# VW head quality issues **URL:** \ **Category:** Aerovee\ **Created:** [January 18, 2026, 1:05am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352 "2026-01-18T01:05:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [January 18, 2026, 1:05am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/1 "2026-01-18T01:05:14Z")
Last fall I picked up a spare AeroVee. A few weeks ago I was having problems with valves and I pulled a head off the spare motor. This motor had Empi heads from Sonex and they had about 20 hours on them. As I started looking at the seats and valves, they were really not great. I was considering a head swap but held off. We know the purpose of the hobby is to buy tools. So I ended buying a Neway valve seat cutting set. I’ll talk more about that over in the tools section. But in playing with the new toy, I made a discovery. The Neway tools use a tapered pilot that jams into the valve guide. Cutting is done concentric to the guide. What I found is that both exhaust seats in this head were not very concentric with the guide. It cut on one side at first and I had to cut a lot to clean up the opposite side. I have a new set of CB Perf heads that I’m going to put bottom plug holes into. I have to get the Bridgeport to my hangar and tool up first. But I’m also going to do a 3 angle valve job on the brand new heads and see how good the machining is. I am thinking that a valve job on new heads will improve the sealing and longevity of the valves. Stay tuned. ---
**Author:** ![q2rd2100](https://sonexpilots.org/user_avatar/sonexpilots.org/q2rd2100/32/1761_2.png) [@q2rd2100](https://sonexpilots.org/u/q2rd2100)\ **Post date:** [January 23, 2026, 8:13pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/2 "2026-01-23T20:13:42Z")
Wow, Bryan, you must be my improved better brother. I also picked up a spare Aerovee last fall. It’s a 2.1 with Empi heads. My current engine is a 2.0. Note of interest, I’ve had both heads on my current engine rebuilt with new valve seats. The first one I had rebuilt with new Empi valve seats. This is now on cylinders #3/4. Since installed I’ve been loosing my exhaust valve clearance at around 10 hours flight time on #3. Still have fair compression on that cylinder when pulled through cold and hot, although I’ve not done a leak down. The second head I had rebuilt I had CB exhaust seats installed, it is now on cylinder #1/2. I’ve had almost no valve clearance loss on those exhaust valves. I wonder if the CB seats are harder material than the Empi seats. I think you’ll be happy with your O44’s. ---
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [January 23, 2026, 8:23pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/3 "2026-01-23T20:23:31Z")
> [@q2rd2100](#): > > improved better Those adjectives are a stretch! But I am looking forward to swapping heads. ---
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [February 3, 2026, 2:26pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/4 "2026-02-03T14:26:43Z")
> [@q2rd2100](#): > > I wonder if the CB seats are harder material than the Empi seats. Rene’, I think that is a possibility. It’s also possible the machining is better on the CB heads. It was discouraging how much material I had to remove to get the seats to cut all the way around. I really think they are not centered well on this particular head. ![cut seats all 4](https://sonexpilots.org/uploads/default/original/2X/a/ae6bd96c617cb213a4e6ca682735e8b723e7c19d.jpeg) ![cut seats closeup](https://sonexpilots.org/uploads/default/original/2X/4/4ee2e4e757c5c03e9d33d5c5707350117a00d5ef.jpeg) I’ve got all 4 seats cut in this head and they look really good. I’ll have to check the valve geometry as I think they may need another shim under the rocker blocks. I’ll be curious if this head has better valve lash stability when I’m done, just because of better concentricity. ---
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [February 14, 2026, 5:23pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/5 "2026-02-14T17:23:09Z")
I’ve posted this in the old forum but worth another broadcast I believe. The heads I’m working on now probably have the best casting quality I’ve seen, but still not good enough. Check out the casting flash in what is probably the most critical cooling fin location: ![Screenshot_20260214-111037](https://sonexpilots.org/uploads/default/original/2X/1/1b0eff04cf1a9d1387c8b1ca1b25d803ebc11dfa.jpeg) I made a thin sanding disk using a piece of 7075, double sided tape, bushings, and 60 grit paper. ![Screenshot_20260214-111023](https://sonexpilots.org/uploads/default/original/2X/0/0b5b145e81b7361ba3c2ba2b1a4ef9938c2d0a8a.jpeg) I flip the disk over to sand the other surfaces. The head is bolted to the table. ![Screenshot_20260214-111055](https://sonexpilots.org/uploads/default/original/2X/b/b3327fd71fee3240986d2d6296019e175c97ef50.jpeg) Here is the picture after sanding. ![Screenshot_20260214-111112](https://sonexpilots.org/uploads/default/original/2X/c/ccd579bb217b5628d11144e48060d3ec880e1d9a.jpeg) I believe this is a mandatory step! ---
