To rebuild now or later

[joebarthlow]

first read this...

 

https://www.amazon.com/Ran-When-Parked-Resurrected-Road-Tripped/dp/099895070X?SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-osx-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=099895070X

[TobyB]

Quote

 ALL manufactures have a redline that is set far below what the engine can take.

BMW, however, set the M10's redline at about 300 below where the rockers fail when the valves float.

6800 (ish) is about all the stock springs can handle, if you wind it out to that and hold it.

At 7000, the intake rockers start to give it up.

 

Agreed, though- from the 318ti to the 330ci, BMW engines make great power in the 4500- 6500 range.

 

No, OP, just drive it.  As everyone else has already said, futz with everything else first, including

getting the carb and ignition up to snuff.  

 

t

 

[RogerRamJet77]

I believe there are a couple of changes BMW made with the 1976 model that make it unique among 2002s to get the performance comparable to its predecessors despite the addition of performance robbing emissions controls.  A E12 head with larger intake and exhaust valves, a smaller diameter flywheel (215mm instead of 228mm), and 3.90 final drive ratio in the differential.  Earlier 2002s had a 3.64 final drive ratio.  At 75 mph, the engine will be turning ~4200 rpm with a 3.90 final drive and ~3900 with a 3.64 final drive (see attached).

2002 gearing.xls.xlsx

Edited December 12, 2018 by rockyford77

[Conserv]

10 hours ago, rockyford77 said:

I believe there are a couple of changes BMW made with the 1976 model that make it unique among 2002s to get the performance comparable to its predecessors despite the addition of performance robbing emissions controls.  A E12 head with larger intake and exhaust valves, a smaller diameter flywheel (215mm instead of 228mm), and 3.90 final drive ratio in the differential.  Earlier 2002s had a 3.64 final drive ratio.  At 75 mph, the engine will be turning ~4200 rpm with a 3.90 final drive and ~3900 with a 3.64 final drive (see attached).

2002 gearing.xls.xlsx

 

A slight clarification on the above:

 

The 49-state version of the U.S. 1976 model used the E21 head, shared with the then-new e21 series — I’m fairly confident the the name of the E21 head, introduced in the spring of 1975 on the new e21 series cars, is not a coincidence. These 49-state versions, of course, were the only ‘02’s to receive the 3.90 differentials: California versions of the U.S. 1976 model used the E12 head, and the more common 3.64 differential.

 

After 40+ years with my ‘76’s 3.90 gearing, when I recently swapped in an LSD, I chose a 3.64 unit. That wasn’t an accident. The former gearing may have well-suited my 20’s, but the latter better suits my 60’s....?

 

Below, cruising south through Fancy Gap, VA in my ‘76 last August. The indicated 72 mph was very close to the actual speed according to my GPS. Given that the car already had the 3.64 LSD at the time, I’d guess that my tach has some error, and the rpm’s were closer to 3,750 than to the indicated 4,000 (stock 165HR13 Michelin XAS tires).

 

Regards,

 

Steve

 

Edited December 12, 2018 by Conserv

[Conserv]

17 hours ago, AJ2002 said:

 I get frightened something will fall out the thing at 4k revs. ?

 

And, if that happens, I’d take it as a sign that the “performance M10” is meant to happen now! ?

 

Regards,

 

Steve

 

[wegweiser]

As others have stated, see what kind of oil consumption it has, after a few hundred / thousand spirited miles. I never drive mine below 3200 rpm, ever. 

 

After a rebuild with fully functioning rings, I've switched from 20/50 to 15/40 after seeing some remarkably sky high oil pressure readings on moderately cold starts. 20/50 is fine for cars that consume oil, but on a fresh motor, I feel like it's overkill / too thick. Thinner oil seems to dissipate heat better, too. YMMV. 

 

 

10-11 hours at a time. 4 speed. 3.64:1 rear end. From East coast to West coast and back. They love this. It's what makes these engines so damned great. The key is obsessive maintenance and mindful respect for the equipment. 

 

Start with the basics. ignition timing, carb tuning, valve adjustment… then throw parts at it as needed. Enjoy it.

 

Note: Unlike other motors you're perhaps familiar with, NEVER allow an M10 to overheat. EVER. At ALL. Warped / cracked cylinder heads are the result. You may find that the cooling system needs some help, after you get some miles on it. Be prepared for that possibility and keep an eagle eye on the temp gauge. 

[Henning]

5 hours ago, Conserv said:

Hmm, Steve.

Wiki tells me that there's a speed limit of 45mph instead of 75 on the blue ridge parkway. Please jump into the article and refresh.

The engine of your 76 still needs some training after overhaul I guess? 81 miles at that level of gas indicator seems to me some...  Ah, I understand. You didn't fill up completely to avoid gas spots around the filler cap. Good.

And I'm happy you don't smoke!

Yours,

Henning

 

[Simeon]

1 hour ago, wegweiser said:

10-11 hours at a time. 4 speed. 3.64:1 rear end. From East coast to West coast and back. They love this. It's what makes these engines so damned great. The key is obsessive maintenance and mindful respect for the equipment. 

 

This is the best advice. The M10 and the 02 was designed to be run hard on the Autobahn. I love driving mine on long trips too - cruising at 70mph (speed limits are all in km/h here! ?) in 4th gear and then dropping the throttle to feel that mid range acceleration to overtake something.  It still isn’t the fastest car around but it just feels... right.

 

It takes a lot of work (and money) but eventually you get the car as reliable as a new car and work consists of staying on top of maintenance. Like Paul, I would not hesitate to set off for a 12 hour drive and then do it again the day after. The only limitation is probably my back putting up with the seat. 

