Your donations help keep this valuable resource free and growing. Thank you.
|
1969 AMX Tach - Driving me crazy |
Post Reply | Page <123> |
Author | |
musictoyz
AMC Nut Joined: Apr/17/2012 Location: cumberland, me Status: Offline Points: 377 |
Post Options
Thanks(0)
|
I am still working on this....it has to do with DI and DV tach input....I cant believe no one on the internet has a work around for Pertronics and Series Tach
|
|
1969 BBG,BBO, BBB/ 1970 Machine - www.bigbadamx.com
|
|
Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6762 |
Post Options
Thanks(0)
|
The Series or VDO tachometer states that a diode may be required to solve erratic tachometer problems - technical bulletin.
I'd phone the tach company up and ask for your specific Pertronics distributor, tachometer combination and find out what they say. My VDO had to be wired to the MSD6 box output as it would not pick up off the coil with the Motorcraft distributor.
|
|
musictoyz
AMC Nut Joined: Apr/17/2012 Location: cumberland, me Status: Offline Points: 377 |
Post Options
Thanks(0)
|
The Stock AMC Tachometer is in Series with the Coil. That's why I said Series Tach....my bad if confusing... I have done a lot of searching, this is nothing new, there are posts in every auto forum on this same subject...and no one has posted a fix. I mean 20 to 30 forums.... I did find why it happens in a Spitfire forum, as a stock points distributor to Pertronixs pointless changes the type of distributor from DI to DV...and that is the culprit.... Distributor guys want 299$ to change or mod it...but I imagine its a diode or a cap or something not that hard.
|
|
1969 BBG,BBO, BBB/ 1970 Machine - www.bigbadamx.com
|
|
Trader
AMC Addicted Joined: May/15/2018 Location: Ontario Status: Offline Points: 6762 |
Post Options
Thanks(0)
|
Have a look at this site for the Pertronics distributor with the Factory tach (GTO): From what I read the Pertronics signal is too fast and too weak for older factory tachometers. The wiring diagram has the MSD 8920 used as an amplifier for the factory tachometer. Don't know if this is a solution for you. |
|
musictoyz
AMC Nut Joined: Apr/17/2012 Location: cumberland, me Status: Offline Points: 377 |
Post Options
Thanks(0)
|
That is a start Trader.....it is definitely a Pulse Electric problem...the tach bounces or doesn't work..because the Pertronix doesn't put out a clean square wave any longer. It puts out a multi signal that is giving an old tach headache...like my old brain
|
|
1969 BBG,BBO, BBB/ 1970 Machine - www.bigbadamx.com
|
|
S Curry
AMC Addicted Joined: Aug/16/2012 Location: Iowa Status: Offline Points: 598 |
Post Options
Thanks(0)
|
My 70 factory tach w/Pertronix doesn't work too bad up to 3k. Then it just kind of floats. Compared to another dwell/tach I can hook up under the hood, they compare about the same at idle up to about 1500.I question how accurate. I am following and investigating for an answer also.
|
|
SC
|
|
musictoyz
AMC Nut Joined: Apr/17/2012 Location: cumberland, me Status: Offline Points: 377 |
Post Options
Thanks(0)
|
I am in contact with a guy in Euro that has the answers and also makes an attachment for Euro vintage cars with Pertronixs….its Volt vs Current... Guy is pretty sharp....stay tuned
|
|
1969 BBG,BBO, BBB/ 1970 Machine - www.bigbadamx.com
|
|
bigbad69
Supporter of TheAMCForum Joined: Jul/02/2007 Location: Ottawa, Ont. Status: Offline Points: 6614 |
Post Options
Thanks(0)
|
My understanding of the Pertronix conversion: Ignitor I replaces the mechanical switch with a transistor switch. Dwell is a fixed, similar to points Ignitor II has a variable dwell over 3000 RPM, but operates like an Ignitor I under 3000 Ignitor III has more smarts in it which controls the dwell at all speeds and provides a rev limiter. Reading Pertronix's FAQ, it appears the biggest issue with current sensing tachs is re-calibration. The example they use has a calibration screw on the back of the tach. The OE AMC tach does not. I have an Ignitor I in my Javelin and the tach is working, though I have not checked the calibration (yet). My guess is there is a problem with the meter movement in your tach. It might just need a bit of lubrication. |
|
69 Javelin SST BBO 390 T10
|
|
Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
Post Options
Thanks(0)
|
It also could be the caps going bad. Lots of them have a finite lifespan.
|
|
1968 AMX 390 w/T5
|
|
6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5454 |
Post Options
Thanks(0)
|
This would be helpful. I just cruised through some Ford forums (Ford used a series tach also) and they are having the same problem with the Pertronixs retrofits.
|
|
Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
|
Post Reply | Page <123> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |