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Old 06-11-2019, 08:51 AM   #1
bmos
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Location: Cumberland, ME
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I haven’t had a build thread since my first car… this wasn’t supposed to turn into a build but project cars are an addiction!



Mods:
Performance:
Innovate Motorsports SCG-1 Solenoid Controller (13psi over ambient)
DeatschWerks 300C Fuel Pump with Low-resistance Wiring Harness
Turbosmart Kompact 25 mm Dual Port (Atmospheric)
Magnaflow High-flow Catalytic Converter
IPD Turbo Camshaft
Polyurethane Strut Rod Bushings
IPD Adjustable Polyurethane Panhard Bar
Firestone Firehawk Indy 500 Tires on Straightened and Refinished Hydras
Cosmetics:
Repainted in BMW Pyrite Brown Metallic
Powdercoating
Rally Armor Mudflaps
Painted Exhaust Tip
Deeworks 8V Vacuum Line Bracket

Last edited by bmos; 06-16-2019 at 06:50 AM..
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Old 06-11-2019, 09:05 AM   #2
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Please excuse this poorly-organized post, I don't have a lot of photos of most of what I have done. I just reference the chronological receipts binder when I want to see when I did something/what I did.

I bought this 1991 740 Turbo estate in 2016 but the story goes back a couple years earlier when a friend was looking for a new car. I saw this on Craigslist and sent it to him, not expecting it to stick but he was immediately interested since he grew up in old Volvos. I found out it was a California car that had been driven to Rhode Island around 2012. Someone in its history had clearly been into it as there were some IPD parts, lots of painted suspension/underbody parts, and Bilstein HDs. The big stack of receipts was what really sealed the deal and I told my friend to buy it but to be prepared for the various issues it had.

He paid me to detail the car and do some cheap fixes while he was away for a few months (spark plugs, fix taillights, hatch supports, etc) and drove it for a couple years with minimal investment.

His ownership was mostly neglectful and I witnessed many an oil pressure light corning with low engine oil and by the time I bought it off him for $600 it had quite a few problems but given how clean the body was, I leapt in.

The first order of business was fixing the suspension. Every bushing in the front end had massive amounts of play except for the ipd poly strut arm bushings. I replaced them all and repainted the arms the same Swedish livery that the previous owner had over a decade before, and replaced the strut inserts with Sachs. The front left had failed so spectacularly that the strut came off the car in two pieces without a spring compressor required! The front left was spared the issue of wearing out since the upper strut mount was missing the upper washer bushing (this was hard to find since it’s NLA but I got a parts car)! While working on the suspension I also replaced the crankcase ventilation system, intake gaskets, throttlebody (the throttle plate was loose due to stripped screws and was occasionally sticking open in the bore). The brakes were also in terrible shape, bad master, and mostly seized so occasionally you’d get some runaway acceleration issues… Sketchy stuff. I had to have the cluster repaired to get the speedo+signal for the LH2.4 and to fix the fuel gauge.
91 740T Front Suspension


After getting the front end sorted out, I began servicing the driveline. When I pulled the rear diff cover I was amazed to find that my open-diff car actually had a broken locking diff. The filter was totally full of metal shavings and a few chunks so I removed it from the diff cover and cleaned the diff out as best I could. After months of waiting, the repair parts arrived from Sweden and I had a locking diff again. I’m sure the wear on the rest of the surfaces is pretty bad but at the time I was just wanting to get the locker working so I could get through the winter without getting stuck too often and a full rebuild was not in the budget. It’s been working great ever since!


When I got it back from the diff shop I started to focus on the engine drivability. It was running way rich and would actually stain buildings it was backed up to at cold start (you should see my garage door). After finding an LH2.4 breakout box I followed through the greenbook diagnostic steps and ended up finding a bad ECU and a number of out-of-spec sensors. At this point it was running really well but with an occasional light miss at idle and without any more codes. I also changed out the timing belt and all front engine seals, thermostat, water pump, belts, etc around this time. Now that the AFRs were more reasonable under boost, I began the inevitable slide towards turbo performance. I got an electronic boost controller (it’s nice to be able to play with in the cabin but I think I should have got the GFB instead of this Innovate unit) and have been running 11psi ever since. Eventually I started noticing a hesitation when the fuel was low and replaced the two pumps with a single in-tank DeatschWerks 300C. Full disclosure, I broke the sending unit when I was there and haven’t fixed it yet because pulling the tank without a lift is pretty rough with all the oily undercoating on it. I also installed the wasted spark conversion board and found a pretty clean mounting strategy about where the distributor used to be. I also converted the stock early-style 13C to run a Turbosmart BOV with a custom-machined CBV adapter with dual o-ring grooves to reduce the vacuum leak present at the stock unit’s outer triangular flange.
91 740T Fuel and Spark


Installed a set of RallyArmor UR+ mud flaps for that rally-esque look and a lot less crap on the car when driven in the rain+snow.
91 740T Rally Armor UR+


