Coil on Plug mounting plate question

[jwetering]

I'm installing a COP system on my M42 swap but have a question about how (or if) the coil mounting plate attaches to the valve cover. I'm making my own mounting plate as we speak.

The stock system involves a black plastic trim piece that attaches to a larger black plastic tray with a couple of twisting clips. That tray into place under some divots cast into the valve cover.

I get that I will lose the plastic trim piece - but do I also lose the plastic tray or do I leave it in place and my plate will attach to the tray. If I leave the tray - how is the mounting plate normally attached to it ?

If I remove the plastic tray then how will the mounting plate be attached to the valve cover ?

I have searched but this isn't clear from what I've seen and read.

The drawing I am working from for the mounting plate indicates two holes which I assume line up with where the clips attach to the tray, but I can't see how using those twisting clips would hold the plate down.

Thanks for any insight.

[iansane]

It's been awhile since I made my plate but I ditched all the plastic and used the two valve cover mounting bolts (with studs) to locate the plate.

[jwetering]

It's been awhile since I made my plate but I ditched all the plastic and used the two valve cover mounting bolts (with studs) to locate the plate.

Aha ! ....and the penny drops. That's exactly the answer.

I will thread a stud, use a washer and nut to clamp down the valve cover and then clamp the plate to the stud using washers and nuts.

Of course that's how it's done. I feel stupid now for asking.

Thanks

[bmwman91]

Yup, all the plastic stuff goes away and you also have to make some new VC fasteners to replace the 2 shorter inner ones. Harvest the rubber grommets from them. Then use some M6 threaded rod, washers and nuts to make a stack that positions the plate and coils at the right height.



What are you planning to do for wiring? Honestly, this is the most important part IMO. The stock coil wiring is long enough to reach, although you have to hack-up the PVC sheaths a bit to make it work. A lot of guys leave the wires the original length and just sort of zip tie a bird's nest into place on the valve cover. It's not ideal, but it seems to work. Just leave enough of a service loop between the chassis and engine so that the engine vibration won't be tugging on the wire loom.



If you want to make lots more work for yourself and try to do it "right", although it also carries the risk of really screwing things up if you are new to automotive wiring...only do this if you are confident with wiring and have some experience with it. I really need to make a proper how-to for this at some point!

The first time I did the COP conversion I cut off the sheaths, trimmed the wires to around the right length, re-soldered the terminals back onto the ends and then wrapped the new loom in electrical tape. It worked fine for 14 years (fun fact: I invented the M42 COP conversion), but I do not recommend that method since it makes a mess and can leave the wires prone to breaking at the terminals. This is a bit OCD, but here's how I would approach it (and how I recently did when I totally rebuilt an entire M42 engine harness). The ideal way is to get new PVC sheathing, but if you have never done wire harness work before it will be super frustrating to get the lengths right, to feed the wires and to get the rubber boots onto it. Either way, get some 99% isopropyl alcohol ("rubbing alcohol") and clean the wires well first. You get much better results that way. Also, before cutting anything, get a good look and some pics of the wire lengths going to the connectors, in particular how the shield on the center black wire is trimmed back. You want it to get as close as possible to the connector but with absolutely no risk of shorting anything (new heat shrink tubing recommended).

A reasonable alternative is to wrap the harness with good harness tape, such as Tesa 51036. Most of the stuff on eBay and Amazon is knock-off crap, so a reputable retailer is recommended.
19mm: https://www.waytekwire.com/item/2092...-Wire-Harness/
25mm: https://www.waytekwire.com/item/2092...Abrasion-Wire/

Terminals (trust me, buy extras if you have not crimped this type before and practice on wire scraps that you trim off):
x8, they go on the larger center black wire: https://www.digikey.com/product-deta...6CT-ND/6810747
x16, they go on the outer green & brown/orange wires: https://www.digikey.com/product-deta...4CT-ND/5419536

Crimpers:
I don't have these ones, but they look like they would work: https://www.amazon.com/IWISS-Profess...323722&sr=8-11

Terminal extractor kit:
I have this one and it works well, you could try one of the cheaper stamped steel kits on Amazon too: https://www.amazon.com/BETOOLL-23-Pi...323896&sr=8-15

[jwetering]

Yup, all the plastic stuff goes away and you also have to make some new VC fasteners to replace the 2 shorter inner ones. Harvest the rubber grommets from them. Then use some M6 threaded rod, washers and nuts to make a stack that positions the plate and coils at the right height.

