doug73cs

I've had this http://sdsefi.com in my '73CS and very happy with it. Nice not to need a computer to do the set up. Lot's of local '02 cars and racers using it. Very good tech support as excellent install manual. Excellent web site with lots of info that will help you regardless of what system you eventually but. HTH

Thanks to all - question answered. The springs in the CS are the same configuration as the '02 - as in linear. Doug

I have been in discussion with two providers on 8" coil over spring kits to replace my ST front springs for my 73CS. Both are in agreement with the replacement spring rates - 300 to 325ft/lb to replace the ST springs 265ft/lb. I don't want a significant change to the stiffness as much as the ability to adjust the ride height. I'm curious as to why higher rated springs for coil overs? Any informed advice on this appreciated. Doug

I said I would post my conclusions when this was sorted so here it is - spark plug wire set. At the end of the day the single biggest factor was a set of 3 year old plug wires that I replaced with OEM type Bosch. All of the hesitation and sputtering accelerating from idle to cruise is gone, WOT is smooth and consistent from 3000 to redline (in the mid 12's A/F ratio) and cruise at light constant throttle is slightly lean (mid 15's A/F) until engine load increases and the A/F responds appropriately. Still running one grade hotter plug which I may leave for now. When this all started I was jetting 50 150 185 and now 45 140 185. This was probably a contributing factor to improving the "performance" of the engine. The one thing that needs attention is the richness at idle (A/F in the mid to high 11's) that I'll try to lean out a touch but if it has to stay rich to run right - so be it. Thanks to all for the comments and suggestions. Doug

Running out of options here. Tomorrows work includes: Confirm correct valve adjustment Compression test all cylinders ( curious about the numbers anyway) Swap in old dizzy cap to compare Confirm all plugs have good spark (done once - do again) Test #1and #2 wires by switching them (remember to switch back) Liberal but selective use of ether start spray to test for any vacuum leaks The runners are full open unless the gas suddenly developed high cholesterol - no rags, tampons ,dead rodents etc to be found. I'm hoping the problem is with the plug wires but no one locally sells them so if I have to replace them I have to make them up our wait for Mr Blunt to ship if I order them. If it's the dizzy I can get a rebuilt from IE but again that means delay in shipping to Canada. Will report. Edit: Valve lash fine Dizzy cap - no change with old so swap back to the new one Good spark all #1 and #2 wires swapped - no change No vacuum leaks found Still trying things - went to 45 140 (drop from 150) 185 and the lower rpm/cruise operation improved but still rough and lacks power at WOT

Plug wires? They produce spark when pulled and grounded to the block and the likelihood that they would cause such discrepancies in pairs? Valves were freshly set (by me so....) but I will check. But thanks

I had marked this as ANSWERED but have to take that back. Taking Toby's info and some searching the forum for comparable jetting given my engine (thanks for the info Bob), going one range hotter to NGK BPR5ES and adjusting my float level to spec I hoped I had resolved my set up. No luck. Assuming I can attach a photo you can see that plug 1 is sooty to the point of fouled, #2 is lean to the point of knocking #3 looks just about right and #4 is showing rich - and this is a new set of hotter plugs. Using Best Lean Idle setup procedure with 45 150 185 jets, it drives but not well and within minutes it's missing and jerking at any rpm but slightly above idle and #1 is fouled. Same thing happened when jetted 50 145 185. So everything is new with less than 500 miles on it and the timing set with ignition at idle (900rpm) 12 BTDC. Starts like a champ and the electric choke functions just fine. So what combination of air fuel and spark produces over rich on #1 and 4 and lean on #2 and 3 ?? One carb feeds all 4 sparks from a common source - fuel pressure regulator in place. Coil is newish Flamethrower and points replaced with Petronix. The same air/fuel mix is being supplied to each cylinder but with very different results so is the problem is electrical? Replaced the plugs had no effect. Replaced the dist cap with OEM had no effect. Checked for spark and all four showed strong spark. Distributor? Grrrrrr

Airflow. Thanks Toby - this helps - I was unsure whether there were three variables at work at idle/low/mid throttle or just idle and mains. I have a wideband meter in the car and that does help see what is going on. I'll focus on the idle and mains for start, low throttle and cruise and then main and air jets at WOT. Was 50/145/185 now currently 45/150/185.

Some questions and confirmations on what I think are basics for setting up a 38/38 weber. I have a stock motor and cam, Petronix, hotter coil and correct timing with less than 30,000miles since an unknown rebuild. The car drives between 2000' and 6000'. Personally, I think the carb is more than the engine needs given spec and altitude which makes getting it running well without be over rich at some point is difficult. What does a "hotter" range with respect to spark plugs have on ignition? The idle circuit controls mixture to 2000 rpm, the mains through the whole range and the air corrector can fine tune mixture above 4500rpm - correct? Does the air corrector jet have any effect at the lower rpm range? Say 2500 to 4000? Any comments on the questions appreciated.

Mlytle, I did variations of "rear coilover" and never thought to include "towers" so thanks for that. It's always asking the right question that gets the right response. I'll continue the search but the green one from moespeed looks very familiar and did add 1.5" to the height as suggested by Creede.

