Decent Lap of Thunderhill + electrical question - 460 Ford Forum
Chilly's Garage A place for non-460 banter.

User Tag List

 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 4 (permalink) Old 06-28-2009, 09:09 PM Thread Starter
Senior Member
 
Join Date: Jan 2006
Location: San Francisco
Posts: 357
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Garage
Decent Lap of Thunderhill + electrical question

I have not posted a Thunderhill "tour" for a while. This is a decent lap, though you will see the gears are too short as I had to pedal it a long way before the T1 braking zone.

You'll notice the tach is going crazy and gives up, but there is a good RPM display provided by the same source that collects the GPS and accelerometer data. It gets the RPM from the MSD just like the tach. After the lap on the video the car quit running right and we have been chasing the electrical problem. I'm interested in thoughts any of you may have. The problem is somewhat intermittent.

http://uk.video.yahoo.com/watch/5323369/14034729
Matt Robison is offline  
Sponsored Links
Advertisement
 
post #2 of 4 (permalink) Old 06-29-2009, 03:54 AM
Senior Member
 
D.I.L.L.I.G.A.S.'s Avatar
 
Join Date: Jan 2006
Location: Texas
Posts: 1,960
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
 
Vibration maybe? Or a firewall grommet that came loose letting some wire rub & ground to sheet metal? Is the coil in the driver compartment & a firewall jack used to run the coil wire through the firewall? In the past I have seen firewall jacks fry & intermittently ground the coil wire to the firewall.

D.I.L.L.I.G.A.S. Dave::
460 street '66 Ranchero.......................finished someday.
460 race '70 Maverick..........................finished someday.
All 'glass Top Sportsman '69 Mustang......ummm, check back when I win big playing the Texas Lotto, or online poker.
My youtube page. Some ancient & newer local race video.

Join the Poker Players Alliance (theppa.org). US online poker should NOT be turned into a crime.
D.I.L.L.I.G.A.S. is offline  
post #3 of 4 (permalink) Old 06-29-2009, 07:02 AM Thread Starter
Senior Member
 
Join Date: Jan 2006
Location: San Francisco
Posts: 357
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
 
Garage
Quote:
Originally Posted by D.I.L.L.I.G.A.S. View Post
Vibration maybe? Or a firewall grommet that came loose letting some wire rub & ground to sheet metal? Is the coil in the driver compartment & a firewall jack used to run the coil wire through the firewall? In the past I have seen firewall jacks fry & intermittently ground the coil wire to the firewall.

Thanks for the suggestion. It is a dual MSD setup with boxes and coils in the driver compartment and a through the firewall fitting where the coil outputs are combined. This connection looks pretty robust, but your hypothesis would explain why switching from one MSD box to the other has no effect.
Matt Robison is offline  
 
post #4 of 4 (permalink) Old 06-29-2009, 07:13 AM
Senior Member
 
Join Date: Jan 2006
Location: Cuba MO
Posts: 5,316
Mentioned: 0 Post(s)
Tagged: 2 Thread(s)
Quoted: 185 Post(s)
 
On my dyno I can make the tach operate like that sometimes if I'm running an engine with it's own ignition system like say a Chevy with a factory style HEI. I have an MSD 6 AL on the dyno and with the other system running the engine the MSD can actually "fire" even though it's pickup is not connected to anything. The EM energy produced by the secondary of the HEI will cause the MSD to trigger. I'm wondering if the extra ignition system isn't staying "on" and thus driving the tach by picking up the secondary pulses of the other ignition system......

Or it just has a bad ground at the tach and that's making it "see" many more pulses than what are really on the tach wire....

Any sufficiently advanced technology is indistinguishable from magic --Arthur C. Clarke

Dave McLain
McLain's Automotive
DaveMcLain is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the 460 Ford Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome