Cotton Waiex 191 - N191YX

[Bryan Cotton]

See picture:

It looks like the #3 exhaust valve has deformed. Seat is not flat - more concave. Also there were burrs at the top of every valve. Had to file the keeper groove edges to remove a burr so I could get them out.

Edit: I accidentally marked 3E as 1E.

[Bryan Cotton]

Ok, done screwing around. New heads on order.

We are taking the opportunity to replace the rear main corrosion prevention system. Also plan to split the case and see if we can find the reason why we can't get cruise oil pressure below 60+ psi.

Piston, rings, and cylinders look good.

[Hambone]

Following!

[pappas]

Make sure that you get a 3-angle valve grind. After I replaced the heads and did the 3-angle, my turbo ran like it had never before. The valve grind made a huge difference. Much more compression.

Sadly, it was a broken #4 exhaust valve adjuster foot that did in my most recent Waiex. But after the new heads and valve job, that thing was running AWESOME until the adjuster failed and put me in the desert, totaling the plane. If not for that, I would still be flying the Waiex and would be very happy with the performance and cost of ownership. Love the newly completed RV7-A, but it is much more expensive to play with!

[Bryan Cotton]

Make sure that you get a 3-angle valve grind.

Lou,
Did you use a local shop or send your heads out?

[Area 51%]

Fact is.... most VW heads already come with the 3 angle valve job. Some offer 4 or 5. In the performance world, the closer you can get to a radius at the seat, the better the air will flow. But, as a previous poster pointed out, the seat to valve margin suffers.
This picture is from a 1977 repair manual.

[pappas]

I have a friend with a custom Harley shop but he also built VW's for decades. He did it in his machine shop. I think any machine shop can do these. Yes, there are 4 and 5-angle jobs too. The price shouldn't be more than a couple of hundred, I don't think. The difference for me with the new heads and precision 3-angle was so much better than stock.

[Bryan Cotton]

[Bryan Cotton]

My #3 intake seat fell out.

[Bryan Cotton]

Motor is back on. Per Sonex, my new heads are headed for the machine shop this week.