Plastic Runner restoration

[mvliotta]

All for keeping the plastic runners on the car!

They are really not that troublesome. I’ve confirmed no air leaks with a homemade smoke machine. If/When they crack, replace with a spare. 

I have spares that I intend to work on soon...hoping to remove scuffs and shine up. Was thinking a combo of steel wool and polishing compound might do the job. 
 

Keeping tabs of this thread in case anyone has a better idea on how to restore them. 

[Conserv]

13 hours ago, tomphot said:

... But if they don’t work…….

 

They do work, Tom. But at a time when the cars were daily drivers, adding 15K miles annually, the number of failures was simply too high for a non-wear component. BMW was replacing them during and after the warranty period and had to be saying to themselves, “We’ve just begun production of a premium-priced sub-model that promises to be very popular. Do we really want to spend the next ten years replacing plastic runners? It’s bad economics and bad brand image.” The answer was clearly no, and the majority of tii’s were produced with the more expensive aluminum runners.

 

As Ted (@Einspritz) noted, many failed after a lot of miles; some cracked during the installation process. But I’d bet the majority of surviving runners, as in 50% or more, are the original units.

 

Best regards,

 

Steve

 

[ray_]

3 hours ago, NickVyse said:

I've been told, but don't have first ear verification, that a tii sounds better with the plastic runners. Makes sense.

 

My '72 will certainly be keeping them if I ever get round to finishing it - there will be a point where they had 10k to the value, or are we there already?  ?

Someone should re-make them out of carbon fibre! 

 

?

[Conserv]

Looking great, Vince!
 

[irdave]

13 hours ago, chargin said:

Top End Performance sells a Black Steel replacement set 

 

Yeah, no.  I like most of what TEP sells, but those don't work right- totally change the intake, you can easily feel (like all y'all could feel it) the death of the surge of the tii up top.  Stock tii, you can feel it come 'on the pipe.'  When using the TEP parts that's no longer there, and it's not thicker everywhere, it just looses the hit up top.

 

The plastic ones can work, you just have to be careful installing them.  And there are plenty out there- when I sold my car it had an extra 4?, maybe 6 tubes...

[irdave]

6 minutes ago, ray_ said:

Someone should re-make them out of carbon fibre! 

 

?

 

Fuck yes.  Dude.  If I still had my tii I'd be on this path.

 

d.

-obviously not needing originality

[Lorin]

2 hours ago, ray_ said:

Someone should re-make them out of carbon fibre! 

 

?

Hell yes. 
 

And maybe a carbon Tii air box to match  !

[Einspritz]

Here's another thought to keeping the OE plastic runners:

 

The volume of the plenum and the runners are different than the cast pieces. In addition, the plastic runner cars had  a different head, CR, and injection pump fuel curves than the later cars. These all work in concert to provide a slightly different harmonic at various engine speeds and thus different positive pressure (over 14.7 psi) to the intake charge at and above peak torque. It is not much different, but it is.

 

Yes, you can, and I have, changed to an E12 head, but you then need to change pistons and the injection pump fuel curves to accommodate that because the knock frequency changes, and all those "combustion considerations" as well depending on the fuel you use.

 

So, if you want to change one component, then you must calculate the effects of your decision on the SYSTEM, and adjust accordingly, otherwise, don't muck up the engineering. Or just like so many back in the day who didn't understand the Tii, ......install (ugh) sidedrafts.

[Conserv]

1 hour ago, Einspritz said:

... the plastic runner cars had  a different head, CR, and injection pump fuel curves than the later cars...

 

Ted,

 

Certainly, yes, the heads changed, as well as the intake manifold, runners, and plenum. CR did not change on U.S. cars, however: it stayed at 9.0. As to the fuel curve of the Kugelfischer, I’m aware of a fuel curve change that occurred with the 1974 model year (VIN 2780001 for U.S. cars). This was reportedly done to improve emissions, as U.S. emissions standards increased for 1974. But I’ve not yet heard of or seen a fuel curve change with VIN 2761944 (along with a reversion at VIN 2762015, and a second change at VIN 2762373). The Euro-spec cars were converted on yet another schedule, making the global changeover even more complex.

 

Your thoughts on a fuel curve change with the head change could certainly be true. It makes sense. I’m just saying I’ve never heard of it previously. And although this forum has fussed on many occasions with the issue of exchanging Kugelfischer pumps between 1974 models, on one hand, and 1972-73 models, on the other hand, I’ve not previously seen a similar fuss between 121 head cars and E12 head cars.

 

I, and probably others, would love to know more about this. How can we know whether a pump is a 121 curve or an E12 curve?

