Revmaster rebuild


Mike Steinsland
 

Hi Guys,
Pretty soon I will be getting my Revmaster rebuilt. As far as I know the engine is stock as in the original kit.
I'm looking for advise on the minimal upgrades recommended and things to pay attention to during the rebuild.
I'll listen to anything you have to say.
I will be having this done by a local engine builder.

Cheers,
Mike


Edwin Medina
 

I email revmaster for an estimate to upgrade horse power to 80 and overhaul and the price they give me was $5,500!
The 2300 brand new cost about $9,800 it’s $4,300 more but is new. All depend how much you Plan to expend! I think $5,500 it’s not to bad price!
What HP have yours?
Edwin

On Fri, Apr 29, 2022 at 08:11 Mike Steinsland <MIKESKUSTOMS@...> wrote:
Hi Guys,
Pretty soon I will be getting my Revmaster rebuilt. As far as I know the engine is stock as in the original kit.
I'm looking for advise on the minimal upgrades recommended and things to pay attention to during the rebuild.
I'll listen to anything you have to say.
I will be having this done by a local engine builder.

Cheers,
Mike


Mike Steinsland
 

When I convert that to Cdn $ add shipping on to that I'll be close to 9K.
I'll have it done locally
I'm pretty sure the engine is the lower hp
It looks to have the original heads on it

On Fri., Apr. 29, 2022, 8:39 a.m. Edwin Medina, <captmedina@...> wrote:
I email revmaster for an estimate to upgrade horse power to 80 and overhaul and the price they give me was $5,500!
The 2300 brand new cost about $9,800 it’s $4,300 more but is new. All depend how much you Plan to expend! I think $5,500 it’s not to bad price!
What HP have yours?
Edwin
On Fri, Apr 29, 2022 at 08:11 Mike Steinsland <MIKESKUSTOMS@...> wrote:
Hi Guys,
Pretty soon I will be getting my Revmaster rebuilt. As far as I know the engine is stock as in the original kit.
I'm looking for advise on the minimal upgrades recommended and things to pay attention to during the rebuild.
I'll listen to anything you have to say.
I will be having this done by a local engine builder.

Cheers,
Mike


J-Dubs
 

I bought the higher hp heads from Scott Casler for about $1000 a couple of months ago.  It's money well spent in my opinion. 


Edwin Medina
 

That’s great price !
He have a web page?
Edwin

On Fri, Apr 29, 2022 at 09:04 J-Dubs <jwerth55303@...> wrote:
I bought the higher hp heads from Scott Casler for about $1000 a couple of months ago.  It's money well spent in my opinion. 


J-Dubs
 

https://www.hummelengines.com/


Edwin Medina
 

Thank you!
Edwin

On Fri, Apr 29, 2022 at 10:05 J-Dubs <jwerth55303@...> wrote:
https://www.hummelengines.com/


Michael Dunning
 
Edited

On Fri, Apr 29, 2022 at 07:11 AM, Mike Steinsland wrote:
Hi Guys,
Pretty soon I will be getting my Revmaster rebuilt. As far as I know the engine is stock as in the original kit.
I'm looking for advise on the minimal upgrades recommended and things to pay attention to during the rebuild.
I'll listen to anything you have to say.
I will be having this done by a local engine builder.

Cheers,
Mike

Mike, if I may:
1) How many air-cooled VWs has your local shop built?
2a) How familiar are you with aircraft engines? and...
2b) aircraft-converted VWs in particular?

I ask since most folks seem to either ship the engine to Revmaster or do the work themselves and tasking work out adds one extra wrinkle. There is an interesting mix of VW and Revmaster specialty tools involved depending on how deep into the engine you want to go.

I've spent the last three (enjoyable) years answering your question for myself and the last six (relaxing) months gathering parts and tearing mine down...so I will try to share what I know as best I can. Just search my name on here and look at my build log: https://eaabuilderslog.org/?blproject&proj=7rri10ikZ&cat=all

Good luck,
Michael
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


britmcman99
 

Following some sage advise from a very successful Q-2 driver I went with 94mm barrels and pistons, And because at the time I didn’t want to deal with the lower spark plug access I bought Great Plains cylinder heads (I think the latest version of Revmaster heads have a new design where you don’t need to remove the valve train to get the lower plugs out), buy the aluminum crank case. It is 7 pounds heavier than the magnesium case but will not be prone to cracking so would definitely recommend that. The addition of the 94mm barrels included a volumetric compression equalization and adjustment that inky case may have actually lowered the compression  a tad (referred to CC the cylinder heads). You would get around 2163cc displacement and even with the 94 mm pistons, the lower compression and aluminum crankcase you might expect the engine to be more robust. 