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [February 14, 2026, 5:45pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/6 "2026-02-14T17:45:46Z")
I should mention my first pass is with a cutoff wheel. Otherwise the sanding disk hangs up on the casting flash. ![Screenshot_20260214-114357](https://sonexpilots.org/uploads/default/original/2X/8/8451297b0fe5c37fecfb5a7e6a42b339f051950f.jpeg) ---
**Author:** ![Pfhoeycfi](https://sonexpilots.org/letter_avatar_proxy/v4/letter/p/eada6e/32.png) [@Pfhoeycfi](https://sonexpilots.org/u/Pfhoeycfi)\ **Post date:** [May 27, 2026, 7:08pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/7 "2026-05-27T19:08:53Z")
For those that have had their vw heads rebuilt, was it locally or did you send them out? I cant seem.to find options close by. My need is not immediate …just looking to the future. ---
**Author:** ![q2rd2100](https://sonexpilots.org/user_avatar/sonexpilots.org/q2rd2100/32/1761_2.png) [@q2rd2100](https://sonexpilots.org/u/q2rd2100)\ **Post date:** [May 28, 2026, 7:56pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/8 "2026-05-28T19:56:31Z")
I have had mine done at a local engine shop. Just make sure you tell them it’s for a dune buggy or performance car. Some machine shops will refuse to do them if they know it’s for an airplane, especially an experimental one 😳. Ask me how I know. Most small engine shops have a guru VW guy, you have to ask around, you’ll be surprised. ---
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [May 28, 2026, 8:55pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/9 "2026-05-28T20:55:33Z")
I’ve got a buddy from Ohio, not on the forum, who uses a local machine shop. All of the coolest AeroVee guys have a second set of heads ready to swap on. That lets you rebuild the first set at your leisure. ---
**Author:** ![Pfhoeycfi](https://sonexpilots.org/letter_avatar_proxy/v4/letter/p/eada6e/32.png) [@Pfhoeycfi](https://sonexpilots.org/u/Pfhoeycfi)\ **Post date:** [June 1, 2026, 1:37pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/10 "2026-06-01T13:37:24Z")
Thanks… ---
**Author:** ![JKS](https://sonexpilots.org/letter_avatar_proxy/v4/letter/j/bb73d2/32.png) [@JKS](https://sonexpilots.org/u/JKS)\ **Post date:** [June 1, 2026, 9:44pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/11 "2026-06-01T21:44:31Z")
" …the coolest AeroVee guys have a second set of heads ready to swap on. That lets you rebuild the first set at your leisure. " Back in the day, a bud said essentially the same thing about the XKE. Gotta have 2 to always have 1 that’s drivable. Followed by “I love 'em, they breakdown just when you feel like working on them.” Well done. ---
**Author:** ![q2rd2100](https://sonexpilots.org/user_avatar/sonexpilots.org/q2rd2100/32/1761_2.png) [@q2rd2100](https://sonexpilots.org/u/q2rd2100)\ **Post date:** [June 6, 2026, 3:54pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/12 "2026-06-06T15:54:02Z")
The super cool guys even have a complete spare Aerovee engine 😎 I’m in the midst of my annual. I lost an unbelievable .055" total exhaust valve creep on cylinder #3 over the last 100 hours since rebuilding that head. Leak down is still acceptable at 70/80. I was going to pull that head this spring for rework, but will wait until fall now since we’re going out of country for 2 months. Rule of thumb is to pull the head if you loose more than .035". No other issues. ---
**Author:** ![WesRagle](https://sonexpilots.org/user_avatar/sonexpilots.org/wesragle/32/1450_2.png) [@WesRagle](https://sonexpilots.org/u/WesRagle)\ **Post date:** [June 28, 2026, 12:10pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/13 "2026-06-28T12:10:07Z")
Ok, who is going to be the first to try the new RevMaster heads? [Ref. RevMaster 063 Cylinder Heads.](https://revmasterautomotive.com/shop/ols/products/063-cylinder-heads) Wes ---
**Author:** ![q2rd2100](https://sonexpilots.org/user_avatar/sonexpilots.org/q2rd2100/32/1761_2.png) [@q2rd2100](https://sonexpilots.org/u/q2rd2100)\ **Post date:** [June 29, 2026, 12:13am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/14 "2026-06-29T00:13:34Z")
They sound great and I’d buy set if I didn’t already have a spare set of Empi’s from Sonex on my shelf. Wonder if the still have the tooling and would be willing to drill the bottom spark plug holes. Thanks for posting Wes. ---
**Author:** ![WesRagle](https://sonexpilots.org/user_avatar/sonexpilots.org/wesragle/32/1450_2.png) [@WesRagle](https://sonexpilots.org/u/WesRagle)\ **Post date:** [June 29, 2026, 1:36am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/15 "2026-06-29T01:36:18Z")
> [@q2rd2100](#): > > Wonder if the still have the tooling and would be willing to drill the bottom spark plug holes. I don’t know exactly what is going on with RevMaster, but rumor has it that they intend to spin the aviation branch back up once some sourcing issues are resolved. So, I assume they would have retained the means to add the second plug. I don’t know much about their engines, but I seem to remember that the second plug was in an odd location. Couldn’t the second plug hole be added by anyone who drills the bottom holes for other brands of heads? Lots I don’t know about heads. Wes ---