[Stevenc22]

Yeah surprisingly my tired old M10 had no problems running 4000rpms all the way to Mid America in Arkansas. These engines really are solid. They start to smoke and burn some oil but pretty happy running forever.

[Conserv]

3 minutes ago, Henning said:

The engine of your 76 still needs some training after overhaul I guess? 81 miles at that level of gas indicator seems to me some...  Ah, I understand. You didn't fill up completely to avoid gas spots around the filler cap. Good.

And I'm happy you don't smoke!

Yours,

Henning

 

 

I’m glad you’re paying attention, Hen! ☺️

 

I guess I need to manage your expectations! Don’t expect to get more than 23 mpg out of my ‘76. Its fuel mileage range, from Day One, has been 17-23 mpg. The balanced and blueprinted engine, and the shift from 3.90 to 3.64 differential, haven’t changed the fuel mileage one iota — I suspect I rev it even more since the rebuild! As it happens, it was 93-94 degrees F when I took the photo and the A/C was on continuously. I hope you don’t mind. Covered 600 miles that day!

 

Best regards,

 

Steve

 

[AJ2002]

Wow, thanks for the tutorial on de-smogging.  I honestly don't know what's left of the smog system and what is not.  Maybe I should post a few pics.  But the idea of relieving the engine of burdensome equipment is a good one.  In fact, that reminds me that the engine has a AC compressor system (after market probably).  The car had a long life in New Mexico - hot! It does not work (has not for a couple years the previous owner said) but is adding weight and absorbing some torque I suppose...and there isn't torque to spare.  Need to remove that also.  I don't plan to run AC, but I may keep the system just in case the NC heat beats me down one of these summers.

 

Thanks also for the thoughts on getting a shorty header.  I was wondering about this.  I looked on IE and they are out of stock.  But there is also a shorty header offered by Top Speed.  Might look into that. Otherwise, I was planning to take the manifold to a master welder I know and get the crack welded for now.  I need to read up more on the de-smogging tricks.

  

Edited December 12, 2018 by AJ2002

[Conserv]

23 minutes ago, Simeon said:

 

... I love driving mine on long trips too - cruising at 70mph (speed limits are all in km/h here! ?) in 4th gear and then dropping the throttle to feel that mid range acceleration to overtake something.  It still isn’t the fastest car around but it just feels... right.....

 

 

+1

 

Yes, that’s precisely it! When you’re cruising at 70 mph, near 4,000 rpm’s (with a stock camshaft), the engine is so....”on cam” and responds instantaneously with a healthy surge to additional accelerator pedal: no shifting, just more pedal. And that surge is wonderful from 4,000 to just past 5,500 rpm’s (remember, stock camshaft and original Solex!).

 

Best regards,

 

Steve

 

Edited December 12, 2018 by Conserv

[Conserv]

18 minutes ago, AJ2002 said:

wrong thread.

  

 

Sorry to wander off topic, AJ! I’d swear that never happened before...?

 

Our German colleague, Henning, is hoping to inherit my one-owner ‘76, and, thus, keeps close tabs on my use and modification of the car.... ?

 

Regards,

 

Steve

 

Edited December 12, 2018 by Conserv

[Conserv]

1 hour ago, AJ2002 said:

Wow, thanks for the tutorial on de-smogging.  I honestly don't know what's left of the smog system and what is not.  Maybe I should post a few pics.  But the idea of relieving the engine of burdensome equipment is a good one.  In fact, that reminds me that the engine has a AC compressor system (after market probably).  The car had a long life in New Mexico - hot! It does not work (has not for a couple years the previous owner said) but is adding weight and absorbing some torque I suppose...and there isn't torque to spare.  Need to remove that also.  I don't plan to run AC, but I may keep the system just in case the NC heat beats me down one of these summers.

 

Thanks also for the thoughts on getting a shorty header.  I was wondering about this.  I looked on IE and they are out of stock.  But there is also a shorty header offered by Top Speed.  Might look into that. Otherwise, I was planning to take the manifold to a master welder I know and get the crack welded for now.  I need to read up more on the de-smogging tricks.

  

 

One note regarding Mark’s excellent de-smogging instructions: unless your ‘76 was delivered new in California, it will not have a Thermal Reactor exhaust manifold. The “outside-California” ‘76’s, known as “49-state versions”, have a more benign manifold: not as free-flowing as a tii exhaust manifold or a shorty header, but not nearly as awful as the dreaded Thermal Reactor manifold.

 

Welding a 49-state exhaust manifold, as a temporary solution to getting your car into regular use, is a good idea, as long as it’s cheaper than a good un-cracked replacement. 

 

If you provide some photos of the engine compartment, we can probably confirm whether your ‘76 is a 49-state or a California version. Below are some photos of my 49-state ‘76, especially showing the non-Thermal Reactor exhaust manifold.

 

On other matters, all ‘02 A/C is post-factory, installed at dealerships or later. The three most common brands are Frigiking, Behr (most “OEM” in appearance), and Clardy. So even the Behr unit — Behr manufactured the ‘02’s original radiators, heaters, heater valves — would qualify as “aftermarket”. Lots of threads, as well as Rob Siegel’s book on the subject, discuss ‘02 A/C in detail. Compared to modern cars, or even to U.S. domestic cars of the ‘02 era, ‘02 A/C generally sucks. But, it also expands the driving season, and often the willingness of a spouse to agree to taking “your old car”... ?

 

Regards,

 

Steve

 

Edited December 12, 2018 by Conserv

[jimk]

2 hours ago, Stevenc22 said:

They start to smoke and burn some oil but pretty happy running forever.

For a long time but not forever