alternativez2003

Spent the past weekend pulling everything out of the 635. I feel a little bad about basically trashing such a nice car, but it was getting some age (rust) on it. I have other cars to maintain and restore, and I'm 5 years into my home remodelling/rebuilding (large) project with at least a couple more years to go, so g'bye 6er. Told my extremely supportive wife I've either made a huge mistake or everything will work out just fine, and I lean very hard toward the latter prospect. The Z is so much more fun to drive anyway, and to me, worth more and more unique than the 6, and I've been sitting on this 70 Z for over 15 years. Bits from the six will go to another 6er owner, to the Z and to my 76 2002, so it is not a total waste. Next steps, dry fit the engine with trans, diff, etc into the Z, figure out mounts, driveshaft, transitions between and within systems, and location of auxilary stuff, then fabrication, pull engine for rebuild, body work and paint, well, you guys know the seemingly never-ending process...wish I had all the time and money to push it, but so much to do with work and other projects, it will take a while, but it's exciting to me to make this progress and to get one more vehicle out of my driveway and off the insurance. Later, Jim

Searched the thread and just wondered if any others had completed their ps conversions. I couldn't get the site of photos someone had posted. Any updates would be appreciated. Thanks. Jim

the sumps on the 3.5 L6 vary between series, but the pre 89 or so has the sump a few inches back from the front of the pan, so my 85 3.5 drops in nicely just behind the cross member and below the steering knuckle. Later sumps are at the front of the engine and I'm not sure they will work. I may have some difficulty adaptin AC and PS if I use it, but I'm sure it can be done. I'm certainly not the expert, but the sump is a concern. Also, IMO the earlier electronics are satisfactory even though the later models may have had more hp, but the OBD II would be more complex to mess with. After getting mine assembled I plan to explore megasquirt as an upgrade. Later, Jim

I'm going to tear apart the 85 635 very soon. I've been parting it out some. It's the only reasonable choice for me right now, since I already have the car. I think at my age I will be satisfied with the near 200 hp I can put into the Z, and if not, there is the turbo route. I really want smoothness and a clean, well-appointed, reliable Z, so the power is only one issue. These engines are strong, durable, and simple to work on, and actually parts are very accessible and not as expensive as one might think. If the six can pull the overweight 6er around, I think it will do fine with the lighter Z.

My, does time fly? I was just checking in and saw your post. The M engine would be fantastic. I haven't done the 3.5 swap, because I was driving the 635, and hated to give it up. It's a great car, but beginning to age. Now I've taken it off the insurance and it's parked waiting until school lets out (I'm a teacher) so I can actually start taking it apart. The problem of the M engine may be the fit, but for me it's the cost. Plus, if you want to turbo, the M would not be such an advantage. The lower comp 3.5 (8:1) would be a better candidate, and cheaper too. Besides, it's pretty good power as it is. Hope you check in, and let me know how it's going. alternativez2003@yahoo.com Later, Jim

Well, I haven't made any progress on the 3.5 into the Z as I am still remodeling my house. There is only so much you can do (or afford) at a time. Actually, my 635 has ben down with a very curious "no start" problem. Believe me, I've one through everything, and I don't know what is is yet, ad don't have a lot of time to mess with it right now. It could be any combination of things. The good thing is, I've studied and learned a lot about the electronics and identified a lot of electrical system concepts to transfer to the Z. The thing is, I haven't been able to find out if anyone has ever come up with a different intake that comes in from the driver's side rather than the not so attractive over the cam cover original intake of the 3.5. I would like to use an available maf system from the left side to better fit under the hood and to be more efficient than the oe air flow meter. Also, I would like to consider bore/stroke options to increase from a 3.5 to a 4.0 liter engine, partly for the increased hp, but partly for the idea of a true 2-4-0 designation like bmw might use. I'm silly there I know, but the car should be able to hang with "real" bimmers when I get done with it. Since it is a 1970, I would keep the C pillar 240 emblem, but paint the bmw blue and white roundel inside the emblem. Only a few people would recognize the concept, Datsun outside, bmw inside, the best of both worlds, so to speak. Well anyway, obviously I had a little time to kill, but I just thought I would check in and see if anyone is still on this thread. Later, Jim

I had the same problem with my 85 735 BMW. Obviously a heavier car, but it occurred on the front suspension in extremely cold weather. You could consider stiff bushings, but more likely it's springs or shocks. If the springs, which actually support of the weight of the car, have lost their tensile strength, the spring will not push the car back up after compression. Likewise, if, as has been mentioned, the shock, which is only meant to dampen the compression and rebound, has ceased to function, by binding basically, then the spring cannot push the car back up. In either case, invest in a new set of springs and shocks; you'll appreciate the new ride, and it should cure the problem. While you are at it replace any suspension bushings, and your car will ride and handle better than new. Buy a pair of spring compressors, or borrow a pair from a friend. It's not a difficult job if you are mechanically inclined, but be careful not to launch a spring through the fender. Just remember which are front springs and rear springs. Good luck, Jim