Thanks Creed, hadn't thought about the height of the towers and length of travel - good point. I recall seeing another installation using heavier gauge wall thickness pipe and replacing the OEM towers. Also thought of doubling up the sheet metal of the wheel arch with a 2" skirt around the tower using plug welds. Trying to avoid a roll bar connection. Doug

I'm looking for examples/how to do's of rear coilover conversions - particularly the reinforcement of the to end shock mount "towers". I'm slowly going through the Project blog pages - all 34 times 20 of them so any assistance would be appreciated. Doug

Just assuming - two very rich and two lean but I get what you are saying - should all be the same. Feed by same single weber carb so probably not carb/fuel related. Checked multiple times by three different people that the leads are correct to and from distributor to plugs for firing sequence 1-3-4-2. Valves all set at .007 cold. Good spark (grounded to block while cranking to test) with new plugs. Swapped in another distributor to test and no change. Assume since the cam wasn't TDC when the crank pulley and flywheel were that it must have to do with the engine timing not ignition timing. Still have to resolve the timing chain issue before I can do anything else.

No, the valve train is fine so maaaybe 3 teeth but definitely out by 10 - 12 degrees. When the engine was running cylinders 1 and 4 were back and sooty and 2 and 3 were tan to white/grey. I assume that means the plugs on 1 and 4 were firing after TDC and 2 and 3 before. The plug to 3 was defective so replaced with new set and then did the TDC reset which gets me back to the problem at hand. But it ran with out the sound of metal to metal contact. I'll pull the tension plug and let the chain sag, reach down into the bottom with some coat hanger (special BMW tool...) and try to see if I can lift/fish the chain off the crank sprocket and pull up the slack - assuming there is some slack. Doug

Where to start? Turns out the crank cam sprocket was rotated 4 teeth from TDC relative to the crank pulley TDC and the flywheel timing mark TDC. In an effort to get this thing to run better I removed the cam sprocket, lifted the chain and rotated the cam to get the TDC mark to line up with the oil spray bar. This was done with the chain wired in place to prevent it from slipping off the crankshaft double sprocket - or so I thought. Now all TDC marks are in agreement. Put everything back together, put the plugs in and leads on then turned the key. There was/is a clack, clack, clack sound from the front of the engine that I'm pretty sure is from something hitting the lower timing chain cover. The other symptom is the engine has a point about 10-15 degrees either side of TDC where turning the engine with a socket on the pulley nut where rotation becomes blocked until you really reef on the ratchet bar and then it turns freely. Happens in either direction. Happens every time you go back across TDC even after you rotate through 360 - something binds at the same point but not enough to lock it up. In looking at the Haynes digram of the timing sprockets, chain and guides I'm guessing that in putting this back together I have allowed the chain on the guide side to drop off the double sprocket one or two links. Then when the tension goes back on the chain when the tension plug pushes the chain to the centreline the chain engages the sprocket with a small loop hanging down. Because the upper and lower sprocket are two fixed rotating points the chain tensioner cannot take up the slack and the loop flops around hitting the case. So a couple of questions other than "has anyone else done this"? Can the loop be somehow flipped over a tooth or two - you're doing this blind from above reaching down into the lower timing case - and how best to do this? or Can this only be resolved by removing the lower timing cover and everything associated with that (rad, alt, water pump, crank pulley etc)? Forecast is 3" of rain mixed with snow over the next three days so this is as good a time as any to do this. I just pray this is really the problem. Any advice appreciated, Doug ?

Just ordered mine. Looking forward to seeing myself.

Still have to figure out why the 1+4 are rich and 2+3 are lean. With only one carb into a common manifold it isn't the carb/fuel system. My worst nightmare would be the timing chain skipped a tooth left or right which might explain this issue. Can't remember how many teeth are on the cam sprocket but one tooth could be 10 - 15 degrees which is huge. But thanks again.

Through switching plug leads and plugs around I confirmed that plug #3 is pooched, bought a new set of NKG (since they didn't have Bosch WR7DC) and did the pull the lead on each cylinder with the engine running to test. The engine runs much better (still a little rough) and I can continue setting up the carb when my main fuel jets arrive via post. Thanks all and Peterschop in particular.

Will check the plug as well. Thanks.

How do you check if the Petronix pickup is not the problem? If the Petronix works on cylinders 1, 2 and 4 can it fail on cylinder 3?

Peterschop - I had a spare cap and tried it with no luck. I'll try your suggestion and get back to you.

Thanks, I have checked for vacuum leaks at the carb. No spark on cyl 3 points to the distributor as most likely problem. Petronix? Probably not coil since it sparks 1,2 and 4 just fine. Hope it's no the distributor itself but agin works on 1,2 and 4 so....

Winter finally gave up and the car is back on the road but running poorly - was fine last fall when took it off the road. Stock engine with 15,000mi since rebuild with 38/38 webber that starts instantly and idles well at 800rpm - slight stumble. Timing set to factory numbers. Symptoms are missing/rough running as rpm increases and air fuel ratio becoming very lean under throttle. Plugs 1 and 4 black and sooty, plug 2 very lean and 3 light tan with sooty base. Checked valve at .007 throughout, plug leads from new dist cap to correct plugs, Petronix wired correctly and everything involved is new within the last 3 years and very low mileage. No pitting or carbon on the rotor or distrib cap. Carb settings unchanged since last fall and set using wideband A/F meter. Checked vacuum advance by sucking and blowing on the hose with the engine running which may be crude (and rude) but should an effect on the engine operation. With the engine running I pulled each plug lead off the plug and the engine stumbles on cylinders 1,2 and 4. Pulling lead 3 had no effect on how the engine ran so thought I had found the problem. Replaced plug lead on 3 but that had no effect so it seems there is no spark to cylinder 3 and it is upstream from the plug lead. So before I start replacing parts - culprits would be coil? dizzy wobble? Comments? Doug

Can't hurt then - thanks.