1973 Rebuild

[Takhli]

The polished valve Matt posted is the test mule, but I have since completed one full set of intake valves.

I started at the drill press, spinning each valve to check for head run-out and wobble. If they checked out (and all of them did) I weighed and measured each one. Eventually, we had two sets of valves fairly consistent in length and weight. We also have a third set but the measurements are not so consistent.

The polishing work started on the combustion faces, spinning the valves at about 650 RPM while using a Dremel tool and grinding stone against the direction of rotation, to smooth away the casting marks. Working with a gentle, steady pressure it only took a few minutes to clear the marks from the valve.

I followed the grinding with 80-grit abrasive cloth until the grinding stone marks were no longer visible; then moved to successively finer wet-dry papers until I had the finish I wanted. A small bit of WD-40 on the paper helps, and it didn't take more than fifteen-minutes to polish each valve's combustion face.

When I was done with one set of six valves I moved to their transition at the valve stem base. Measuring often until the transition blended smoothly, I used a very fine file to carefully turn down the neck of the transition. After this I polished the head and stem transition the same way I did the combustion face, but stopped at the 600-grit finish. Next, I'll re-face each valve with the factory angles, and dress their tips.  

Admittedly, the mule is way over the top, and 600 grit paper will achieve a very nice finish. Next I plan to experiment to get a swirl pattern on the port-side of the valves, but the combustion chambers are polished so I want the combustion face of the valves polished, as well.

More photos to follow, but I'll let Matt do that.

Edited September 20, 2018 by Takhli

[Patcon]

Are you expecting any advantages from polishing the valves in this manner?

[Matthew Abate]

Polyester primed

[Matthew Abate]

Are you expecting any advantages from polishing the valves in this manner?

Not by themselves, but as part of the complete job of reworking the head.

[siteunseen]

Seems like @Diseazd guy at Datsun Spirit does a "swirl" polish on his?  Quick read says polishing the back side gives better results.  Sounds like I'll be copy catting Matt and Takhli.  Something to do one day. 

Edited September 21, 2018 by siteunseen

[Matthew Abate]

It’s also a good zen exercise for meditation purposes, considering cars are therapy. [emoji6]

[Takhli]

It's true...   It's a really great exercise for meditation.  

Matt was interested in some swirl-polished valves when we started, but we're also trying to keep expenses down. I know polishing needed to be done before I could get a swirl pattern, so that's where I started.

As far as advantages are concerned; it's something I did on the drone engines I built. With no other mods to ports,  testing proved those engines performed better with polished valves. 

But Matt is also correct in stating its part of a complete package: The bottom end mostly delivers strength and durability, while the top end develops the power.  For Matt's engine, the ports will have the valve pockets cleaned and matched, the port entries and exists will match the manifolds (like most folks do), the head will have the stock three-angle valve work but held to tight specifications, and the chambers will be CC'd and polished. The valves are just a part of all that.

 

Edited September 22, 2018 by Takhli
Additional information

[Takhli]

On 9/18/2018 at 3:28 PM, Patcon said:

How did you accomplish that?

As promised, here are a few photos; they are all the same valve, the test mule.

       

1. Chuck the valve into a drill, hand tight; spin the valve  and break out the Dremel tool

2. Remove only enough metal to clean away the markings 

3. 80-grit cloth is next; use it until the grinding marks and casting pits are removed

 

80-grit surface, below. Don't go crazy near the margin.

 

4. Follow with 150-grit, 220-grit, etc., until you have the finish you want. I stopped at 600 on the port-side of the head, but took it to 2000 on the face (over kill but it was fun, and only six or seven minutes of polishing).

150  surface below                                                                                                                                                                      

220   

320

400; probably just fine

600

1000

1500

2000

Edited September 23, 2018 by Takhli

[siteunseen]

That looks great. What speed did you use on the drill?

Thanks for the details, my next fun thing to do. Cliff

[Takhli]

19 hours ago, siteunseen said:

That looks great. What speed did you use on the drill?

Thanks for the details, my next fun thing to do. Cliff

Drill press speed was 650 RPM. The 80- and 150-grit were abrasive cloth; everything else was wet-dry with a little WD-40.

Have fun; that's what it's all about.

[Captain Obvious]

Did you put your right foot in?

[siteunseen]

7 hours ago, Captain Obvious said:

Did you put your right foot in?

And shake it all about.

You're a nut Hokey Pokey!

Edited September 24, 2018 by siteunseen