Leaky exhaust valves

[rizzz]

rizz,
From what I see the valves and head look good. The one area of concern is the dark area on the lower 1/3 of the #3 cylinder as compared to the #4.
This usually indicates a leak at the cylinder/head mating area. Maybe it's just the camera angle.
Most old beetle style engines did not have a head gasket (copper ring) and leaks like this were common.
As you know, always install a new copper gasket after head removal.
Frank
ONEX 090

Thanks Frank,

I’ll have a look at that cylinder/piston again next time I’m at the airport.
I was not running any copper gaskets and my VW guy did tell me that after taking the heads off either I should use them, or,
pay an extra $90 and get the mating surface of the heads machined completely square and flat again, which is what I’m doing.
Do you believe we should always use the copper head gaskets? I have read different opinions on this topic.

Cheers,
Michael

[NWade]

Do you believe we should always use the copper head gaskets? I have read different opinions on this topic.

FWIW, Sonex/AeroConversions is very clear in their manuals and always requires a copper gasket to be installed.

Why wouldn't you use the gasket?

--Noel

[rizzz]

Do you believe we should always use the copper head gaskets? I have read different opinions on this topic.

FWIW, Sonex/AeroConversions is very clear in their manuals and always requires a copper gasket to be installed.

Why wouldn't you use the gasket?

--Noel

Hi Noel,
Mine is not an AeroVee. More like a Hummel (but not exactly).
I don't believe Hummel use gaskets, not sure about GP or RevMaster.
Original VW bugs did not have them either as someone else mentions.
VW "experts" seem to have different opinions on copper gaskets, some say they do more damage than good, others say they are the best thing ever.
Just read this thread on one of the VW forums, the so called experts violently disagree on this topic:
https://www.thesamba.com/vw/forum/viewt ... e7ede18100

[Klimek]

Michael,
I do believe the copper rings are the way to go. Prior to 1972, VW, on the 12, 13, 15 and 1600cc engines there were no head gaskets used. (copper rings) with the
introduction of the type II and type IV came the 1700cc engine which had a head gasket ring which was designed to crush and seal. This engine also had a new style
head studs, 10 or 12mm threads on each end (can't remember which) but the shaft of the stud was 8mm, same diameter our AeroVee engines use. The stud is designed to stretch and be more forgiving
than the old 10mm stud used. I believe, in my experience, the 8mm stud is better at keeping the head tight against the cylinder with the use of a gasket, copper ring, therefore
almost eliminating head to cylinder leaks. The lower studs are also longer and can tend to stretch with heat more than the shorter upper studs, therefore proper and regular
maintenance is important. Generally the lower stud nuts are found to be of a lower torque value, "loser", than the uppers, sometimes found laying the valve cover.
With all that said, yes, copper rings are the way to go. The addition of copper rings to your engine now will affect the compression ratio and so will require a recalculation
and probably machining and checking the cc's of the head to get it back where you want it to be.
I could have just said "YES!" but that's no fun.
Now going out to work on my ONEX.
Be safe,
Frank

ONEX 090

[NWade]

VW "experts" seem to have different opinions on copper gaskets, some say they do more damage than good, others say they are the best thing ever.
Just read this thread on one of the VW forums, the so called experts violently disagree on this topic:
https://www.thesamba.com/vw/forum/viewt ... e7ede18100

Hrm. Its true that some people debate their usefulness on that Samba forum thread (and others). But I don't see anyone presenting evidence that a copper gasket causes damage or problems. Yes, one or two people simply claim that the copper gasket is bad; but they don't provide details or evidence as to why it is bad. They also don't provide any credentials - they're simply voices on the internet, and for all we know they could be completely ignorant of the subject matter. Saying that "experts" are disagreeing is a potential misnomer. Its easy to assume that people who make strong-sounding posts online are experts; but its a dangerous mental trap!

For instance: I've assembled other 4 to 8 cylinder engines for various auto-racing teams, but I'll admit that my VW-based engine has yet to run.

Given my experience, though, I can't see how the copper gaskets would do harm - as long as you install and torque everything properly. I might be overlooking something, so if you've spotted a specific argument against them that provides an explanation of how they're bad then I'd love to see it. But random strangers on the internet complaining about cost or how they've seen gasketed engines fail? Those kinds of unsupported claims shouldn't carry any weight.

