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Hey guys just trying to get some input and suggestions. I purchased my 68 bmw 2002 with the 12a already swapped in it. As far as i know it is stock ports by the sound. Running a weber 44idf downdraft setup and the ignition is setup with msd and blaster coils. Still running through the distributor. I can get the car to start and run with effort but it is not running correct. Down on power and seems to be a mix of timing and carb adjustments. Before i play with the carb im trying to get the timing 100%. I have pulled the cas/dist and restabbed with the marks aligned while having the crank pulley set at tdc. Problem is when trying to use the timing light the leading and trailing marks are no where even close to the actual mark. Also kind of wondering about the vac advance since that is unplugged.
Have any pics...of car? Had a 2002Tii til just a few years ago,very cool cars. Would suppose someone has removed the v-belt pullies at some point and failed to reinstall in correct orientation. They can be installed in any one of four positions,of course only one is correct. There are a couple ways to find tdc on your engine. My preferred method is to remove inspection plate covering flywheel on right side of engine & turn engine by hand until flat side of flywheel is even with rear iron. This is tdc for front rotor. Remove four 6mm fasteners and remove v-belt pullies and orient marks to the pointer on front cover and reinstall. Remove dist. and reinstall as previous with marks aligned. Shold be able to start engine and set timing correctly.
Regarding vacuum advance, is normally used with a ported vacuum source and most Webers of that design have no ported source of vacuum cast into them. Some have a manifold vacuum nipple on the body but that is not suitable for vac advance duty as it over advances ignition timing at idle. Best to leave vac advance canisters uncapped/open to atmosphere.
Once you have it running better consider doing a direct fire conversion on ignition system,lots of benefits to this,lot of threads here for how to,just search DLIDFIS. In doing this recommend replacing MSD box with GM HEI ignitors and using blaster coils for both leading rotor ignition.
The MSD box can fire both coils for leading ignition but since the coils have to share the output from the MSD the spark produced is not as strong as it could be. Engine only needs leading ignition to run, trailing can be added to help clean up emissions and lessen HCs from tailpipe.
Thanks for the quick reply! I have read alot on what you are saying with the crank pulley being put on wrong so that is a great start. I will snap some pictures tonight and post them up. I couldnt pass the car up for 1k
So i checked the timing with doing the flywheel like you said and it is perfectly lined up to the mark on the right of the pulley. Doest make sense that it doesnt show up on the timing light? Also snapped a pic of the setup so baby i can get better input
Thanks for the pics,so engine timed mechanically properly. Likely the problem is in the ignition primary electrical circuit. Suspect the wiring from dist.pick ups (polarity) to MSD box(es) is possibly reversed.
Question: Can you see the timing marks with the timing light,how far from pointer are they,in front or behind(advanced or retarded)and where is the distributor lockdown bolt in relation to the adjustment slot? Can you get a pic of that?
I doubt i will be able to get a picture of that but in relation the marks are about 3 inches to 4 to the drivers side...i dont remember which way that is full advance or full retard. Any way of checking the wiring or any schematic for this?
Pic was asking about was relationship of lockdown bolt to adjustment slot. When timed properly it should be midway in slot. When you had engine at tdc,did dist rotor look to be in same position as pic i posted? Rotor should be under terminal in dist cap for rotor #1. Check for this first.
Ok,can you take the rotor off and take a pic of pickup coils underneath? I only see one set of leads coming out of distributor going to the Msd box(es). It appears there are cut wires poking out of that tape,can you untape and take a pic? There should be two pairs... can you trace the wiring from the distributor to the boxes and show some pics of connections there?
The ignition wires coming to/from dist.cap show leading and trailing coil and spark plug wires,but as noted,only one set of pickup leads coming from distributor to boxes. This wiring needs to be investigated. If both boxes are wired from one pickup signal then leading and trailing ignition are firing at same time which is pointless,AND it's possible the polarity of pickup connections is reversed likely contributing to the out of spec timing marks. Really hard to diag long distance so pictures have to show as much as possible. Will look in on this thread tomorrow.
Ok,where to start...the pick up coil toward front of car is leading ignition pickup,the one to the rear is trailing. Trace the leading pick up wiring back to identify which MSD box it's connected to. The car will start and run on leading ignition only,for diagnostic purposes,disconnect trailing pick up coil harness where it connects to trailing MSD box to disable trailing ignition.
You will need to untape the connections made to leading pick up coil to verify wire color coming out of pick up. The pick up is a low voltage AC generator that outputs a varying amplitude/frequency signal the ignition module(in your case MSD box) uses to determine dwell/coil saturation and to an extent timing. There is a + &- side of this generator and correct polarity needs to be observed when modifying wiring.
If this wiring is reversed,the generated signal output will fire the ignition coil at incorrect time,changing firing event many degrees. Your comment about where timing marks are showing up leads me to believe this is the case. Start and warm engine and check timing marks with timing light again to verify leading ignition is as before. Yes? Shut down and find the connection for pick up leads at MSD box. From memory the green wire coming from pick up is the + side of signal generator and should go to the purple or violet wire at MSD box. The red wire at pick up is - and should go to green wire at MSD box. I believe this is correct,working from phone as i'm on the road til later. Find these connections at MSD box and switch them and recheck timing and see if not closer to where it should be. Post back results.
In looking at your MSD boxes,i can see one is a 6AL,the other is different,can't make out what model it is. Look up Complete MSD Wiring Manual-MPS Racing online and search for your model box. There is a Toyota branded relay i see hanging upside down in harness near ignition coils,is that part of ig.system wiring?
So according to the msd diagram for running 2 6 series units..the violet coming out of the unit goes to the + green wire coming out of the trigger. The green coming out of the msd - goes to the purple wire coming out of the trigger. This will mean i will have one unit for leading and one for trailing.
Are you at car now?...pick up coil in distributor,you have two,they are identical, have a green wire=+ and a red wire =--. The lead in to the MSD box has violet+ and green-. The green wire FROM dist. Should be connected to the violet MSD wire. The red wire from dist should be connected to green wire at MSD box
Are you at car now?...pick up coil in distributor,you have two,they are identical, have a green wire=+ and a red wire =--. The lead in to the MSD box has violet+ and green-. The green wire FROM dist. Should be connected to the violet MSD wire. The red wire from dist should be connected to green wire at MSD box
Yeah, it's easy to remember because it's backwards.
Man that wiring is hacked, I almost don't feel bad about my wiring now lol
07-06-17, 10:13 AM
12A timing in bmw 2002