Phil


On Apr 29, 2022, at 10:08 AM, Michael Dunning <dunningme@...> wrote:



[Edited Message Follows]

On Fri, Apr 29, 2022 at 07:11 AM, Mike Steinsland wrote:
Hi Guys,
Pretty soon I will be getting my Revmaster rebuilt. As far as I know the engine is stock as in the original kit.
I'm looking for advise on the minimal upgrades recommended and things to pay attention to during the rebuild.
I'll listen to anything you have to say.
I will be having this done by a local engine builder.

Cheers,
Mike

Mike, if I may:
1) How many air-cooled VWs has your local shop built?
2a) How familiar are you with aircraft engines? and...
2b) aircraft-converted VWs in particular?

I ask since most folks seem to either ship the engine to Revmaster or do the work themselves and tasking work out adds one extra wrinkle. There is an interesting mix of VW and Revmaster specialty tools involved depending on how deep into the engine you want to go.

I've spent the last three (enjoyable) years answering your question for myself and the last six (relaxing) months gathering parts and tearing mine down...so I will try to share what I know as best I can. Just search my name on here and look at my build log: https://eaabuilderslog.org/?blproject&proj=7rri10ikZ&cat=all

Good luck,
Michael
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


britmcman99
 

To add another note, I sent my engine back to Revmaster for the rebuild I wrote about earlier. 

Phil


On Apr 29, 2022, at 10:08 AM, Michael Dunning <dunningme@...> wrote:



[Edited Message Follows]

On Fri, Apr 29, 2022 at 07:11 AM, Mike Steinsland wrote:
Hi Guys,
Pretty soon I will be getting my Revmaster rebuilt. As far as I know the engine is stock as in the original kit.
I'm looking for advise on the minimal upgrades recommended and things to pay attention to during the rebuild.
I'll listen to anything you have to say.
I will be having this done by a local engine builder.

Cheers,
Mike

Mike, if I may:
1) How many air-cooled VWs has your local shop built?
2a) How familiar are you with aircraft engines? and...
2b) aircraft-converted VWs in particular?

I ask since most folks seem to either ship the engine to Revmaster or do the work themselves and tasking work out adds one extra wrinkle. There is an interesting mix of VW and Revmaster specialty tools involved depending on how deep into the engine you want to go.

I've spent the last three (enjoyable) years answering your question for myself and the last six (relaxing) months gathering parts and tearing mine down...so I will try to share what I know as best I can. Just search my name on here and look at my build log: https://eaabuilderslog.org/?blproject&proj=7rri10ikZ&cat=all

Good luck,
Michael
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Mike Steinsland
 

Thanks for the input guys.
The guy I'm having do this is a tool and die maker and has built many VW engines in his years. He now mostly works on truck diesels.
I understand the advantage of the newer heads, but I'm not sure what the domino effect will be if going to a larger cylinder.
Will I end up having to change a bunch of other things as well?


Michael Dunning
 

Mike,

Per your questions, I decided to add some things from a draft blog post and Revmaster accident/incident history I've had kicking around for ages; read as little or as much as you like. YMMV. A lot of the sentences that follow will have embedded links to the "source material". For reference, my engine is S/N A-2605 delivered on July 9, 1985 with all options, minus a turbo.

1) First and foremost, a major cause of issues with the original QAC Revmaster was a compression ratio (CR) that was far too high. My original booklet show this clearly, with listed CRs of 9.3 to 9.4 (9.35 to be exact).


 
 

At "some point" Revmaster did "some thing" to reduce the CR as shown in the latter manuals but I have no idea what.



The latest Sonex AeroVee 2.1 Assembly and Installation Manual and Great Plains manuals recommend 7.0 for mogas and 8.0 for 100LL for increased longevity. Your engine builder can help you with this. Combinations of various cylinders, heads, and shims can get you there using a calculator like this: CB Performance Engine Calculator

2) The original "75 HP" Revmaster heads just...aren't. To make matters even worse, you need to carefully check that the cooling passages aren't blocked off by casting flash. Highly recommend Mark Langford's page on the subject.

