentioned seeing a higher end race shop recommending not to lap their valves. This was not due to embedding. Most likely these were Titanium valves/Beryllium seats. Titanium valves should not be lapped. They are hard coated to add durability. Lapping removes this coating. Ask any owner of a modern 4-stroke MX bike. I would typically see no valve adjustment for the first 30 hours. However, once an adjustment was needed, the valves would zero out to the smallest shim in less than 10 hours. Once the coating is gone, Ti valves wear very quickly. After the 3 sets of Ti valves, I changed my 450 to Stainless Steel They hadn't moved in 100 hours when I sold the bike.

MDZ1rider wrote: The only valve compound Permatex has listed on their website, and what I believe you were looking at, is valve "grinding" compound, not "lapping". One of the suggested uses is sharpening lawn mower blades. Sound like pretty aggressive cutting to me. To me, Grinding is removing metal, while lapping is polishing metal. You were right to avoid it. You typically won't find lapping compound sold separate, You'll have to buy a valve lapping kit, which included the tool along with med and fine compounds for about $10.00. The little 1 oz. cans will be lifetime supply for most of us.
The embedded discussion link you provided was lapping iron/iron. Iron is a soft porous metal. The issue may still exist, but it would be of much less of a concern with steel/hardened alloy used for valves and seats.

Yea, shows how much the people at the auto parts store know these days! The only thing sold at any of the 5 main big box auto stores (oreilly, auto zone, aaparts, etc) is that Permatex shit. What a joke! Sold right next to lapping sticks! Since the garnet is on the way, I will use that and post up some results. Based on your glass bead experience, things should go great. The link above sells 16oz for 2x the price of 3oz. Still wishing I had gotten the 8x sample set. Thanks for the input.

The only lapping kits available contain Clover or EzBore compound, both of which are the silicon carbide compounds. I think after hours of searching and reading that these are really bad to use. The only difference between these and Permatex is grit, but both are going to cut in to the metal too much and remain in the engine despite the best cleaning efforts. The valve will continue to settle in, requiring a re shim job way too soon. Will be using garnet to clean up the valves, then when I rebore and redo the engine as a whole in 10 years, I will buy new valves and have new seats put in and machined. Whatever the case may be, do NOT buy that auto store tube of Permatex! The cost of the garnet is essentially the same as SiCarbide, and if you are that tight on money you should look at the overall repair cost of gaskets and time invested.

Brownells sells a garnet compound for guns that is probaly already in paste form, and may use the Timesaver raw material in their formulation...

www.brownells.com/items/lapping-compound.aspx