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1967 404 Unimog (Belgian), 2010 Ford Fusion Hybrid
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Discussion Starter · #1 ·
There has been a lot of discussion here and elsewhere about getting more power out of the M180. Some of these discussed increasing the compression. Three methods seem like they show promise.

(1) Swap the head for one from a sedan

(2) Shave the head

(3) Use a thinner head gasket

I don't want to do #1 because it's probably expensive and difficult; I'm a cheap bastage and would probably mess up anything complicated anyway (please note screen name).

I've read that #2 won't work. I've seen a picture of a sedan head and the underside is almost completely flat. I'm assuming the 404 head is similar and that's why milling a bit off won't work.

How about #3? Does anyone know the thickness of the standard gasket? Is there any interference issue if you make it really thin? Has anyone tried this?

Thanks for any advice.
 

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1957 404 FireMog
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not worth the time and effort

DDB,

The low compression MOG head has recessed chambers above the cylinders. More space = smaller compression ratio. The amount of compression increase gained by either shaving the head or reducing the head gasket thickness would be negligible for the amount of work needed to accomplish either.

Regards,

Jeff
 

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1967 404 Unimog (Belgian), 2010 Ford Fusion Hybrid
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Discussion Starter · #3 ·
Thanks for the reply.

I understand what you're saying about the recessed chamber in the head resulting in lower compression. Do you know why shaving the head or the thinner gasket has little effect?

Also, does anyone know how thick the stock gasket is?

Thanks.
 

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1957 404 FireMog
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volume reduction is not significant

The height of the stock head is 84.8 to 85 mm. The minimum height recommended is 84 mm. that means the maximum amount recommended to remove from the head is 1mm
(1 millimeter = 0.039 inch that sounds right to me).

The bore = 80mm. The stroke = 72.8mm. The stock total compression space is 48200 – 50200 cubic mm. Because of the shape of the compression space in the head it would take calculus to determine the actual amount of volume reduced by removing 1mm from the head but it would not be enough to significantly increase the compression ratio. The total compression space with the HC(8.7:1) head is 36400 - 37400 cubic mm.A reduction of about 25%.

BTW. It's the same amount of work to install a new head as it is to replace the head gasket.

A stock head gasket is about 15mm thick. I would assume it gets compressed to less that half that when the head if fully torqued.
 

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Discussion Starter · #5 ·
Great info, thanks.

I see what you're saying about shaving the head.

The sedan heads I've seen pictures of look like they won't fit the stock intake/exhaust manifold. That's what I meant my difficult and expensive. I don't know that for sure, of course.

That gasket thickness actually sounds promising. A thickness of 7 mm when compressed is ~.275 inches. Using a .022 copper gasket seems like it would help a bit. I'll try and do some figurin' on that...

Do you know how close the top of the piston is to the top of the block at TDC? Removing the engine to shave the block is way more than I want to fool with, I'm just curious.

Thanks again for the help.
 

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63 UNIMOG S404.115
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Removing the engine to shave the block is way more than I want to fool with, I'm just curious.

Not the worlds expert on M180's but as a general rule when you start considering machining heads or blocks to gain HP as opposed to removing imperfections in the surface then you need to consider a number of other issues that are defined by the engine design; timing chain tension, water jacket location, deck height et al.

Pretty sure that in the collection of archives and sites around, trying to extract HP from the M180 has been well and truely researched. Somewhere I've seen a complete list of HC heads that will fit the M180 and also a list of MB engine swaps that are bolt in (although most everyone mentions that it takes far longer than a straight swap when you have to grind oil pans etc for clearance).

Completely agree with Dog Taxi that you may as well swap the head for a HC version as you'll more than double the HP increase available from machining the LC head and it is the same spanner effort.
 

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1957 404 FireMog
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The hc head and the lc head are the same except for the size of the compression space so the manifolds match up. In fact you could go with dual carbs on the hc head as the flow through will support them. I have seen some propane conversions with dual carbs. I don’t know anything about switching to propane. Maybe someone who has done it could add a little knowledge here. What are the advantages/ disadvantages? Does the propane stay a liquid until it gets vaporized in the carb?