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [June 29, 2026, 2:27am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/16 "2026-06-29T02:27:32Z")
> [@WesRagle](#): > > Couldn’t the second plug hole be added by anyone who drills the bottom holes for other brands of heads? I have another non-EMPI set of heads that need holes drilled. Because it’s a different casting, I’m going to carefully figure out where the holes need to go and make tooling for the Bridgeport. Those combustion chambers look different than any of the heads I have, so you would need to carefully figure out where to put the holes. ---
**Author:** ![q2rd2100](https://sonexpilots.org/user_avatar/sonexpilots.org/q2rd2100/32/1761_2.png) [@q2rd2100](https://sonexpilots.org/u/q2rd2100)\ **Post date:** [June 29, 2026, 4:04am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/17 "2026-06-29T04:04:14Z")
Hey Wes. The original Revmaster 2100 heads had the bottom plugs in a tough to service location. You had to remove the rocker arm assemblies then two special made caps to access the plugs. Pain in the derriere! The later 2300 heads had the plugs in the same location as Aerovee and Greatplains heads. Made sense. I know Mofoco has a jig and tooling to drill bottom plug holes, but doubt they’ll want to drill other manufacturers heads. Back in the day when we had 4 Revmasters running at our airport, a machinist buddy built a metal jig to mount the heads so anyone with a mill could machine them. Me and others would borrow the jig and have machine shop drill the bottom plug holes into our CB044 heads. Wish we still had that jig kicking around. I think someone else posted one on the internet built out of wood a long time ago. Basically it tilts the head at the right angle for the machining bit to stay vertical. Bryan Cotton looks to be very handy at machining and building jigs 😁 😉 ---
**Author:** ![WesRagle](https://sonexpilots.org/user_avatar/sonexpilots.org/wesragle/32/1450_2.png) [@WesRagle](https://sonexpilots.org/u/WesRagle)\ **Post date:** [August 10, 2026, 3:08am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/18 "2026-08-10T03:08:36Z")
Hi Guys, A guy gave a presentation at AirVenture on “How to Drill a VW Head for Dual Ignition”. He posted the notes from his presentation on another forum. I uploaded them here, see attachment. The presentation was not recorded, but for those considering this, there might be some information of interest. The gentleman also said he would answer questions, via email, for anyone truly interested (address in the notes). Wes [How to Drill a VW head for Dual Ignition.pdf](https://sonexpilots.org/uploads/short-url/jvzmIPIRuC9nYSTqk8CYKxWrRqA.pdf) (9.9 MB) ---
**Author:** ![Bryan\_Cotton](https://sonexpilots.org/user_avatar/sonexpilots.org/bryan_cotton/32/760_2.png) [@Bryan\_Cotton](https://sonexpilots.org/u/Bryan_Cotton)\ **Post date:** [August 10, 2026, 3:19am UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/19 "2026-08-10T03:19:49Z")
That’s awesome. I’ve bought some 1" aluminum stock, the 6061 type instead of pine to make my fixture. ---
**Author:** ![q2rd2100](https://sonexpilots.org/user_avatar/sonexpilots.org/q2rd2100/32/1761_2.png) [@q2rd2100](https://sonexpilots.org/u/q2rd2100)\ **Post date:** [October 19, 2026, 8:06pm UTC](https://sonexpilots.org/t/vw-head-quality-issues/5352/20 "2026-10-19T20:06:31Z")
To follow up on my Jan 23 post. I removed the 3/4 head this weekend, the one that had the constant valve clearance loss every 10 hours. 107 hours on this head since rebuild with Empi seats. There is a definite issue with the Empi seats. I lost 0.057" on the #3 exhaust valve over the 107 hours. Interestingly it still had good a good leak down number at 70/80. I’ve not experience this much clearance loss and valve seat recession on any previous VW head. Crazy! Head was always run within temp limits and typically saw 325 deg F in flight on #3 and below 375 deg F on climb out. Was also dismayed to see the mushrooming on the #3 intake valve stem. I will make removing the rockers and inspecting the valve stems an item on my annual inspections. ![IMG_1202](https://sonexpilots.org/uploads/default/original/2X/a/a4a5a03b0c68f92c7fbf15b935920e96d8cf221e.jpeg) ![IMG_1203](https://sonexpilots.org/uploads/default/original/2X/f/f82ca5e91740c9d3ecba2e530c20a7256bfc3efe.jpeg) ![IMG_1206](https://sonexpilots.org/uploads/default/original/2X/9/9f007f11c718b64016d113e17ade5031dfa7921c.jpeg) ![IMG_1215](https://sonexpilots.org/uploads/default/original/2X/4/435b4f3def05a761547b561b06a658b2a6e33bd3.jpeg) [Next page](https://sonexpilots.org/t/vw-head-quality-issues/5352.md?page=2)