3) The magnesium engine case is now known to age harden and develop cracks. Various fixes such as "deep studding cylinder 3" and "welding in behind cylinder 3" do help at our high continuous power settings but the real issue is the age hardening. The ultimate solution is a new aluminum case that does not suffer from this problem. Unfortunately, the special machining for the Revmaster propeller hub means you can't just buy a stock VW case. If you decide to reuse the case (like I did) then expect a 250-400 hour TBO until it inevitably cracks. As John Monnett says, that's realistically a couple years (at least) of flying though. Note that a high(er)-aluminum content (AS21) magnesium case is different than an all-aluminum case.

Here are some additional videos/articles, in no particular order:
1) Engine Assembly Tips for the Type 1 VW with Steve Bennett (EAA Webinar)
2) Q-talk 117 - The Little Engine that Could
3) Q-Talk 163 - Revmaster Cracked Case Repair
4) Engine Rebuild in 2013 (Calvin Thorne's blog)
5) Q-talk 153 - Kuhlman & Dirks Q2
6) History of Prop Hubs (Bob Hoover's blog)
7) Aero VW Cooling Limitations (Bob Hoover's blog)
8) The VW Aircraft Engine for DragonFly/Q-Bird with Steve Bennett (YouTube)
9) AeroVee Engine History: SuperVee to AeroVee (YouTube)

Personally, I am proceeding with 92mm "thick wall" cylinders (92mm base / 94mm top) to help with cylinder to head sealing and 68cc Panchito heads which purport to have better cooling as documented on my build log. This should yield a bolt together, no shim CR of 7.38 while reusing my original case. Ultimate proof will come when it flies.

Hope it helps,
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Mike Steinsland
 

Oh boy does this ever help.
You've given me lots to consider!

Thanks so much for putting this info
 together in one spot it's going to save a lot of digging.


On Wed., May 4, 2022, 11:37 p.m. Michael Dunning, <dunningme@...> wrote:
Mike,

Per your questions, I decided to add some things from a draft blog post and Revmaster accident/incident history I've had kicking around for ages; read as little or as much as you like. YMMV. A lot of the sentences that follow will have embedded links to the "source material". For reference, my engine is S/N A-2605 delivered on July 9, 1985 with all options, minus a turbo.

1) First and foremost, a major cause of issues with the original QAC Revmaster was a compression ratio (CR) that was far too high. My original booklet show this clearly, with listed CRs of 9.3 to 9.4 (9.35 to be exact).


 
 

At "some point" Revmaster did "some thing" to reduce the CR as shown in the latter manuals but I have no idea what.



The latest Sonex AeroVee 2.1 Assembly and Installation Manual and Great Plains manuals recommend 7.0 for mogas and 8.0 for 100LL for increased longevity. Your engine builder can help you with this. Combinations of various cylinders, heads, and shims can get you there using a calculator like this: CB Performance Engine Calculator

2) The original "75 HP" Revmaster heads just...aren't. To make matters even worse, you need to carefully check that the cooling passages aren't blocked off by casting flash. Highly recommend Mark Langford's page on the subject.

3) The magnesium engine case is now known to age harden and develop cracks. Various fixes such as "deep studding cylinder 3" and "welding in behind cylinder 3" do help at our high continuous power settings but the real issue is the age hardening. The ultimate solution is a new aluminum case that does not suffer from this problem. Unfortunately, the special machining for the Revmaster propeller hub means you can't just buy a stock VW case. If you decide to reuse the case (like I did) then expect a 250-400 hour TBO until it inevitably cracks. As John Monnett says, that's realistically a couple years (at least) of flying though. Note that a high(er)-aluminum content (AS21) magnesium case is different than an all-aluminum case.

