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89 Alfa 75
Alfa Arna
Joined: 25 Sep 2013
Posts: 11
Location: Dunedin New Zealand
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 Posted: Sat Sep 28, 2013 4:30 am Post subject: rev counter info please |
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Hi all, I got the 33 road legal yesterday, when I was driving it I noticed the rev counter only indicated between a half and 2/3 the actual revs? I checked the distributor pick up and it looks ok and the connection on the back of the gauge is ok? What could the cause be? Will I need a new set of gauges?
Cheers
Adam 
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1989 Alfa Romeo 75 twinspark, Alfa Romeo 33 1.5ie |
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eagle3
Alfa 33
Joined: 11 Nov 2007
Posts: 402
Location: France
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| Posted: Sat Sep 28, 2013 10:40 am Post subject: |
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Probably a faulty rev counter.
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Alfa33 QO 1984
Alfa33 1.3i.e. 1994 |
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LoneWolf33
Alfa Arna
Joined: 21 Sep 2013
Posts: 22
Location: Budapest, Hungary
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| Posted: Sat Sep 28, 2013 3:26 pm Post subject: |
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There is a variable resistor inside the rev counter mounted on the PCB,
which is often fails, causing lower readings (usually after 6-10 years).
It's cheap to replace, but the rev counter needs to be calibrated then.
I was need to do this on my both 33s. |
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89 Alfa 75
Alfa Arna
Joined: 25 Sep 2013
Posts: 11
Location: Dunedin New Zealand
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| Posted: Sat Sep 28, 2013 7:20 pm Post subject: |
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So its not un common for them to break then? Thanks for the info, is it possible to get the resistor from a automotive electrical supplier? Cheers 
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1989 Alfa Romeo 75 twinspark, Alfa Romeo 33 1.5ie |
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paulhide
P4
Joined: 20 Dec 2003
Posts: 1607
Location: Oh Beautiful Billingham
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| Posted: Sat Sep 28, 2013 8:04 pm Post subject: |
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May not be the answer, but before you do anything just check that the needle hasn't warped a little in heat and then dragged on the screen. Happened to me once - cut the end of the needle and all was fine.
Oh, only useful for series 1/2 clusters 
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Owner's Club 33 Registrar. Now from P4 & S2 1.7 QV
http://www.alfa-pages.co.uk/viewtopic.php?t=5188
Last edited by paulhide on Tue Oct 01, 2013 7:28 am; edited 1 time in total |
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LoneWolf33
Alfa Arna
Joined: 21 Sep 2013
Posts: 22
Location: Budapest, Hungary
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| Posted: Sat Sep 28, 2013 9:22 pm Post subject: |
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| So its not un common for them to break then? |
I was bench tested 4 or 5 instrument cluster from the post '90 serie,
not counting mine, and the rev counter was inaccurate in all of them.
(250 to 500 RPM difference in the actual readings @ 3000 RPM, and the reading difference is growing with the RPM)
Maybe I just wasn't lucky...
| Quote: |
| is it possible to get the resistor from a automotive electrical supplier? |
I think automotive electrical suppliers may not have this kind of stuff,
but here's an example for a store and a suitable part (if my memory serves me right regarding the value):
http://www.surplustronics.co.nz/products/1702-200-ohm |
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89 Alfa 75
Alfa Arna
Joined: 25 Sep 2013
Posts: 11
Location: Dunedin New Zealand
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| Posted: Tue Oct 01, 2013 4:24 am Post subject: |
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Thanks for the link, mine reads 3500rpm when the rev limiter kicks in so I think I will try to find a replacement cluster.
Does the pickup on the distributor run off the rotor arm? Cos I noticed mine has a big burn hole in the centre and looks cracked, which could also explain the stutter when pulling off? I tried taking the rotor arm off but can't get it off.
Is there a trick to removing them? Cheers
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1989 Alfa Romeo 75 twinspark, Alfa Romeo 33 1.5ie |
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paulhide
P4
Joined: 20 Dec 2003
Posts: 1607
Location: Oh Beautiful Billingham
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LoneWolf33
Alfa Arna
Joined: 21 Sep 2013
Posts: 22
Location: Budapest, Hungary
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| Posted: Tue Oct 01, 2013 9:50 am Post subject: |
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| Do the IEs have same clusters as 16v cars, anyone ?? |
The speedo of the 16V models is scaled to 240km/h (instead of 220) and the
redline mark is higher on the rev counter, but from electronic and mechanical point of view they're interchangeable. |
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LoneWolf33
Alfa Arna
Joined: 21 Sep 2013
Posts: 22
Location: Budapest, Hungary
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| Posted: Tue Oct 01, 2013 10:10 am Post subject: |
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| Is there a trick to removing them? |
Due surface corrosion of the upper section of distributor shaft, it's often hard remove the rotor arm.
You can try to lift off the dust cover as far as it go, apply some WD-40 on the shaft,
and put a suitable wrench between the trigger wheel and the cylindrical bottom of the rotor arm,
and gently lift the arm by the wrench. |
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paulhide
P4
Joined: 20 Dec 2003
Posts: 1607
Location: Oh Beautiful Billingham
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| Posted: Tue Oct 01, 2013 2:20 pm Post subject: |
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Cheers LoneWolf, I've got one here for sale, but I've got a feeling postage to NZ these days would be pricey.
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Owner's Club 33 Registrar. Now from P4 & S2 1.7 QV
http://www.alfa-pages.co.uk/viewtopic.php?t=5188 |
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LoneWolf33
Alfa Arna
Joined: 21 Sep 2013
Posts: 22
Location: Budapest, Hungary
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| Posted: Wed Oct 02, 2013 7:07 am Post subject: |
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| Quote: |
| Cheers LoneWolf, I've got one here for sale, but I've got a feeling postage to NZ these days would be pricey. |
Thank you for the offer. Regarding the postage I agree, probably it would cost more than the cluster itself...
After seeing the other used (and inaccurate) rev counters, I was repaired the original instruments.
BTW: are the 33s were marketed with MPH scale on the speedo in NZ? |
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paulhide
P4
Joined: 20 Dec 2003
Posts: 1607
Location: Oh Beautiful Billingham
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89 Alfa 75
Alfa Arna
Joined: 25 Sep 2013
Posts: 11
Location: Dunedin New Zealand
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| Posted: Wed Oct 02, 2013 8:12 am Post subject: |
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Hey, I think the s1 33 had mph soeedos but mine is kph, I got a quote to get it re calibrated after fixing at $300  I've found one but not sure jf it works correctly as it's 4 hours drive away  thank you for the offer on the cluster. I can always get my old man to post me one. He lives in worcester.
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1989 Alfa Romeo 75 twinspark, Alfa Romeo 33 1.5ie |
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