2.1 MV rebuild

[jberger]

[90weekender]

Jberger

You are right. These guys will make custom size copper head gasket rings for $20/each.

http://www.headgasket.com/contact.html

I just need to send specs.

[jberger]

[90weekender]

So here's a thought experiment. If I am getting custom gaskets made, and 10.5:1 CR may cause pinging, should I order thicker piston head gaskets?

I found a calculator online here:
https://www.summitracing.com/newsandevents/calcsandtools/compression-calculator

Turns out CR is highly sensitive to gasket thickness. I found that a 1.7mm thick gasket gives me just under 10:1 CR. Below are compression calculations based on different thickness rings (stock 1.2mm - 1.7mm):

I'm not sure my "Effective Dome Volume" numbers are correct. Anyone see mistakes?

R

[jberger]

I don't mean this to sound disrespectful.. but it most likely will. Based on the questions you are asking, it seems that you are in over your head. Go back to the beginning and do the reading and research. Trial and Error (key word is error) is the DIY way.. or buy a high performance engine from an actual shop with the experience. A thicker head gasket will increase your deck height making the combo more prone to detonation. Plenty of info to glean via threads here and on the shoptalkforums but there will still be trial and ERROR. I'll parrot what I typed via PM... a bone stock engine build will be reliable and perform as well as one could hope. Verify what you have and if it was an original MV build (IE, not Cofap P&C set or other), then clean everything.. mic everything.. put it back together and thrash it with the pedal to the floor all day... every day. Once you deviate from stock, it may be better and it may not be.

I'll add that your "stock" build could include a 2252 cam for a nice performer. I say that because to my knowledge there are still no OG cams available. The 2252 is NOT a HOT cam. It's actually more mild than stock but it increases dynamic compression by a tad. I know because I have spent the time to degree this, stock and numerous other cams as well as have run time with different combo's. One of the vans I like to drive the most is an 89 westy with a NOS stock piston and liner set and a 2252, stock size tires and gearing.

YMMV
J

[MarkWard]

When you torque the heads, you need the head gasket and the cylinder seals to compress equally to properly seal. And yes the gasket thickness does have an affect on the compression ratio more than you might imagine.

I’m probably in the same camp as jberger. There are enough details to get right on a stock engine, let alone changing compression ratio and the valve train.

So you don’t take this the wrong way, my first engine was in my brothers 71 beetle. In those days it was JC Whitney. Lots of % power gain with all the “bigger” parts. I had no feel for building an engine. First indicator was we needed to pull start it. It ran like a scalded dog for the entire summer vacation. On his way to UNC the continuous load was too much and the engine failed. He sold it for bus fare.

Fast forward to today, I build 10000 rpm racing engines. I have experience and experience comes at a cost. I now know all the mistakes I made and the details I missed on my brothers bug. You can read everything and watch every video and you won’t have that “feel” for building engines that you get from experience. See above.

Not trying to discourage you. You might get lucky. The compression ratio calculators are fun to play with, but don’t assume. You’ll need a burret for cc’ing your combustion chambers and piston relief. Then do the math yourself to calculate your actual compression ratio. Best of luck.
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[Howesight]

For the benefit of others reading this thread, and for the original poster, I will just chime in on the issue of deck clearance and knock. If the OP makes errors and learns, great, but I reckon it's good to know why you are trying out various aproaches to the build.

So long as you do not permit too much carboning up of the combustion chamber and piston top, you can safely run 0.035" to 0.040" deck clearance. (Racing engines rebuilt monthy can run much tighter deck clearance, but you are not racing). With a Mann Pro-vent properly installed, carbon build-up is likely to be well-controlled.

Why 0.040" you ask? The space between the flat portions of the piston and the head is referred to as the "squish" zone or the "quench" zone. Squish and quench are separate concepts. Squish refers to increased charge motion caused by forced displacement of fuel-air mixture from the "squish/quench" zone. Charge motion is good. Charge motion helps speed up combustion which helps reduce the tendency to knock because combustion is completed (or nearly so) before knock can occur. The quench function is simply the cooling effect that the comparatively cold piston top and cylinder head surface have on the burning fuel/air mixture that is in close proximity to these cooler surfaces. At distances greater than 0.040, for instance, far less of this cooling effect is transmitted since air is a good heat insulator. Remember that it is end gases that are primarily responsible for knock. Tight deck clearance is intended to give greater charge motion and reduce the heat of the end gases. Without these knock-fighting aspects, probability of knock is increased.

This is why simply using a thicker head gasket to reduce compression in hopes of reducing the tendency to knock is counter-productive. Despite all this, installing a knock control system on any WBX with increased compression is the safest approach to controlling knock. But with a proper deck clearance, the knock conrol system will not have to retard spark advance as much and you will retain the power that the higher compression was intended to give you.
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'86 Syncro Westy SVX

[90weekender]

Gents,

I cannot do this project successfully without the help of this community and experts like you...that's why I chose to start this thread. The fact that you take time and offer advice (even if it may be hard for me to accept) proves that you care. How great is that?!! I hope you can stay engaged.

To JBergers comments:

[MarkWard]

I’m not saying you can’t build a high power engine. It’s that there are enough details to get correct building a stock engine. Without building experience you may miss a detail.