Here are some additional videos/articles, in no particular order:
1) Engine Assembly Tips for the Type 1 VW with Steve Bennett (EAA Webinar)
2) Q-talk 117 - The Little Engine that Could
3) Q-Talk 163 - Revmaster Cracked Case Repair
4) Engine Rebuild in 2013 (Calvin Thorne's blog)
5) Q-talk 153 - Kuhlman & Dirks Q2
6) History of Prop Hubs (Bob Hoover's blog)
7) Aero VW Cooling Limitations (Bob Hoover's blog)
8) The VW Aircraft Engine for DragonFly/Q-Bird with Steve Bennett (YouTube)
9) AeroVee Engine History: SuperVee to AeroVee (YouTube)

Personally, I am proceeding with 92mm "thick wall" cylinders (92mm base / 94mm top) to help with cylinder to head sealing and 68cc Panchito heads which purport to have better cooling as documented on my build log. This should yield a bolt together, no shim CR of 7.38 while reusing my original case. Ultimate proof will come when it flies.

Hope it helps,
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Mike Steinsland
 

Hey Michael
Do the Panchito heads have dual plug option?



On Thu., May 5, 2022, 7:09 a.m. Mike Steinsland via groups.io, <MIKESKUSTOMS=GMAIL.COM@groups.io> wrote:
Oh boy does this ever help.
You've given me lots to consider!

Thanks so much for putting this info
 together in one spot it's going to save a lot of digging.


On Wed., May 4, 2022, 11:37 p.m. Michael Dunning, <dunningme@...> wrote:
Mike,

Per your questions, I decided to add some things from a draft blog post and Revmaster accident/incident history I've had kicking around for ages; read as little or as much as you like. YMMV. A lot of the sentences that follow will have embedded links to the "source material". For reference, my engine is S/N A-2605 delivered on July 9, 1985 with all options, minus a turbo.

1) First and foremost, a major cause of issues with the original QAC Revmaster was a compression ratio (CR) that was far too high. My original booklet show this clearly, with listed CRs of 9.3 to 9.4 (9.35 to be exact).


 
 

At "some point" Revmaster did "some thing" to reduce the CR as shown in the latter manuals but I have no idea what.



The latest Sonex AeroVee 2.1 Assembly and Installation Manual and Great Plains manuals recommend 7.0 for mogas and 8.0 for 100LL for increased longevity. Your engine builder can help you with this. Combinations of various cylinders, heads, and shims can get you there using a calculator like this: CB Performance Engine Calculator

2) The original "75 HP" Revmaster heads just...aren't. To make matters even worse, you need to carefully check that the cooling passages aren't blocked off by casting flash. Highly recommend Mark Langford's page on the subject.

3) The magnesium engine case is now known to age harden and develop cracks. Various fixes such as "deep studding cylinder 3" and "welding in behind cylinder 3" do help at our high continuous power settings but the real issue is the age hardening. The ultimate solution is a new aluminum case that does not suffer from this problem. Unfortunately, the special machining for the Revmaster propeller hub means you can't just buy a stock VW case. If you decide to reuse the case (like I did) then expect a 250-400 hour TBO until it inevitably cracks. As John Monnett says, that's realistically a couple years (at least) of flying though. Note that a high(er)-aluminum content (AS21) magnesium case is different than an all-aluminum case.

Here are some additional videos/articles, in no particular order:
1) Engine Assembly Tips for the Type 1 VW with Steve Bennett (EAA Webinar)
2) Q-talk 117 - The Little Engine that Could
3) Q-Talk 163 - Revmaster Cracked Case Repair
4) Engine Rebuild in 2013 (Calvin Thorne's blog)
5) Q-talk 153 - Kuhlman & Dirks Q2
6) History of Prop Hubs (Bob Hoover's blog)
7) Aero VW Cooling Limitations (Bob Hoover's blog)
8) The VW Aircraft Engine for DragonFly/Q-Bird with Steve Bennett (YouTube)
9) AeroVee Engine History: SuperVee to AeroVee (YouTube)

Personally, I am proceeding with 92mm "thick wall" cylinders (92mm base / 94mm top) to help with cylinder to head sealing and 68cc Panchito heads which purport to have better cooling as documented on my build log. This should yield a bolt together, no shim CR of 7.38 while reusing my original case. Ultimate proof will come when it flies.

