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  #11  
Old 12-06-2014, 12:40 PM
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Tito,

On the M20 engine you should not only do the timing belt but both the tensioner and the water pump as well.
Extra parts but you save labor. If your water pump fails in 6 months, you have to pull all of the front engine stuff, including timing belt to replace. Oh, and buy a factory pump.. the after market stuff has been junk lately.
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  #12  
Old 12-06-2014, 05:28 PM
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Paul, thanks. Do you have a recommended brand for the head gasket? Other than the bmw one?
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  #13  
Old 12-06-2014, 05:48 PM
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Iím ALL for learning how to do things yourself, but the head may not be the place to start.

On the one hand, almost anything will work and run. On the other hand there are a few very important things that can lead to quick failure.

Unfortunately most home mechanics donít have the tools necessary to do a correct job on a head.

Depending on condition, some seats may need to be cut. You want them all at the same depth, so often this means either cutting them all, or replacing a few seats. And every time a seat is cut, the valve moves farther up inside the head. This leads to shrouding of the valve and a drop in compression which are both bad for power output.

Then you also want all the stems at the same height. So you need some way to measure this and also to grind the stems so you have the correct finish when they are done. This is normally one of the functions of a valve grinding machine. If you donít have a valve grinding machine, you arenít going to get an adequate job.

The valve grinding machine is also what cuts (grinds) the angles on the valve as part of the valve job.

Spring tension needs to be set for each spring. Too light tension and you get valve float. Too heavy and it takes way more power to simply push the valve open. Both situations are extremely bad for the valve train components and lead to early failure.

There are special fixtures to test valve spring tension, and then you need a selection of shims to be able to adjust it. Donít have the tool or the shims and itís not getting set.

If you have the machine shop do it and then you put it all together, you have to make sure that you donít get anything mixed up and each piece goes in the correct location.

While the pistons may go up and down and make the car move, the head is really where all the power comes from and where most of the important work is done.

So the head really isnít a place where you want to be learning on your own. Especially if itís your stuff!

You would be much better off just having a competent shop do the head for you and then you simply reinstall it on the engine. Unless you enjoy working on this stuff over and over more then you enjoy driving it.
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  #14  
Old 12-06-2014, 08:44 PM
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I totally agree w/everything above except not doing it yourself. for one thing unless you specify the machine shop blue prints your head (and provide details of what that means) you will likely not get that detail. Testing spring tension, stem length etc. etc. is crucial for high performance heads but most shops don't specialize in that kind of work. Remember 98%+ of productions cars aren't driven on the track no mater what the marque. Get yourself a good blue printing book or at least do some research on line. All can/will be reveled w/a little research. Report back w/reference so others may learn from your experiences! Keep posting, everyone learns when one learns and shares!!!
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  #15  
Old 12-07-2014, 05:20 AM
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Ok. Sitting in the lounge in Frankfurt airport searching for some valve spring info.
Bmw e30 m20b25 engine valve spring specifics:

Installed height 1.495 inches. 68 lb
Compressed height 1.04 inches 164 lb

Anyone have a valve spring tester I can borrow or come over and use? Maybe ft belvoir hobby shop has one.
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  #16  
Old 12-07-2014, 11:19 AM
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Quote:
Originally Posted by 86911TLCAB View Post
Paul, thanks. Do you have a recommended brand for the head gasket? Other than the bmw one?
I would recommend OE, Goetze, Cometic, or MLS. The last two are more performance oriented and thus are a few bucks more. The factory head gasket or the Goetze should be sufficient.

You should probably buy a gasket set as it will include everything need to put the top end together like valve seals, intake and exhaust gaskets, and the front timing cover gaskets. Try Bavarian Autosport or Turner Motorsport for these items.. also the dealer pricing may be pretty good too with your BMW Club discount
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  #17  
Old 12-07-2014, 02:29 PM
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Quote:
Originally Posted by 86911TLCAB View Post
Ok. Sitting in the lounge in Frankfurt airport searching for some valve spring info...
See, everyone always estimates Tito's capabilities and amazing drive when it comes to this stuff. All this namby-pamby BS about needin' this, and gettin' someone to do that... But Tito steps up to the plate and actually flies to Germany to get all the knowledge he needs to knock out this project directly from the horse's mouth!
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  #18  
Old 12-07-2014, 02:42 PM
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Paul thanks will do so.

Dave, thanks for the vote of confidence. It can't be that hard to do this. Plus as long as it runs after I put it together I will consider it a success.
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  #19  
Old 12-07-2014, 03:39 PM
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Paul, Bavarian has a gasket kit, but doesn't detail who manufactures the head gasket. Do you know if it is Goethe or the victor Renze one which I keep reading many are having issues with early failure?
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  #20  
Old 12-07-2014, 08:48 PM
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Quote:
Originally Posted by 86911TLCAB View Post
Paul, Bavarian has a gasket kit, but doesn't detail who manufactures the head gasket. Do you know if it is Goethe or the victor Renze one which I keep reading many are having issues with early failure?
Not sure who they're using these days but Bavarian usually does they're homework and sells decent stuff. They've been around a while.. you can also check BMP in Texas.
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