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Mofoco VW heads

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Pretty sure aeroconversions shipped mofoco heads in parts kits for a long time. they do not any longer tho, not sure why.
 
I'm running a pair of 041s that seem to be doing alright. My first Mofoco heads, 042s that came with the kit from GPASC, were duds but that's ancient history. You'll have some remedial cleaning to do, a common problem with many suppliers from what I've read.

Ed
 
thanks , i've been having problems with the heads coming loose and trying to fine a cure. i've trued everything, thought these are made with better aluminum
 
Somewhere I heard that Mofoco's castings come from Eck foundry in Wisconsin, which has a good reputation. Can you tell whether the studs or nuts are turning?
 
A friend of mine told me they machined his head to accept one of the lower cylinder steel spacers. Does away with the thin wall digging into the aluminum... just a thought..
 
Where did your friend ge5bthe steel washers? I’ve been thinking the same thing with the steel cylinder digging into the head which causes the head to loosen .
 
The thick shims that go under the cylinders (stroker motors) I'll call him and find out what thickness he used..
 
Kinda curious. Don't you have to have shims under the cylinders in order to set the deck height?

I had to re-torque the heads on 3 of the 4 25hr inspection/oil changes i've done since I bought the plane. This last one, the torque held on every stud except the upper aft one at the #4 cylinder. And, it only moved less than 1/4 turn.

Do you have the 8mm studs in case-savers?
 
The left rear cylinder head as seen sitting in the plane is the one that’s always loosening up. I have replaced the 8 mm studs , nuts , washers on the whole airplane, 4 of us in my area have vw engines of a Revmaster, areovee, Great Plains and we’ve all had the same issue from heads loosening up. I can only fly maybe 5 hours before having to retorque the heads . Friend of mine built a new vw engine in his Sonex and just had to put it down the other day , he is done with the vw engine . So any ideas , I’m open to them .
 
From the previous times that the cylinder has done , even had too dead stick it into a airport due to the head coming lose and losing compression . I’m hahave been putting this out for people to check since 4 of us have had the same issue .
 
You don't hear about this problem with earth-bound high performance VWs. The only significant difference that I can think of is that the ground crawlers have fans driving cooling air over their heads and they all use identical cooling shrouds. In contrast, our engines are at the mercy of our individual engine cooling designs and the quality of our installations.

I have to think about Fred and those who have thousands of hours flying VW engines without this issue. Everything I have read points to head temperatures and deformation of the cylinder mating surface. It would be nice to have a record of the head temperatures (measured at a common location) for the cylinders that are experiencing this issue.

Chucker
 
I'm a newbie. And, no expert by any means. So, please don't put much weight on my attempt to contribute. But, I was really concerned with this (and concerned I was gonna screw something up) when I did the first oil change/25hr inspection on 994SP's engine.

I was reading something some time ago. I can't remember where I saw it. But, guys were having trouble with the cylinder heads getting too hot. Turns out, the bottom tins hadn't been installed. The cylinders were actually deforming the heads causing the loss of compression and loss of torque on the studs.

I read another blurb on one of the VW sites that was talking about guys putting copper gaskets in the fly-cut recess on the heads, which wasn't allowing the heads to be torqued properly. As I understand it, those heads don't take any gasket, as they are designed so that the cylinders fit into the recesses and self-seal.

Another one where head studs were loosening was where someone was using an older case with 10mm studs. The studs were literally pulling out of the case. All the aero-conversion kits now use the newer universal cases with 8mm studs with case savers installed during manufacture.
 
Well I know you aren’t contributing, but only concerned. I’m just saying is you might want to keep an eye on the torque of the heads i have the cool tins on my engine and all my temps are within limits , it’s just the heads are coming loose for some reason , a lot of engine gurus at my airport have brain stormed on why this is happening .
 
BP,
Sorry to hear of your Cylinder torque woes.
The engine builder for "The Ultimate 1835" that graces the nose of 994SP had built numerous Aero VW's over the years including VW racing experience. The Spec sheet reads like a dream list of aftermarket VW accessories and parts but in short, it's dialed in. When I visited him to purchase the engine, he informed me that stroked crank engines with higher compression will have cylinder torque issues. He was a firm believer in the 1835CC/ 7.0:1 compression/forged 69MM VW crank and oversize case nuts/washers being the optimum combination for reliability. It appears this is holding true with Kenny's experience so far. The builder might be able to help diagnose your issue.

If you're interested, I can send you his contact information via PM.

V/R
Smokey

PS: Ultimate 1835 Specs:
Great Plains 1835cc Engine Kit 92mm bore X 69mm stroke. (60HP) Great Plains Diehl Alt Case Slick #4316 Magneto and Harness. 
Zenith #1821 Carb with cockpit adjustable mixture control
 Forged 69mm VW crankshaft ground to .010" undersize and balanced to 1/100th of a gram by Gene Berg Enterprises
 Piston and Rod set matched to closer than 1/10th of a gram. 
Mahle 92mm Cylinder and Piston set with Teflon wrist pin buttons. Total Seal compression ring on each piston 2nd ring (prevents blow-by, keeps oil cooler and cleaner)
 3-Angle valve job and matched valve springs by Fumio Fukaya (Best VW cylinder head man on the planet)
 Manley Stainless Steel valves
. 4130 steel pushrods (each matched for perfect rocker arm geometry) Gene Berg Rocker Shafts (with shims instead of spring clips)
Laser hardened valve adjusting screws
 Blueprinted oil pump
 Rev-master Fuel Pump Drive Adapter (driven off oil pump)
Full Flow oil filter
 Compression set at 7.0-1 Over-Sized engine case nuts and washers (VW racers have found this doubles case life)

 
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