Hope it helps,
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Michael Dunning
 

They do not. Great Plains or Scott Casler will be happy to do that machining for you, if you wish.

https://www.greatplainsas.com/0160-/-machine-work-only.aspx 

https://www.hummelengines.com/

If you just want to use the toolbox a.k.a. wallet, you can get "airboat" heads from MOFOCO and use cylinder barrel shims. These are the exact heads that Sonex uses...just don't tell anyone 🤫

https://www.mofoco.com/item/Mofoco_040A_40mmX35_5mm_Cylinder_Head_DUAL_12mm_spark_plug_holes_92mm_bore_/3520/c52


And of course, new $995 Revmaster heads are always an option. Ultimately, this is what Mark Langford ended up using at the end of that article I posted earlier.

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

Hope it helps,
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Troy Zawlacki
 

Michael are you saying to use the Mofoco heads (55cc chamber) plus a 3mm copper washer? That would add close to 20cc. But it looks like the Revmaster heads are just 58cc. Now im wondering what the volume is of my original Revmaster heads (old style spark plug access) since Joe told me to add the copper washers.

There is one irritating thing about these washers for others to be aware of. The washers space the heads off the cylinder jugs and therefore affect intake alignment, baffling, and most importantly exhaust tube fitment. I’m sort of married to the copper rings now that I’ve made all those three things fit perfect, but I believe Joe from Revmaster said the new heads wouldn’t require them… sigh.

TAZ

On May 5, 2022, at 7:14 PM, Michael Dunning <dunningme@...> wrote:

They do not. Great Plains or Scott Casler will be happy to do that machining for you, if you wish.

https://www.greatplainsas.com/0160-/-machine-work-only.aspx 

https://www.hummelengines.com/

If you just want to use the toolbox a.k.a. wallet, you can get "airboat" heads from MOFOCO and use cylinder barrel shims. These are the exact heads that Sonex uses...just don't tell anyone 🤫

https://www.mofoco.com/item/Mofoco_040A_40mmX35_5mm_Cylinder_Head_DUAL_12mm_spark_plug_holes_92mm_bore_/3520/c52
<Screenshot_20220505-205652.png>

And of course, new $995 Revmaster heads are always an option. Ultimately, this is what Mark Langford ended up using at the end of that article I posted earlier.

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

Hope it helps,
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Mike Steinsland
 

See now I'm learning stuff I did not know.
What's with the copper washers?

On Fri., May 6, 2022, 12:29 a.m. Troy Zawlacki, <troyzc3@...> wrote:
Michael are you saying to use the Mofoco heads (55cc chamber) plus a 3mm copper washer? That would add close to 20cc. But it looks like the Revmaster heads are just 58cc. Now im wondering what the volume is of my original Revmaster heads (old style spark plug access) since Joe told me to add the copper washers.

There is one irritating thing about these washers for others to be aware of. The washers space the heads off the cylinder jugs and therefore affect intake alignment, baffling, and most importantly exhaust tube fitment. I’m sort of married to the copper rings now that I’ve made all those three things fit perfect, but I believe Joe from Revmaster said the new heads wouldn’t require them… sigh.

TAZ

On May 5, 2022, at 7:14 PM, Michael Dunning <dunningme@...> wrote:

They do not. Great Plains or Scott Casler will be happy to do that machining for you, if you wish.

https://www.greatplainsas.com/0160-/-machine-work-only.aspx 

https://www.hummelengines.com/

If you just want to use the toolbox a.k.a. wallet, you can get "airboat" heads from MOFOCO and use cylinder barrel shims. These are the exact heads that Sonex uses...just don't tell anyone 🤫

https://www.mofoco.com/item/Mofoco_040A_40mmX35_5mm_Cylinder_Head_DUAL_12mm_spark_plug_holes_92mm_bore_/3520/c52
<Screenshot_20220505-205652.png>

And of course, new $995 Revmaster heads are always an option. Ultimately, this is what Mark Langford ended up using at the end of that article I posted earlier.

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

Hope it helps,
--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Michael Dunning
 

Mike,
These videos aren't a great explanation of the process but they'll do:

1) Compression Ratio & Deck Height
2) Cylinder Barrel Shim Installation
3) Copper Head Shim Installation

Check out pages 20-21 of the AeroVee manual for a better explanation.

Troy,

I'm saying you need to calculate whatever shim(s) you need using the process outlined in the AeroVee manual. Everything you say about fitment is true, which is why I'm hoping to avoid shims. Maybe even eliminate some oil leaks to boot. One thing I've heard on the VW boards is that the copper heads shims require that you check and re-torque the head fairly often as the copper tends to "squish" over time - have you experienced that at all? Not sure how applicable the experience of VW drag racers really is to us...