I had the same problem with my 85 735 BMW. Obviously a heavier car, but it occurred on the front suspension in extremely cold weather. You could consider stiff bushings, but more likely it's springs or shocks. If the springs, which actually support of the weight of the car, have lost their tensile strength, the spring will not push the car back up after compression. Likewise, if, as has been mentioned, the shock, which is only meant to dampen the compression and rebound, has ceased to function, by binding basically, then the spring cannot push the car back up. In either case, invest in a new set of springs and shocks; you'll appreciate the new ride, and it should cure the problem. While you are at it replace any suspension bushings, and your car will ride and handle better than new. Buy a pair of spring compressors, or borrow a pair from a friend. It's not a difficult job if you are mechanically inclined, but be careful not to launch a spring through the fender. Just remember which are front springs and rear springs. Good luck, Jim

Hey, I must be nuts reading all these posts because I have better things to do to, but I was really surprised that you guys would consider being elitists about any hybridization of a Zcar; that's what Zcars do best! I'm working on a BMW 3.5 L6 into a 70 Z and there is nowhere that I can see ideas as I have here, even though there has been little on this site specifically for that concept. I did a 327 into a 70 back in 1973, so V8Z's have been around since the Scarabs of the 70's, but I didn't realize, I guess, that this site was intended to be so righteous about them while claiming no "Nissan only" creeds by others. Sorry if I've offended, but my only posts here were researched and mostly intended to seek out others with a similar interest. I log in nearly every day and cruise new posts and old, and thoroughly enjoy the quality of the site. I can show my wife posts here without worrying about unexpectedly finding naked girls instead of centerfold quality pictorals of Zcars. I'm also an English teacher and boy, could I use some posts for editing practice, so I appreciate the desire for professionalism. Yes, there are other sites, but you folks have done a superior job here, and by doing so, you will grow and attract a greater following. Sorry you've had to deal with difficulties, but honestly, some of the language and tone by some of the administrators' posts is setting a poor example for these "newbies" you refer to. You were once novices or newbies, and someone probably helped you, and now you have crossed over to the experienced side and have lots of experience and the contacts to help the next generation of hot rodders. Be glad you've had the opportunity to help somebody else. Good luck

Many exhaust are centered: Mini S, old 2002 BMW's, etc. Just look at how they did it. Check out the early Pete Brock BRE Z racers. Of course the racers had fuel cells, but the exhaust in the center can look cool, and it seems more efficiect in terms of flow. I like that the straight system would be less cluttered than the 240 system's sharp bends to get around the gas tank. I am putting my 85 635 BMW engine et al into my 1970Z and intend to run the exhaust straight out the center just as it does on the 635. I haven't determined the method, but I may cut into my Z tank, or use the 635 tank in some way. I have considered removing the spare tire tub if necessary. I plan to use run-flat tires anyway... A possible problem is fitting enough exhaust components into the shorter length. It just means there is very little tubing between cat, mufflers, and resonators. I intend to keep my Z a little quieter than the 635 is stock. It has a very solid big six rumble which is nice, but can be too much for not-so-affected passengers on longer drives. Just have to turn up the tunes, I guess. Another possible drawback is having the hot tailpipes and exhaust exiting at the center; if you are loading the rear with the engine running, you have the exhaust in your face, or at least at your legs. Consider if that will be a concern for you and anyone else using your car: hot summer day, shut off the car and go stand at the rear to unload the picnic... Also, keep in mind the the turbulence at the rear and the worry of exhaust fumes entering the cabin. On a 327 Z I did many years ago, a body shop friend did a nifty little surround over the top of my exhaust tips which helped the appearance as they exited the rear valance in the stock position. Many cars now do such a design touch, and it really looks nice, and it may help the air flow around the tips to help disperse the fumes. As far as looks, I would again look at how other cars have taken car of the design. Good luck, Jim

Thanks for the response. I notice you are in Ontario. I've been communicating with Charlie Osborne of Zedd Findings and a guy named Rick at Bradford Nissan about some parts. I know Ontario is a large area, but I just thought it was interesting. Sorry about that rear lower section in the picture; is that your car? I feel lucky, my 70 is in extremely good condition, but then it's been in my garage for about 15 years, totally stripped down. Actually the only time behind the wheel was towing it when we moved it a couple of times. Sad, I know, but I have so many DIY projects, it has been waiting. I am really getting anxious now, as I turned 50 last August, and I want to get it going soon. As a matter of fact, my daughter is planning to give me her 325 that I gave her a few years ago as soon as she and her husband take delivery of their new Mini S, so I am hot to take my 635 apart. It may sound odd to dismantle a decent car; a 635 is a nice auto, but as you noted, lots of little things get costly, and if I am spending money on a car, I want the Z and I really enjoy the 635, so I think they will make a great hybrid. Let me know if you get any great ideas. I check the forum when at work if I have a chance. We are in central Indiana, about 30 mi north of Indianapolis. Later Jim

