Go Back   The Ford Barn > General Discussion > Early V8 (1932-53)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Display Modes
Old 01-27-2021, 09:49 PM   #21
JHFORD51
Senior Member
 
Join Date: Feb 2011
Posts: 232
Default Re: Runs great until it heats up

Welding with battery connected or even disconnected but with you electronic Mallory still connected isn't good. They probably killed the module in your distributor. My two cents.

Brother just did the same thing last race season on his gasser Falcon and killed his MSD box. It would crank and run, but act weird under load. He figured it out AT the track...
JHFORD51 is offline   Reply With Quote
Old 01-27-2021, 10:59 PM   #22
tubman
Senior Member
 
tubman's Avatar
 
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 7,120
Default Re: Runs great until it heats up

Run aftermarket electronic ignitions at your own peril.
tubman is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 01-28-2021, 01:49 AM   #23
koates
Senior Member
 
Join Date: May 2010
Location: Melbourne Australia.
Posts: 1,696
Default Re: Runs great until it heats up

Quote:
Originally Posted by tubman View Post
Run aftermarket electronic ignitions at your own peril.
Mr tubman, exactly my sentiments. Although I have pertronix units on my early falcon and mustang for many years and no issues. They are easy to change back to points/condenser on the side of the road. Regards, Kevin.
koates is offline   Reply With Quote
Old 01-28-2021, 05:30 PM   #24
demingboy
Junior Member
 
demingboy's Avatar
 
Join Date: Oct 2020
Posts: 27
Default Re: Runs great until it heats up

i guess you ruled out vapor lock?
demingboy is offline   Reply With Quote
Old 01-31-2021, 05:39 AM   #25
srg
Junior Member
 
Join Date: Mar 2019
Posts: 10
Default Re: Runs great until it heats up

Both idling and under load, but more pronounced under load. Haven't ruled out vapor lock. I did rule out the ballast resistor for the coil. I put a new one on, problem continues. Coil is hot enough when I got back to cause me to take my hand off of it really quick.
srg is offline   Reply With Quote
Old 01-31-2021, 07:41 AM   #26
Gene1949
Senior Member
 
Gene1949's Avatar
 
Join Date: Jun 2016
Location: Pahrump, NV
Posts: 129
Default Re: Runs great until it heats up

Sponsored Links (Register now to hide all advertisements)
Coil is hot enough when I got back to cause me to take my hand off of it really quick.

Looks like you are on the way to a solution. You've still got a problem with the mismatch of coil/resister.
Gene1949 is offline   Reply With Quote
Old 01-31-2021, 02:15 PM   #27
G.M.
Senior Member
 
Join Date: May 2010
Location: Florida and Penna.
Posts: 4,423
Default Re: Runs great until it heats up

Quote:
Originally Posted by srg View Post
Both idling and under load, but more pronounced under load. Haven't ruled out vapor lock. I did rule out the ballast resistor for the coil. I put a new one on, problem continues. Coil is hot enough when I got back to cause me to take my hand off of it really quick.
What is the voltage at the coil, points open and points closed. G.M.
__________________
www.fordcollector.com
G.M. is offline   Reply With Quote
Old 01-31-2021, 03:04 PM   #28
JSeery
Senior Member
 
JSeery's Avatar
 
Join Date: Nov 2012
Location: Wichita KS
Posts: 15,574
Default Re: Runs great until it heats up

Quote:
Originally Posted by srg View Post
Both idling and under load, but more pronounced under load. Haven't ruled out vapor lock. I did rule out the ballast resistor for the coil. I put a new one on, problem continues. Coil is hot enough when I got back to cause me to take my hand off of it really quick.
What ballast resistor and which coil are you using?
JSeery is offline   Reply With Quote
Old 01-31-2021, 06:19 PM   #29
koates
Senior Member
 
Join Date: May 2010
Location: Melbourne Australia.
Posts: 1,696
Default Re: Runs great until it heats up

No point in just guessing here and swapping around parts, you have to do some testing with a meter because your coil should not be that hot. Its hot because its drawing too much current. Measure the coil primary resistance in ohms and also the resistor which should measure up to a total of approx 3 or 4 ohms. Another way is to measure the current draw of the coil with the engine running at idle speed. Should be no more than three amps. As you rev the engine up a little the current draw should lower to maybe two amps. Regards, Kevin.
koates is offline   Reply With Quote
Old 01-31-2021, 09:07 PM   #30
JayChicago
Senior Member
 
JayChicago's Avatar
 
Join Date: Jan 2019
Location: Chicago
Posts: 199
Default Re: Runs great until it heats up

Quote:
Originally Posted by koates View Post
.....engine running at idle speed. Should be no more than three amps. As you rev the engine up a little the current draw should lower to maybe two amps. Regards, Kevin.
Kevin, can you explain this to us wanabe electrical geeks? Why is current draw less with slight increase in RPMs?
JayChicago is offline   Reply With Quote
Old 01-31-2021, 10:07 PM   #31
koates
Senior Member
 
Join Date: May 2010
Location: Melbourne Australia.
Posts: 1,696
Default Re: Runs great until it heats up

Jay, The distributor contacts or the electronic switching pick up (on an electronic ignition) in the coil primary circuit act as a kind of regulator by rapidly switching on and off and the more engine RPMs you have then the faster the switching cycle and therefore the lower current (amps) draw in the coil primary circuit. That is also how a voltage and current regulator works on your cars generator circuit. Hope you can take in that explanation. Regards, Kevin.
koates is offline   Reply With Quote
Old 02-03-2021, 10:42 AM   #32
AnthonyG
Senior Member
 
AnthonyG's Avatar
 
Join Date: May 2013
Location: Pa.
Posts: 1,712
Default Re: Runs great until it heats up

I had a similar prob early on when going w a New engine that was supplied w a resistor mounted to the Engine engine next to coil. Not thinking about it I hooked up the ignition circuit mounted on engine to the stock wire on the wiring harness for the ignition. I didn’t take into consideration that that wire already had the under-dash stock resistor in the Car wiring circuit so ended up w current going thru both resistors causing a similar problem SRG is having. Eliminated the under-dash resistor & problem disappeared.
__________________
Nomad

Last edited by AnthonyG; 02-03-2021 at 10:44 AM. Reason: Typo
AnthonyG is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump

Sponsored Links (Register now to hide all advertisements)


All times are GMT -5. The time now is 04:57 AM.