As far as having the block shaved, machine shop time around here is not cheap. You could probably buy a head for what it would cost to shave a little off the block.

Tony,
I think the M130 is a direct replacement for the M180. Even the oil pan form the mog M180 can be swapped right over. The M130 was in some pretty hot sedans and had enough flow to support dual 4 barrels with HP rating in the mid 200s.
 

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1967 404 Unimog (Belgian), 2010 Ford Fusion Hybrid
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Discussion Starter · #8 ·
Thanks for the advice fellas.

There is a Ponton head on eBay right now. It's got some potential issues with cracking around the valves, but I did some reading and it seems that aluminum cylinder head repair is possible. The intake/ exhaust ports are round (I've seen others that were square), and with what you said about things fitting I bet this would work.

Just to be clear, HP increase is not really what I'm after. I'd like to increase fuel economy more than anything. So far the best I've been able to achieve is 10 mpg on the highway with the rear canvas off (8 mpg with it on). Don't get me wrong, a little more power would be fine, it's just not my main concern right now.

Thanks again for the info.
 

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I think the M130 is a direct replacement for the M180. Even the oil pan form the mog M180 can be swapped right over. The M 30 was in some pretty hot sedans and had enough flow to support dual 4 arrels with HP rating in the mid 200s.
Hi Jeff,

Externally, yes. Devils in the detail. I've sucked a few comments made by various MOG experts from the net to illustrate the additional work needed to effect the swap. I'm staying with the LC M180 so I won't need to get involved in this myself. Makes interesting reading though.

"Engine Block - use the newer M130 motors because they have better cooling characteristics.

Flywheel - It is preferrable to get one of the "thick flange" flywheels to work with. The holes in the flywheel for the stretch bolts will need to be drilled out to 12MM. The flywheel itself will need to be balanced. Balance the flywheel along with the crank.(A Huge amount of material will need to be removed on the oposite side of the "half-moon" on the flywheel. The half moon was designed to balance the 2.2 crank.) You will also need new flywheel bolts in order to match them up. MB Part# 108 990 04 19 x 6 - pricey at $15-20 each. The stock 2.8 bolts are too long, the 2.2 bolts are too short.

Oil Pump - the pressure relief valve on the 2.8 pump does not clear the front of the Unimog Oil Pan. (The Unimog oil pan must be used in order to maintain the rigidity with the long bellhousing.) You can remove the pressure relief, cap the hole, and screw it into the front oil galley. The engine works great with one pressure relief.

Oil Pan Mod - The stock 2.2 pan does not clear the rod bolts. You must grind the pan until the bolts clear. There is a lot of material on the pan, take off 1/16-1/8th of an inch. Depending on which oil pan you have, you may need to enlarge the rear main seal groove in the oil pan. All 2.8 liter engines use a larger rear main seal. It has been rumored that some of the later M180 2.2 liter Unimog oil pans had the larger rear main seal. Best bet is to take your sedan M130 oil pan and the Unimog M180 pan to a machinist to iden/deepen the rear seal groove to match. Otherwise, you will be using a wider seal in the block and a narrower one in the oil pan.

Alignment Dowels - (These are the dowels that align the engine to the bellhousing.) The 2.8 alignment dowels are much larger in diameter than the 2.2 dowels. Have the machine shop remove the 2.8 dowels and order the proper ones from your dealer.

Front engine mount, pulleys, fan, water pump,fuel pump, distributor, oil filter housing, tensioner, generator, starter, can all be used from the 2.2 motor.

Use whatever manifold/exhaust that suits. Fabricate your own throttle linkage so both carbs open at the same rate."

Cheers and I acknowledge the various authors of the snippets above

Tony
 

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LAND ROVER 90 / DISCOVERY BOTH FITTED WITH TWEEKED PERKINS PRIMA ENGINES UNIMOG 404
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This may be a little late but has any one considerd redusing the size the conbustion chamber with weld then remachining. as to fitting lpg mine runs stright gas yousing a impco mixer ,only had starting problem once was -10 solved with flask of hot water over gas vaporiser .
 

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