respond here also. Yes, there are excellent years; it depends on the car you are swapping into. The post 3.5 L from post 89 models have a different oil pan which would make the installation more difficult, so I'm using my 85 635 as a donor. I love that car but the power steering/brake booster system has been high maint. and the car is just beginning to wear out cosmetically, and I loved my Z when I was 19; I have had a 1970 stripped in my garage for 15 years just waiting for the right combination. There is also a direct design connection with BMW and the Z (but don't tell any truly chauvinistic Datsun people). The stock 3.5 offered 180 or so hp, and intake improvements and a chip should make a reliable 200+ according to the Dinan site. So either look for the smaller, lighter 2.5 and 2.8 in the 3 series, or the 3.5 in the 5, 6 and 7 series. The 535i from the 85-89 era would be an excellent place to start. Many had 5 speeds as does my 6. I would probably install a Quaife diff for better traction in the Z, but otherwise the 635 drivetrain would be more than adequate to propel a Z nicely. Of course an M engine would be supreme, but very costly I think, if you look at the prices of comparable parts in any catalog such as BMP. Also, on these forums, lots of people seem to be dreaming of incredible horsepower in a smooth, daily driver, and I suppose it is going to stay on the road in the rain. I think a near stock BMW without internal modifications will offer strong, reliable performance without having to spend weekends tuning and tweaking. If you want to drive it, it has to be dependable. You can have huge fun in the garage building it, but the real fun is in driving. If I want to work on something every other month, I have a 1976 2002 which I drive to work everyday and share with my 17 year old son. We both love it. Who knows, one of these days I'll put the 2.5 from my 87 325e into it, and then a 325i head and fuel computer...Will it ever end? jimfsnyder@hotmail.com and alternativez2003@yahoo.com

As a matter of fact, at least in my mind, some of the strongest most reliable engines, and they are very easy to work on. I've had some postings on the HybridZ forum under the other engine category, but got only a few responses. I have owned several mid '80's and my 85 635 Csi will soon become the donor of its entire drivetrain and electronics to my 1970 240Z. I lowered the 3.5 from my 86 735 into the Datsun and the fit was very nice. In particular, the pan fit so well behind the crossmember and below the steering knuckle of the rack, I was amazed. The rearward placement distributes the weight better, it would seem, than the original six, so additional weight would not be such a concern. An M engine would obviously be an excellent choice, but I have the 635 and know it well, and it flies, so I'm sure I will be pleased with this power in the lightweight Z. I am interested in refining the intake of the NA 3.5, replacing the huge, boxy crossover intake with something smoother from the left side. That would clear the top of the engine of a lot of clutter and actually lower the center of gravity of the tall engine somewhat. It would also more resemble the configuration of the 2.4 with a crossflow head. I just think this would be an improvement in the effiency of the intake and therefore improve power even if only slightly, while improving looks greatly. I haven't found any intake options for the regular 3.5L, so if you know of anything, please let me know. Thanks, Jim jimfsnyder@hotmail.com alternativez2003@yahoo.com and in this forum

There seems to be some interest in swapping a BMW 3.5 L straight six into the early Z. Let's keep the communication going. I will do this swap, but it takes time and planning. My '85 635 csi 5 spd will be the donor. I am also interested in converting to a mass air flow meter and upgrade with a Dinan or Conforti chip, and would like to create a new intake from the driver's side. The BMW piece comes over the top of the cam cover from the right side, and it's ugly. Besides, there is some preference to imitate the original Z configuration, making it look cool and ideally even making it flow better. I want to know what other ideas anyone would have, and if anyone has ideas for more hp from the older BMWs while maintaining reliable street driving characteristics. My emails are jimfsnyder@hotmail.com and alternativez2003@yahoo.com if we want to avoid frustrating the good folks at the HybridZ forum.

The oil pan has a flat front which aligns perfectly over the crossmember, athe angled drop in the pan slipped perfectly behind the steering knuckle and the engine seems to come in farther back than the L series, so the weight would be slightly farther back into the mid-section of the car. When I tried the 735 engine I didn't have the trans on it, but the 635 is a 5-spd manual. I haven't done the actual measurements, but it seems like a very comfortable length for the driver. I don't think the weight could be more than the sb V8 I did many years ago. It looks very "do-able," actually it's just waiting to happen. I would use the diff and wheel size of the BMW drivetrain to keep the speedo as close as possible, and have the advantage to the taller wheels/tire setup.

I'm not sure why you would want to rotate the injectors. Which injectors do you mean? What would you do with the wire leads? Injectors spray a conical mist anyway, so what would be gained? Who knows, there have been stranger ideas that have given hp gains. Amazing what you can come up with a 3:00 a.m. Jim

Hello, I'm new to this forum. I sent the message to Boobala, but I'm interested in thoughts on the 3.5 L straight six, trans, diff, etc. from my 85 635 Csi swapped into my 1970 240Z. I did lower the 3.5 from my 735 into the bare Z and it seems a fine fit. I did a nice 350 bhp 327 swap back in 1973, but missed the character of the six. Any ideas? Jim

Boobala, you mentioned some time ago a question of swapping a BMW straight 6 (3.5) engine into a Z. I am serious about that very thing; my 1985 635 Csi is the donor. Did you ever get any response? I did the SB 327 swap many years ago, but I much prefer the six and the 635 has always reminded me of driving the 240. Do you know the whole Albrecht Goertz story? Jim 1970 240Z