Once the penny dropped above I got a really clear visual of how to make this happen - right down to reusing the rubber grommets. It's going to be good.

What are you planning to do for wiring? Honestly, this is the most important part IMO. The stock coil wiring is long enough to reach, although you have to hack-up the PVC sheaths a bit to make it work. A lot of guys leave the wires the original length and just sort of zip tie a bird's nest into place on the valve cover. It's not ideal, but it seems to work. Just leave enough of a service loop between the chassis and engine so that the engine vibration won't be tugging on the wire loom.

This is my plan for now.

I have a spare m42 harness and I *might* put together something more formal like what you are describing below at some point in the future (and thanks for that level of detail - it's totally appreciated) but I think I can make the simple method look and work very well.

I have pretty extensive experience with wiring, soldering, crimping and heat shrinking so I'm comfortable doing the work, but I'm not going to that level of detail on this first pass because I really want to get this project done and lord knows I have other things going on in my life. Not to say I'm going to rush it....but doing it right will add weeks to the job. I'm in Canada just getting the supplies ordered and delivered will be a bear.

The first time I did the COP conversion I cut off the sheaths, trimmed the wires to around the right length, re-soldered the terminals back onto the ends and then wrapped the new loom in electrical tape. It worked fine for 14 years (fun fact: I invented the M42 COP conversion), but I do not recommend that method since it makes a mess and can leave the wires prone to breaking at the terminals.

I may consider to do it this way - or a modification anyway. The plan would be to remove however many centimetres from the middle of the wire as necessary to make the new length correct and then splice the two wire ends together - covering with heat shrink of course. Is that what you mean when you say you resoldered the terminals to the wire end ?

And kudos for having the nouse to do this for the first time. Call me a narcissist but I would have named the mod after myself.

Thanks for the support.

[bmwman91]

Cool, yeah if you have wiring experience then it is fairly straightforward.

When I say I soldered the terminals, I meant that I took the connectors apart and pried the crimped terminals off the ends, and then mashed + soldered them on to the trimmed wires. I was a broke college student and could not find PNs for the terminals (not that I would have spent the money on them or crimpers anyway!), so I hacked a solution together lol. 14 years later, I have a lot more experience with this stuff, and a lot of my career involves knowing how to do this stuff, so I did it properly when I was building a fresh harness earlier in the year. Anyway, I would not cut them in the middle and solder. The shielded black wire would be a hassle, and you really want to keep the shield intact since the 450V flyback spikes from the coil primary make a lot of EMI. I think it would actually be less work to pop the terminals out of the connectors, cut things and crimp new ones on.

You can see some of the stuff I did in this thread, specifically posts 55, 65, 68 & 118. I really should get in there and properly document how I routed and secured the wires, as well as a list of the fasteners I used and the height of the COP plate.
https://www.r3vlimited.com/board/for...project-thread

Maybe I should have called it the bmwman91 ignition mod lol. I made a few conversion kits and sold them back in 2006-2007, but I was too busy getting my life together so I published the design and some other folks in the community started making & selling kits which was cool. I also started M42Club back around that time with a guy from Bimmerforums (user Sheepdog on M42Club who runs the server). The M42 got zero love from the E30 community at the time (the hot thing at the time was "just go find a late 318 and swap an S50 in!"), so it was really great to have the M42-specific forum at the time.

[jwetering]

Cool, yeah if you have wiring experience then it is fairly straightforward.

When I say I soldered the terminals, I meant that I took the connectors apart and pried the crimped terminals off the ends, and then mashed + soldered them on to the trimmed wires. I was a broke college student and could not find PNs for the terminals (not that I would have spent the money on them or crimpers anyway!), so I hacked a solution together lol. 14 years later, I have a lot more experience with this stuff, and a lot of my career involves knowing how to do this stuff, so I did it properly when I was building a fresh harness earlier in the year. Anyway, I would not cut them in the middle and solder. The shielded black wire would be a hassle, and you really want to keep the shield intact since the 450V flyback spikes from the coil primary make a lot of EMI. I think it would actually be less work to pop the terminals out of the connectors, cut things and crimp new ones on.