--Noel

P.S. For anyone online that claims that the original VWs didn't come with copper gaskets, remind them that some of their cars also didn't originally come with seatbelts! Good ideas can come along later and make things better. :D

[Fastcapy]

I have done quite a bit of research into the copper gaskets.

My finders are this:

They are not used to seal the cylinder to head area. Some VWs had a sealing gasket to prevent exhaust gases in "stale air" systems, but it is not the same as the one we put in the head between the head and cylinder.

Many people simply use them for and many feel their actual purpose is to adjust deck height without using barrel shims. You can get steel in head shims to do the same but copper is better for heat differences.

Many like them for 2 main reasons. First, they will melt/be destroyed before the head. The resulting compression loss can actually prevent additional damage to the head, better to blow out a $30 gasket than a $300+ head. Second, they prevent needing to resurface the head where it mates to the barrel as the copper takes the abuse and not the aluminum head.

Some don't like them but it seems to be more of a thing that they are not needed and are just something to waste money on. They also say but the original didn't have them so why change it now. People say they have had heads fail using them, but people have had heads fail not using them as well.

So to most people in the car world it just seems to be a preference. I run them in my motor and will keep doing so because everything I have read about them, and it was a lot, the benefits outweigh the possible negatives. Even though they are not really a "head gasket" nor do they actually function like one (head gaskets are really only needed for liquid cooled motors to keep coolant and oil out of the cylinders and compression in the cylinders) they do seem to have other benefits for what little they cost.

[rizzz]

I think I'll install the head gaskets this time around, but I'm going to check with Scott at Hummel and my VW guy.
(although chances are I could get a different response from each and still have to make up my own mind).

This is what my numbers were:
Bore: 94mm
Stroke: 86mm
Combustion chamber volume: 66cc
Deck height 0.103"
Spacer used 0.020"
--> Compression ratio: 7.8:1

Adding a 0.040 copper head gasket would reduce my compression ratio to 7.3:1, still pretty good setup for use with both automotive fuel and AvGas (I'm seriously thinking of starting to use automotive whenever I can)

However, my heads are being flycut as part of the service so will need to remeasure the combustion chamber volume as it will likely reduce somewhat as well and possibly increase compression ratio again.

[WaiexN143NM]

Hi rizz,
Before you switch to auto fuel, think about using 100LL and tcp. Auto fuel doesnt last long, maybe a month? And watch out for ethanol in fuel. Will toast your fuel probe if it has any ethanol. Some lead is good, maybe not as much as 100LL has. Most airports i visit dont have auto fuel. If you have any leaks you can identify from the blue dye. If its sits for a couple months its still good. Just my opinion. There may be some sonex drivers out there who use auto fuel exclusively and have good luck. I worry about vapor lock on a hot day and warm inside the cowl.

WaiexN143NM
Michael

[Corby202]

My GP VW did not use copper head gaskets, I never had any problems.

First, they will melt/be destroyed before the head

Isn't the melting point of copper higher then aluminum??.

[Klimek]

Michael and Noel,
I hope my input was not taken wrong. I do not claim to be an expert.
My statement that most VW's did not come with copper rings is a statement of fact and not thrown out there because I claim to be an expert.
I hope I just misunderstood the reply to my post. I DO support the use of copper rings. They compress to seal, take up very irregularities in the mating surfaces
between head /cylinders, help heat transfer, expand and contract to maintain seal and can be and are used, In some cases, to set the compression ratio.
Michael, it sounds to me like you are headed down the right path. I set my engine compression ratio to 7.5:1 which will allow for either fuel available at most
airports.
Noel, I am not an expert, just experienced in the building of a lot of VW engines. Most for street use, some for racing. I am a very modest person, love my family and friends and hate tooting my own horn. I have 24 years of training by VWMA, starting in 1970, and employed
as a "unit room tech". I was also elected to the Volkswagen Service Guild in 1974, one of 12 tech inducted that year. I consider myself lucky to have been involved
with VW during the heyday of the air cooled revolution. If I misunderstood, I apologize.

On another note, are there any of the VW type II / IV engines being used in aviation regularly? They have always seemed to be well suited for modification for aircraft
use. In stock form they provide more torque which would reduce the need to "go big or go home". The one drawback seems to be the drive hub on the crankshaft.
The weight might also play in with the lack of aftermarket parts. Just something to think about.
Frank
ONEX 090