Author Topic: M42 budget build (Read 11368 times)

P Zero · « **Reply #15 on:** May 05, 2008, 01:11:41 PM »

I started work on the engine in the past week. I got it up on a stand at the beginning of the week, I stripped all the ancillaries and loom, then gave it a good degreasing.

The plan is to get the throttle bodies, coil on plug conversion, etc sorted before I rebuild it, so its all ready to be refit during the buildup.

So, today I started fitting the ITB's. I've used the first and third pairs because they have the mounting points for fuel and vacuum rails. After trying a test fit of the rails, it looks like I'll have to heavily modify the existing 4 or 6 cylinder rails, or fabricate something from scratch.

I I did shorten the throttle bar though. It seems there may also be a problem with the throttle postition sensor because it clashes with the head. For just now, I have removed it and its bracket.

As mentioned in other threads, only the bottom holes on the bodies match the head, so I'll have to do something about that. Not sure what yet though...

Sorry about the quality of the photos, I'll get some better ones!!

ClodKing · « **Reply #16 on:** May 05, 2008, 05:56:24 PM »

What about a spacer of some sort?

I know it would cost you more money, but I think it would be the easiest way.

How close in proximity are the bolt holes (all three I mean).

If you were to use a piece of metal (aluminum most likely) that would clear the head of an allen screw, or bolt (or torx

), and then bolt the TB's to the spacer.

If you get measurments I'm sure any machine shop could make one for you a fairly cheap price. It's not like it would be a fantastically difficult piece to design, or make....

That's what I would do, but there may be other ways that are more cost effective.

ClodKing · « **Reply #17 on:** May 05, 2008, 05:58:25 PM »

It may also give you enough clearance for you throttle position sensor...

P Zero · « **Reply #18 on:** May 05, 2008, 06:29:24 PM »

I had wondered about a spacer, but I dont think it would be the best. It would only need to be about 10 - 15mm thick, but the bolts holding it to the head would be in the way of the location you would want the new threads for the itbs to bolt to.

I've also been reading through this thread (http://www.bmwowner.com/forum/viewtopic.php?f=17&t=19510&st=0&sk=t&sd=a) which indicates that the injector jet may not be at the best angle when using a spacer

swiss318is · « **Reply #19 on:** May 06, 2008, 04:50:48 AM »

just a question.. is it possible to cut all the bolt holes from the ITB and weld it on a spacer that fits on the head??

P Zero · « **Reply #20 on:** May 06, 2008, 07:36:46 AM »

Quote from: swiss318is;48712

just a question.. is it possible to cut all the bolt holes from the ITB and weld it on a spacer that fits on the head??

Thats not a bad idea, it would certianly look great. They really need to be as close to the head as you can get them though. In my opinion, one of the problems with using these itb's is that when mounted on the head, the injector is further from the valves than with the standard setup. The throttle body is already oval shaped by the time it reaches the head, but ports on the head have the cutout for the fuel flow from the injector on the standard inlet tract.

Not sure if that makes much sense, but I'll try and get some photos later to explain better.

P Zero · « **Reply #21 on:** May 06, 2008, 05:50:34 PM »

Played around a bit more tonight. I tried the fuel rails from both M42 and S50 for size. Its definitely best to use the S50 fuel and vacuum rails. I can still use the M42 injector connection box.

The fuel and vacuum rails will have to be modified, obviously they are 2 cylinders too long. They will need to be shortened and the brackets at the front end moved back to compensate for the missing pair of itb's. The vacuum rail connection also needs to be moved, because it usually pokes through between the middle pair of itb's but the two end pairs, which I am using, have the mounts for the rails in the way. The photo above shows everything mounted up using the centre itb instead of the front one just so everthing would fit. I will need to use the front itb though because it has the rail mount and the tps mount. It may be easier to fabricate the fuel and vac rails from scratch rather than mess around modifying these ones.

The photo below shows the tps clash with the head. This can be easily sorted by making up a new slimmer bracket from sheet aluminium that will fit in the gap.

I also had a look at the port shapes a bit more while I was in the garage. It looks like the size is just the same, however, there are two problems here. The centre mounting hole is not quite the same height, so the bodies need to be pushed as far up as they will go to get the vertical alignment correct. The second problem, as I mentioned in a previous post, is the cutout in the port for the injector jet. On the M42, this cutout begins in the lower inlet manifold, and continues into the head. On the itb's, this cutout begins and ends in the itb itself. I think it could be left as it is, but surely it would be better to try and get the flow of air and fuel as smooth as possible?

P Zero · « **Reply #22 on:** May 06, 2008, 07:05:35 PM »

If anyones interested, heres a piccy of my sanctuary

nomad · « **Reply #23 on:** May 07, 2008, 12:48:50 AM »

Do you have someone who can weld aluminum?

Looks like an option would be to get those on a mill and take a good .125" off the thickness of the flange face. This would bring the injectors down closer to the port opening. You can machine off the ITB bolt tabs and weld on tabs in the right position.

OR

You can cut and weld the ITB pipes onto the OEM flange and use the OEM injector holes.

P Zero · « **Reply #24 on:** May 10, 2008, 06:57:07 PM »

Quote from: nomad;48802

Do you have someone who can weld aluminum?

Looks like an option would be to get those on a mill and take a good .125" off the thickness of the flange face. This would bring the injectors down closer to the port opening. You can machine off the ITB bolt tabs and weld on tabs in the right position.

OR

You can cut and weld the ITB pipes onto the OEM flange and use the OEM injector holes.

I'm definitely thinking of having the flange face machined so that the injectors are closer to the ports, but I am concerned about it getting expensive.

Can anyone explain to me where the various connections on the vacuum rail/balance bar should connect up to? I know the large connection on the left goes to the idle control valve, but there is a smaller connection in the centre, and an even smaller one to the right.

P Zero · « **Reply #25 on:** May 11, 2008, 02:09:35 PM »

Didn't do much today. I got distracted by the guy in the garage next door with His Caterham. We went about 30 or 40 miles which was great fun!

I found out what the second connection on the vacuum rail is for. The brake servo

I should have realised really. I am assuming that the third small connection is just a drain off or something.

What I did do was shorten the fuel and vacuum rail. All I did was cut the two centre itb connections off each bar, and I'll get someone to weld them back together for me. The fuel rail will be complete at that point, but I will need to have the connections for the brake servo and the idle control valve added to the 'new' rail.

I also cut off the rearmost part of the mount for the throttle position sensor. It seems to be more than fine with only one bolt holding it on.

BrandC · « **Reply #26 on:** May 12, 2008, 12:11:17 PM »

Quote from: P Zero;49089

Awesome looking! Is this the stock M42 fuel injector rail? How available are these ITB's from M3's? I'm VERY interested in following the same route you are going...

P Zero · « **Reply #27 on:** May 12, 2008, 02:33:05 PM »

Quote from: BrandC;49150

Awesome looking! Is this the stock M42 fuel injector rail? How available are these ITB's from M3's? I'm VERY interested in following the same route you are going...

The top rail is the M42 injector control bar, the middle rail is the cut'n'shut M3 fuel rail, and the lower rail is the M3 cut'n'shut vacuum rail.

The ITB's come up on ebay over here fairly often. I got mine for �100gbp, but I think I got a bit of a bargain as they seem to go more regulary for around the �200 - �300gbp mark. Heres a set - http://cgi.ebay.co.uk/BMW-e36-evo-m3-throttle-bodies-fuel-rail-injectors_W0QQitemZ130221210866QQihZ003QQcategoryZ10374QQssPageNameZWDVWQQrdZ1QQcmdZViewItem