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9000 rpm tach
Posted: Sat May 21, 2011 7:57 am
by dsm2002
Re: 9000 rpm tach
Posted: Sat May 21, 2011 8:09 am
by dsm2002
BTW It's for a M42 with bigger inlet and exhaust valves, Schmitthelm valve springs, Schrick Ti retainers, Catcams cams, mechanical lifters. Schmitthelm valve springs were being run in 6R4 metro and DFV Cosworths. They were reving the 6R4 metro with these springs to 13500 safely.
8500rpms will not be out of the question.
Re: 9000 rpm tach
Posted: Sat May 21, 2011 10:30 am
by Dave_M3
And you'll probably make fookall more power from 7000 onwards only noise
Nice idea though! I think there's a little too many lines on it though, 500rpm segments may be enough like the original.
If an E30 M3 cluster was used as the range is a little closer to fit 8K on the binacle and the oil-temp gauge section is alot smaller than the mpg guage on the normal clusters, you could add in the 9K very easily without having to get rid of the oil temp section.
you also could rotate the needle anti-clockwise on the shaft a little and move the stop, you'd then be able to balance the graph around the binacle better and it would look very original looking
Probably easier to just show you what i mean about the extra space just with a picture

Re: 9000 rpm tach
Posted: Sat May 21, 2011 11:50 am
by newt
could you fit a 6pot coding plug, then adjust the dial to suit? due to the coding plug say 6000rpm would read 4000rpm am i right? then the needle wouldnt spin around as far

Re: 9000 rpm tach
Posted: Sat May 21, 2011 3:04 pm
by e301988325i
newt wrote:could you fit a 6pot coding plug, then adjust the dial to suit? due to the coding plug say 6000rpm would read 4000rpm am i right? then the needle wouldnt spin around as far

This is correct and a good idea. tacho will read 2/3rds with a 6pot coding plug fitted.
The lines should be a similar spacing to the speedo lines for it to look OEM IMHO.
Re: 9000 rpm tach
Posted: Sat May 21, 2011 3:25 pm
by Dave_M3
e301988325i wrote:newt wrote:could you fit a 6pot coding plug, then adjust the dial to suit? due to the coding plug say 6000rpm would read 4000rpm am i right? then the needle wouldnt spin around as far

This is correct and a good idea. tacho will read 2/3rds with a 6pot coding plug fitted.
The lines should be a similar spacing to the speedo lines for it to look OEM IMHO.
Be nearly good for a 10K redline then

Re: 9000 rpm tach
Posted: Sat May 21, 2011 4:13 pm
by dsm2002
Dave_M3 wrote:And you'll probably make fookall more power from 7000 onwards only noise
Nice idea though! I think there's a little too many lines on it though, 500rpm segments may be enough like the original.
If an E30 M3 cluster was used as the range is a little closer to fit 8K on the binacle and the oil-temp gauge section is alot smaller than the mpg guage on the normal clusters, you could add in the 9K very easily without having to get rid of the oil temp section.
you also could rotate the needle anti-clockwise on the shaft a little and move the stop, you'd then be able to balance the graph around the binacle better and it would look very original looking
I'd love to get an M3 gauge. They are rare down here in Australia.
I also am hoping it'd make more that noise over 7000. Quite a deal of work has been done on ithe head. The flow figures are:

Re: 9000 rpm tach
Posted: Sat May 21, 2011 4:25 pm
by Dave_M3
NICE!!!
I'm building an M42b21 using S54 ITBs for my iS so going to have to do alot of work to the head too but 7.5-8K from the M3 clocks will be more than enough for me I think :p
Re: 9000 rpm tach
Posted: Sat May 21, 2011 4:38 pm
by CHR1S1990
Dave_M3 wrote:NICE!!!
I'm building an M42b21 using S54 ITBs for my iS so going to have to do alot of work to the head too but 7.5-8K from the M3 clocks will be more than enough for me I think :p
s42 ftw

Re: 9000 rpm tach
Posted: Sat May 21, 2011 4:48 pm
by Dave_M3
Indeed!!!
If you have a spare 25K

Re: 9000 rpm tach
Posted: Sun May 22, 2011 2:58 pm
by dsm2002
If an E30 M3 cluster was used as the range is a little closer to fit 8K on the binacle and the oil-temp gauge section is alot smaller than the mpg guage on the normal clu
Looking further into this, I was wondering if an M3 coding plug with a replica M3 facia is all that is needed to convert a e30 tach.
Fixed!
BTW how do coding plugs work? What's their circuit?