Brand new cylinder head problems

[WesRagle]

Hi Scott,

I wasn't trying to single you out or anything like that. It just struck me as another example of a premature valve problem. But, your reply flags one of the basic questions.
Is one head manufacturer (Empi) better than another (MOFOCO)?

Best of Luck,

Wes

[Titanium Cranium]

I was told by Sonex that the Empi heads are supposed to be higher quality than the ones they used to sell from Mofoco, but if brand new Empi heads still require valve work to make them usable, then I'd say they're of no better quality. If there are so many known issues with these brand new heads, and we, as the buyers, are expected to re-build or repair these brand new parts, it really ought to be mentioned in the Aerovee manual. The manual only notes that we need to be sure any debris from the machining process is removed, and to bolt them on (obviously per the instructions). Disclosure seems to be where things are lacking with this. If we need to fix it ourselves, then so be it, but at least let us know ahead of time.

My heads were just dropped off at the shop yesterday to have the experts go through them and make them usable, so I'll post about the findings once I hear back from the shop.

[vigilant104]

A not-exactly related comment: Wouldn't it be great if we could buy a Type 1 VW head designed for use in airplanes? At our RPMs, we do not need the giant valves used by the 5000RPM+ street racers, and if we had smaller valves we'd have more "meat" in the heads and less cracking (just look at that tiny sliver of aluminum between the valve seats in our heads--they crack there a lot). But, at the same time, we could use some larger fins,esp near the exhaust ports--with air passages that are well designed for good flow and which aren't blocked by flash from the molding process. Go ahead and drill the second plug hole from the start--and both spark plug holes should come with steel Timesert-style inserts from the start (why not? About $20 in parts, not much trouble at all to install when the head is being made, and it makes it >much< less likely that a spark plug hole will get stripped out later). And, while we're at it, find a nice spot near the hottest part of each cylinder and tap a convenient hole there for the CHT sensor--maybe then, if we have a standardized location, we'll finally all be talking about the same thing when we discuss our CHTs.

I don't know if the costs would be crazy since market for these would be a lot smaller than the market for automobile use. But Solidworks and similar tools/CNC have made it a lot less expensive to make both molds and parts. And I wouldn't be surprised if folks building sand rails, etc for use in hot environments and at moderate RPMs wouldn't like a set, too.

The VW Type 1 makes a very good aero engine, but the heads are the known weak spot. With just a little more attention . . .

Now, back to our regularly-scheduled discussion.

Mark
(with a cylinder head still waiting for replacement. It's been a long time, and I admit to being a bit disheartened by the whole endeavor)

[WesRagle]

A not-exactly related comment: Wouldn't it be great if we could buy a Type 1 VW head designed for use in airplanes?

I wonder how different the Revmaster heads are.?.?

Ref. http://revmasteraviation.com/?p=125

I have heard of guys running Great Plains engines with Revmaster heads.

Wes

[vigilant104]

A not-exactly related comment: Wouldn't it be great if we could buy a Type 1 VW head designed for use in airplanes?

I wonder how different the Revmaster heads are.?.?

Ref. http://revmasteraviation.com/?p=125

I have heard of guys running Great Plains engines with Revmaster heads.

Wes

Thanks.
It looks like the Revmaster heads use the same "too-large" valves (35.5mm and 40mm) as the Aerovee, so there's no difference in that regard. Revmaster makes parts for automotive VW engines, I wonder if they make a less "aggressive" head with smaller valves but a lot of fin area.
Fins: I don't know for sure that the fin situation (size, count) is any different, but Revmaster makes some very nice parts and Joe Horvath is a stickler for quality. The air passages probably aren't filled with debris/flash, etc.
Plugs: I'm not crazy about the way the lower pugs are accessed in the Revmaster head (you have to remove a separate plate to get at them, so another gasket/spot for an oil leak).

[Titanium Cranium]

Just an update, I had a local shop that specializes in VW engines go through the new Empi cylinder heads. The valves and seats required a very heavy amount of lapping in order to get them to seal. They had to lap them so much that the valve stems extended more than before, enough that I had to adjust the pushrod lengths to avoid using too many shims under the rocker. Luckily, the work the shop did was perfect and the motor fired right up after assembly. All cylinders passed the leak-down test with the valves now holding exactly as they should. I can FINALLY get my plane back in the air.