After sorting out the fuel issues, the exhaust was next on my list. The manifold was ticking so I pulled it off for an inspection. Found a missing (snapped) bolt and broke another taking it out. The manifold was also cracked but I couldn't see any light through it so I called it good and haven't heard any telltale ticking. Bought a 90degree drill and got the studs out and no more ticking. Replaced the oil filter relocation bracket o-ring, turbo oil drain o-ring and gasket, and installed a new IPD turbo cam with new valve hushers, re-shimmed, and had my valve cover powder-coated. I also installed a stock-style Starla exhaust that quieted things down nicely compared to the IPD/TME exhaust (which had a lot of off-throttle drone under 3k rpm) but definitely reduced the power a little bit. If/when I go big-turbo+CD009 I will have to re-evaluate this and figure out how to keep it fairly quiet (j-pipe might be the route to take) but for now I’m happy. Before selling off the IPD exhaust I polished the tip and WOW did it look nice on Craigslist. I also installed new torque arm bushings at this time and have a set of poly trailing arm bushings and clamshell bushings to install.
91 740T Rear Suspension and Exhaust


Built an aux-jack adapter harness for the stock radio/graphic EQ that keeps the EQ functional (even with a phone connected) and just interrupts the signal from the radio when a cord is plugged in. Thanks so much to cleanflametrap for making this possible with the great writeup on brickboard which I was able to adapt to incorporate the EQ. I have Rockford Fosgate speakers in all 6 stock locations and it sounds quite nice to my ears with the factory amp, eq, and radio.

I got the driveshaft re-balanced, a new rear u-joint installed, and an OEM center bearing installed. Even with the driveshaft off the car the old joint didn’t seem to have play but on the balancer it was pretty rough. Now the car is almost perfectly smooth on the road other than the inescapable engine vibrations of a non-balance-shaft 4cyl and rough wheel bearing (new OEM unit should arrive in the mail today!). I have also drained/filled the transmission once and plan to follow it up a couple more times as the Blackstone Oil Analysis showed levels of copper literally off the charts. Then after 10k miles I'll be able to discern the true rate of wear. The transmission shifts great although turning on/off overdrive is a bit harsh. While I had the pan off, I had it powdercoated to inhibit future corrosion as it was starting to surface rust slightly.

The biggest thing I’ve done is to have the car repainted. This took place right after the wasted spark conversion and was done in BMW’s Pyrite Brown Metallic. It’s about a 7/10 job with a couple runs, sanding marks, etc. I have to take it back for some rework but I love the color and it really makes the car IMO.
91 740T Paint - Pyrite Brown Metallic

Last edited by bmos; 08-13-2019 at 08:24 AM..
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Old 06-11-2019, 09:23 AM   #3
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I've pulled the head off of my parts car and will be getting larger valves later this year. I may build a stock block 1st oversize due to the low-oil-pressure past of my current engine.
91 740T cylinder head and airbox update 1


I am also in the process of prototyping a replacement air filter enclosure.
Here's a live window into the progress of that:
https://a360.co/2R95OaH

One weird story I forgot to mention was the sunroof that was silicone-sealed. I scraped the silicone out and found a working sunroof. No plugged drains or leaks, just slightly misadjusted. It works flawlessly now.

Last edited by bmos; 06-13-2019 at 04:48 PM..
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Old 06-18-2019, 11:09 AM   #4
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I finally got the A/C system evacuated and charged after installing the NOS r134a conversion. It's so nice to have ice cold A/C in a car with so many windows.
I wonder how much this will tank the already mediocre MPGs... :| I'm back to my usual 19-20MPG now that I've fixed the lean condition from the failed in-tank pump (the economy had gotten to 27! dangerous territory for a redblock, I'd assume) although I definitely should get my wideband sensor installed soon...
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Old 08-13-2019, 08:19 AM   #5
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AC made no difference to fuel economy, thankfully, but was lovely until the compressor leaked out its charge.

Poly trailing arm and clamshell bushings installed yesterday, way easier than most suspension work I'm used to. It's a little less compliant feeling in back now but way more composed. The rear pretty much stays behind the front over railroad crossings now (it used to spear right a little).
91 740 Rear Suspension Work


Couple days later the TRW steering rack went in. Bought a Maval rack about 6 months ago which started failing right out of the gate but FCP Euro stopped carrying the Maval 740 rack so they sent me a TRW rack instead (way more expensive and nicely-built -- the Maval rack didn't even have a pinion seal!). This has mostly cured the steering wobble I have at about 37mph (and again around 75 on the highway) although some still remains that I haven't tracked down yet. I also drained and flushed the ATF from my steering system in favor of CHF 7.1 as per an old TSB for steering noise complaints.

Next up, the tailshaft bushing that started getting pretty rough coming home from the New England Forest Rally last month.

Last edited by bmos; 08-26-2019 at 07:03 AM..
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