Valve Lapping Compound

[peterg]

I’m preparing for a top end rebuild this winter and am looking for valve lapping compound. I’ve read a number of threads on the matter and it seems that using a course grit followed by a fine grit is the way to go. The problem is I can’t find both. Powerbuilt has a package with both but I can’t find it available anywhere. I found Loctite Clover fine grit but not course. Permatex has 2 multi grit products, one that is mixed with water (doesn’t make sense to me to have water near the inside of a motor) and one that is premixed with grease. Any advice?

 

[RustiePyles]

https://www.amazon.com/Prime-Line-7...keywords=Valve+compound&qid=1633972722&sr=8-6

Not sure if you can order this Canada...

 

[peterg]

Now why didn’t that show up in my searches?! Thanks Rustie. It’s sold on Amazon.ca.

 

[5twins]

This eBay seller has both fine and coarse, and will ship to Canada .....

https://www.ebay.com/itm/111096472175?hash=item19dddda26f:g:WgoAAOxyu0BRfgZD

Have you tried all your local auto parts stores? Or maybe a specialty hot rod or speed shop? I bought my dual compound tin many years ago from a local auto parts store. I didn't even realize when I bought it that it contained both coarse and fine compounds, lol. But, I'm glad it did. The first time I used it, I was afraid to try the coarse so I used only the fine. It took forever, lol, and I never was able to get all the pits out of one of the valve seats. I mentioned this to my dealer and he said you have to use the coarse first, then finish with the fine. That's how I do it now and it works so much better and easier (quicker) than fine alone.

Searching for this CTA brand I have shows they have changed the container to plastic but unfortunately it appears to be N.L.A.

 

[arcticXS]

In my opinion, any major issues with seats and valves requires the use of valve seat cutters and a valve grinding machine. Excessive lapping will neither produce a good seal nor correct valve seat geometry.

 

[hovel]

Excessive lapping will neither produce a good seal nor correct valve seat geometry.

Agreed. "Excessive" is the key word. In doing a refresh on an otherwise sound engine, lapping will suffice, you can do it just about once. For a complete top end job, get out the cutters and grinder.

 

[peterg]

Thanks Guys. Once I have the valves in hand I’ll post picture to get input on their condition.

5twins. That’s the stuff I was looking for. $6 for product and $17 for shipping! Still cheaper than the same thing on Amazon.ca.

 

[5twins]

If you buy fine and coarse, will he combine shipping to save you a few bucks? Even though you only get 2 ounces, that's pretty much a lifetime supply because you don't use much, just a few dabs around the valve .....

I've had mine probably 20 years, done probably a dozen valve jobs, and have barely put a dent in it.

 

[arcticXS]

If you buy fine and coarse, will he combine shipping to save you a few bucks? Even though you only get 2 ounces, that's pretty much a lifetime supply because you don't use much, just a few dabs around the valve .....

I've had mine probably 20 years, done probably a dozen valve jobs, and have barely put a dent in it.

5T,
When looking at your picture, the lapped "band" seems a bit wide to me. I wonder what the width spec is for the valve seats.

 

[hovel]

I wonder what the width spec is for the valve seats.

Wonder no more. The factory manual says the band width should be .083" and the seat width .051" for both intake and exhaust. The band width is what we're seeing in 5twins picture, the seat width is centered in the band width. Page 1-6 in the '75 manual.

 

[arcticXS]

Wonder no more. The factory manual says the band width should be .083" and the seat width .051" for both intake and exhaust. The band width is what we're seeing in 5twins picture, the seat width is centered in the band width. Page 1-6 in the '75 manual.

Thanks! 51 thou is about 1.3 mm, so not very wide. It does not take too much effort with coarse compound to end up way too wide....

 

[5twins]

There is a wear limit for the seat and that is 2mm. It's easy enough to check with a 6" steel rule graduated in MM on one side. I do check them and I've never had a seat grow wider than the 2mm wear limit after lapping.

 

[5twins]

Here's the specs from the factory shop manual .....