You'll notice that all the numbers in the 80's Revmaster brochure check out when using the stock VW 1mm / 0.040in deck height and 55cc heads. I plan to cc my "75 HP" as-delivered heads for practice while I'm waiting on my new heads and will post the results. Still need to laser cut the plastic discs though.



--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Mike Steinsland
 

Keep it comin' 
I love it
This is all SOOO helpful

Thanks guys
You're making it a lot easier for me to make decisions 
Sure do appreciate it!

On Fri., May 6, 2022, 9:38 p.m. Michael Dunning, <dunningme@...> wrote:
Mike,
These videos aren't a great explanation of the process but they'll do:

1) Compression Ratio & Deck Height
2) Cylinder Barrel Shim Installation
3) Copper Head Shim Installation

Check out pages 20-21 of the AeroVee manual for a better explanation.

Troy,

I'm saying you need to calculate whatever shim(s) you need using the process outlined in the AeroVee manual. Everything you say about fitment is true, which is why I'm hoping to avoid shims. Maybe even eliminate some oil leaks to boot. One thing I've heard on the VW boards is that the copper heads shims require that you check and re-torque the head fairly often as the copper tends to "squish" over time - have you experienced that at all? Not sure how applicable the experience of VW drag racers really is to us...

You'll notice that all the numbers in the 80's Revmaster brochure check out when using the stock VW 1mm / 0.040in deck height and 55cc heads. I plan to cc my "75 HP" as-delivered heads for practice while I'm waiting on my new heads and will post the results. Still need to laser cut the plastic discs though.



--
-MD
#2827 (still thinking about planning on visualizing how to finish building)


Sam Hoskins
 

I'm saying you need to calculate whatever shim(s) you need using the process outlined in the AeroVee manual. Everything you say about fitment is true, which is why I'm hoping to avoid shims. Maybe even eliminate some oil leaks to boot. One thing I've heard on the VW boards is that the copper heads shims require that you check and re-torque the head fairly often as the copper tends to "squish" over time - have you experienced that at all? Not sure how applicable the experience of VW drag racers really is to us...

I don't know nuthin' about the Revmasters, but I do want to relate what I know about one of our fatalities. Bob (his last name escapes me at the moment) had acquired a Q-2 with a Revmaster.  Prior to this, he had flown with me for better than an hour in my Q-200. 

I remember him saying something about tightening up his cylinders or heads. He was out flying one day and he had an engine failure. He put it into a plowed field and flipped over. There was a small fire, which did not consume the aircraft, but the coroner said he died of smoke inhalation. The FAA investigation said the cause of the engine failure was due to the cylinders (or heads?) not being torqued and loosed up.

Sorry I'm fuzzy on the details, but I'm sure it's discussed in the Q-List archives.

Be careful out there and proceed with knowledge.

Sam

On Sat, May 7, 2022 at 9:43 AM Mike Steinsland <MIKESKUSTOMS@...> wrote:
Keep it comin' 
I love it
This is all SOOO helpful

Thanks guys
You're making it a lot easier for me to make decisions 
Sure do appreciate it!

On Fri., May 6, 2022, 9:38 p.m. Michael Dunning, <dunningme@...> wrote:
Mike,
These videos aren't a great explanation of the process but they'll do:

1) Compression Ratio & Deck Height
2) Cylinder Barrel Shim Installation
3) Copper Head Shim Installation

Check out pages 20-21 of the AeroVee manual for a better explanation.

Troy,

I'm saying you need to calculate whatever shim(s) you need using the process outlined in the AeroVee manual. Everything you say about fitment is true, which is why I'm hoping to avoid shims. Maybe even eliminate some oil leaks to boot. One thing I've heard on the VW boards is that the copper heads shims require that you check and re-torque the head fairly often as the copper tends to "squish" over time - have you experienced that at all? Not sure how applicable the experience of VW drag racers really is to us...

You'll notice that all the numbers in the 80's Revmaster brochure check out when using the stock VW 1mm / 0.040in deck height and 55cc heads. I plan to cc my "75 HP" as-delivered heads for practice while I'm waiting on my new heads and will post the results. Still need to laser cut the plastic discs though.



--
-MD
#2827 (still thinking about planning on visualizing how to finish building)