The air is pretty thin at 9000 feet. Your only going to improve those speeds slightly and you may actually introduce more stress on the transaxle. A chain is only as strong as the weakest link.
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[hdenter]

A DJ engine IS a stock engine. It just wasn't sold here. There are plenty of DJs running around europe. I would suggest that you make your changes in stages. I could not agree more with Mark about building an engine with little or no experience. These parts are not cheap nor is machine work. I'm not saying it can't be done, just weigh the costs of a mistake if a detail is missed. Hands with experience will feel if a rod bearing is just a bit too tight when let fall from 3 o'clock to 6. Maybe you could contact Rocky Jennings and see if he would do a 2.1 build with your pistons... In any event, maybe start with just the pistons and a stock cam with the OE rockers and exhaust. Then add the 10cent exhaust If you still want to add a few ponies, go for the ratio rockers. Or, maybe do the rockers first and then the exhaust. Anyway, no need to do it all at once. I've got a set of DJs, too, and have been watching this thread.

Good luck!

Hans
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'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[90weekender]

Small update.

Found NOS 2.1 pistons and liners in Europe for about $1000.

[90weekender]

I'm challenged to find cam dimensions and wear limits. Not lift and overlap...just plain old geometric dimensions.

Please let me know if you have a link.

R

[90weekender]

So I've taken the advice of our gurus Mark, Jberger and Howesight and went "back to school". I've studied the following:

John Muirs book (thanks Mark)
watched every rebuild video posted by Sanchius (and a couple old 911 rebuilds).
Read a crazy long thread about crank case oil breathing (Thanks JBerger)

David Clymer also shared his experience with running DJ pistons in an MV engine. Essentially it failed after 2 years due to detonation that he could not hear from the drivers seat.

I've also measured my engine. Below is a mostly complete map of my major engine parts and current measurements after 130k miles. Looks good, but I'm puzzled as to why I broke an oil ring.

R

Updated Engine Map:

[90weekender]

Cam lobe trouble?

Measuring in .001" is helping me see the engine components in much finer detail. Last week I inspected the cams and found these tiny cracks in the noses of lobes 1 and 2:

Is my cam junk?

Cam lobe for piston 2

Cam lobe for piston 1

The #1-2 side of the engine had a recent AMC head on it, so maybe the PO had trouble with that side.

[90weekender]

Took my engine parts to be cleaned and inspected by a machinist.

Cam could be reground for $140 but the cracks may remain. So I'm looking for a new MV cam, Here's what I'm finding:

Hertiage: "Brand-new hydraulic camshaft made from a new billet and shaped to the 2.1 Waterboxer profile.

https://www.heritagepartscentre.com/eu/025109021b-hydraulic-camshaft-for-2-1-waterboxer.html

Here in the classifieds: DH code, -3 sprocket. I'm researching the part number is compatible with an MV engine.

https://www.thesamba.com/vw/classifieds/detail.php?id=2421381

VW classic parts in DE: DH engine code, -1 sprocket

https://www.volkswagen-classic-parts.de/en/nockenwelle-9d1d40.html

[MarkWard]

I would not reuse that cam as is. Another option would be to search webcam camshafts. US company and easy to work with. You’ll need new lifters with a new cam.
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[90weekender]

Mark,

Webcam has a regrind, and does not have MV specific cams....just for "all WBX".

I'd like to find an NOS MV cam or at least an aftermarket MV-ish cam that fits my OEM spec oil pump.

GW sells their OEM style cams separate from kits, but they are regrinds.

I've found the CB cams don't work with my stock oil pump.

R

[jberger]

I may have typed previously in this thread.. but certainly in others. I'm not aware of any NOS MV cams. There are really no "dimensions" to check for reference. The only way to check a cam is on V blocks at all journals, thrust surfaces, gear flange and lobes... then you HAVE to clock it with the case, cylinder, head, rockers mocked up to determine the valve opening and closing events.. for each cylinder (though arguably 1-3 and 2-4 should be the same). Reject any cam that you're not happy with. And that includes the mythical perfect Web cam. Don't get hung up on your OE oil pump. The type one pump for flat cams is a fine replacement... plenty of reading on that.

Your engine map has #2 and #4 switched. Quick glance says that #1 and corrected #2 cylinders are out of spec. Curious if these are OE liners or replacement units of known\unknown brand. Generally OE liners are straight and round. Off brand liners can be WAY out of round and taper when new. FWIW the last OE Kolbenschmidt $1000 set I measured were within .0001" round and taper also in relation to each other.

J

[90weekender]

J,

Thanks for the engine map corrections. I'll double check that.

My machine shop says the pistons are within spec. He's measuring the OD at the bottom of the piston skirts and ID in the corresponding cylinder bores. Also, he runs a volume driven operation rebuilding VW boxer engines for all the local garages. Which means he is VERY frugal and a little too eager to reuse parts versus replacing them.

I will call Heritage and see if a "new" MV cam is in the works as they advertise on their web site. Otherwise it looks like CB 2252 and corresponding oil pump are necessary.

My pistons and liners are OE. And yes, I've seen the $1000 Kolbenschmidt sets on german vendor sites. Are they really worth it vs. GW 96mm?

[jberger]