early guages

[roundtail]

Question: Can early "silver dollar" style guages be used in the later 02s (like my 73')?

[Son of Marty]

Answer, Yes.

[roundtail]

Thanks Marty

[Mike Self]

The only caveat:  make sure that early "silver dollar" speedometer isn't from a 1600, or it'll have the incorrect gears for the 02's 3.64 differential.  Check the ratio stamped on the back side--should say W=1.297 for a 3.64; a 4.11 will say W=1.4.

 

mike

 

 

[NickVyse]

Mission creep - changed speedo, needed quicker diff ratio 🙂

[Joesprocket]

If anyone has a spare silver dollar tach I'm in the market for one that's gone missing from my early cluster.

Stamped with W=1.297 for my 3.64. 

 

Thanks in advance.

[roundtail]

Thank you Mike! As always the definitive answer. Looking to put together a retro guage pod set up for the 73' and just wanted to make sure the speedo & tach I have will work.

[Tom Daley]

Hi, I have a few questions for the group about gear ratios,

 

      1) Can I change my speedo cable drive gear to correct for my slightly smaller circumference tires and probable diff gear change? Is anything available? In my earlier muscle car days I remember colored drive gears.

 

     2) If I recall correctly my research in the FAQ showed calculated RPM drop from 390s to 364s is 400. I extrapolated on that as 675ish for 390s to 345s. My question is, from everyone's experience, which is preferable for normal to spirited street driving w/an occasional track day? On the workbench my e36 345s look like exactly like the '02 364s. 

 

1976, fresh stock lower end at 8.2:1 with a 374deg/+2mm lift cam, stock manual 4 speed.  Synchronized 32/36 jetted by AF/O2 gauge, peanutted manifold, UNPLUGGED power valve & secondary enrichment circuit, Fresh E12 head w/manifolds ported/flowed. Heat wrapped down pipe.

 

Pulls hard at any RPM and wants to keep going through redline, definitely room for a shorter gear. (Oh, I almost forgot, subjective I know but how far past redline will a tightly built M10 tolerate?)

 

Thanks Tom

[Preyupy]

There are no alternate speedometer drive gears all of the adjustments were made at the speedometer.  The only option would be to modify the cable and install a "gearbox" that will alter the ratio.  

 

As far as RPM the real restriction will be your rocker arms.  With an altered cam what did you do with the valve springs?  The stock rocker arms will not last very long if you even think of floating the valves.  Some of the aftermarket "stock" rocker arms are total junk and I would never use them in anything.  That being said I spent a lot of time at closer to 7000 rpm with a stock engine back in my autocross days without any catastrophes (45+ years ago).     

[TobyB]

My experience (at Spokane) is that the sustained safe limit for stock valve springs is about 6800.  Much over that,

and you are not permitted to lift off the throttle, as an intake rocker will snap.  I DID find that with just the right springs,

even the worst of the voidy Febis (BMW M10 rockers are now Febis with voids with a roundel on them)

hold up to about 7400- but again, once you're there, you can't let the throttle snap closed.

 

But there's not any real reason to go there- the stock parts are over the top by 6200 or so.

(what cam do you have?  274?) so while you may gain a bit in the 2-3 shift, otherwise,

use the torques of the M10 to best result.

 

[ray_]

On 3/25/2024 at 9:48 AM, roundtail said:

Thank you Mike! As always the definitive answer. Looking to put together a retro guage pod set up for the 73' and just wanted to make sure the speedo & tach I have will work.

The other caveat is that in my experience I have found that the mounting studs on the silver dollar assembly are shorter. 

[Tom Daley]

Yes, 274 w/2mm added lift. Stock arms and springs, I'll stay at 6200ish.  Thoughts on 345s vs 364s?  Thanks all!