You can see some of the stuff I did in this thread, specifically posts 55, 65, 68 & 118. I really should get in there and properly document how I routed and secured the wires, as well as a list of the fasteners I used and the height of the COP plate.
https://www.r3vlimited.com/board/for...project-thread

Maybe I should have called it the bmwman91 ignition mod lol. I made a few conversion kits and sold them back in 2006-2007, but I was too busy getting my life together so I published the design and some other folks in the community started making & selling kits which was cool. I also started M42Club back around that time with a guy from Bimmerforums (user Sheepdog on M42Club who runs the server). The M42 got zero love from the E30 community at the time (the hot thing at the time was "just go find a late 318 and swap an S50 in!"), so it was really great to have the M42-specific forum at the time.

All right - I'm glad I posted now. Thanks for preventing me cutting one of my wires in the middle and discovering shielding. Not that I was planning to - but like you I'm a guy who prefers to have wires the correct length. My plan is now firm to run the wires at their stock lengths. I will deal with any excess length without cutting and soldering for now. I have both time and an extra wiring harness to play with.

So the next question is which coils to buy. I am preferring these because they will fit into a round hole and because the heads look less bulky than some of the other options....no doubt you will have an opinion. I'm looking for good enough or better - my build will be nice but not yet to the level you are working at.

https://www.rockauto.com/en/moreinfo...83230&jsn=2776

I am looking at that part number: 121 375 99 219

My build thread is here. It's an m10-> m42 swap so yeah I'm going to a lot of effort to keep another 4 cylinder on the road.

Apologies in advance for not being up-to-date and for the long drawn out but ultimately unsatisfying wiring harness discussion at the end.

https://www.r3vlimited.com/board/for...10-to-m42-swap

Cheers

[bmwman91]

Just about any coils should be fine. I don't think paying extra for brand-name ones really matters. URO is sort of questionable, but I'd bet you will still get tens of thousands of miles out of those coils.

I'll check out your swap thread. It's always good to keep some 4 cylinder E30's on the road!

[downforce22]

You can see some of the stuff I did in this thread, specifically posts 55, 65, 68 & 118. I really should get in there and properly document how I routed and secured the wires, as well as a list of the fasteners I used and the height of the COP plate.
https://www.r3vlimited.com/board/for...project-thread

Maybe I should have called it the bmwman91 ignition mod lol. I made a few conversion kits and sold them back in 2006-2007, but I was too busy getting my life together so I published the design and some other folks in the community started making & selling kits which was cool. I also started M42Club back around that time with a guy from Bimmerforums (user Sheepdog on M42Club who runs the server). The M42 got zero love from the E30 community at the time (the hot thing at the time was "just go find a late 318 and swap an S50 in!"), so it was really great to have the M42-specific forum at the time.

I didn't realize this, thank you for coordinating a place for m42 knowledge. I didn't like the m42... up until I drove one, with its rev happy nature and 2nd gear gearing. I figured I would run it until it blew up and then engine swap it. I found the hot start issue on m42club which solved the main problem I had with the car. Soon the engine even overheated for 2 laps at the track when the alternator belt came off the water pump. With some new coolant it has been fine ever since. Getting 28+ mpg, no valve adjustments, no timing belt changes, or spark plug wires/cap/rotors to maintain all sold me on the m42. With a lightweight flywheel it is a fun and capable car. And now i've put over 31k miles on that engine with unknown history.



Now I am building an m42 powered 84 318i track car. So why not make that road legal too?

[jwetering]

OK - thought I'd post photos of the finished product. I might update my build thread show to show more....

some tidying up to do at the far end still....but it will be very good.

[iansane]

Looks good!

[bmwman91]

Pretty good! I can't quite tell from the pic, but did you wrap the wires/sheaths with tape?

[jwetering]

Pretty good! I can't quite tell from the pic, but did you wrap the wires/sheaths with tape?

I used a wrapping sheath - can't tell you what it's called but it's woven nylon type of thing, like those chinese finger trap things. Looks sharp - wires are well protected.