 

I’ll start. My ‘73’s original pump (VIN 2762757, manufactured October 19, 1972) has a housing cast in June 1972, and is number 92004011 B-1 / 1 [maybe 2] W 00325 (first two photos). My spare pump (this came off another ‘73, one I would guess was manufactured in late 1972 or early 1973) has a housing cast October 1972, and is number 92004011 B-1 / 3 W 01787 (second two photos). Strongly believing that both these pumps were designed for E12 heads, what do we see in the model and serial numbers of this and other 1972 (and certainly 1971) Kugelfischers that might allow us to distinguish 121 pumps from E12 pumps?

 

Thanks and best regards,

 

Steve

 

[Einspritz]

Steve;

 

OK, so now we are on track to elucidate a big ol matrix of Serial numbers of the production, the engine whether US or Euro, the type of heads, CR, injection pumps' model, and fuel output curves.

 

Yes?

 

Alright, you sucked me into the vortex, because now I am really curious, but I'm gonna have to have some time to look at my references and perhaps measure everything again, because well, the memory doesn't always serve me as factual and I try not to succumb to loose conjecture.

 

And sometimes I can't remember between the Tii, the Turbo, or the S14.

 

What was the question? :)

 

With all that, I can then run the numbers as far as trapped compression ratio and all that other fun mathematical stuff to really see what the differences are from a theoretical point.......bench engine building.

 

I'll dig out my spare pumps and record that information, but may not necessarily have the associated VINs; casting dates may give a clue.

 

I think the weeds in the yard will have to wait to be pulled............... I REALLY wanted to do that in the hot sun, 'cause it is SO Zen, but don't worry because they always "make more"!

 

Ted

[tomphot]

7 hours ago, mvliotta said:

All for keeping the plastic runners on the car!

They are really not that troublesome. I’ve confirmed no air leaks with a homemade smoke machine. If/When they crack, replace with a spare. 

I have spares that I intend to work on soon...hoping to remove scuffs and shine up. Was thinking a combo of steel wool and polishing compound might do the job. 
 

Keeping tabs of this thread in case anyone has a better idea on how to restore them. 

Yours is the first engine bay I’ve seen that also has this extra diagnostic port!

 

[tomphot]

2 hours ago, Conserv said:

 Strongly believing that both these pumps were designed for E12 heads, what do we see in the model and serial numbers of this and other 1972 (and certainly 1971) Kugelfischers that might allow us to distinguish 121 pumps from E12 pumps?………….

 

First 2 pics are in the car, second 2 pics is my spare.

Edited May 7, 2021 by tomphot

[SydneyTii]

I have just been through this as I was finding it difficult to get a type C pump.

What I did discover is that the type B & C pumps are functionally the same, it appears that there are just cosmetic differences between the pumps, one that stands out is the enrichment return lever. The B pump return is via a spring to a lever mounted by the dipstick and the C is a push return via a spring on the WUR.

The Jaymic workshop said that they have used B & C types interchangeably without issue. I believe there is a pump on later US cars? which is different and of course there is the Turbo.

There is a change in the throttle body at some stage but I don’t know what that relates to.

Jaymic did manage to get me a type C pump so I never tested the theory. HTH.

[Conserv]

2 hours ago, tomphot said:

Yours is the first engine bay I’ve seen that also has this extra diagnostic port!

 

Vince and you are ready to truck on down to the local BMW dealership to get your primary wiring checked on that super-duper, fancy-schmancy, space-age diagnostic computer! Oh, wait, those were discarded by 1982... ??☹️
 

Regardless, the ports look fabulous!

 

Best regards,

 

Steve

 

[Conserv]

3 hours ago, Einspritz said:

Steve;

 

OK, so now we are on track to elucidate a big ol matrix of Serial numbers of the production, the engine whether US or Euro, the type of heads, CR, injection pumps' model, and fuel output curves.

 

Yes?

 

Alright, you sucked me into the vortex, because now I am really curious, but I'm gonna have to have some time to look at my references and perhaps measure everything again, because well, the memory doesn't always serve me as factual and I try not to succumb to loose conjecture.

 

And sometimes I can't remember between the Tii, the Turbo, or the S14.

 

What was the question?

 

With all that, I can then run the numbers as far as trapped compression ratio and all that other fun mathematical stuff to really see what the differences are from a theoretical point.......bench engine building.

 

I'll dig out my spare pumps and record that information, but may not necessarily have the associated VINs; casting dates may give a clue.

 

I think the weeds in the yard will have to wait to be pulled............... I REALLY wanted to do that in the hot sun, 'cause it is SO Zen, but don't worry because they always "make more"!

 

Ted

Ted,

 

I just want to make certain that someone besides me is worrying about all these 50-year-old details of questionable value. You’re obviously on the job! ?

 

Thanks and best regards,

 

Steve