Go Back   The Ford Barn > General Discussion > Model A (1928-31)

Sponsored Links (Register now to hide all advertisements)

Reply
 
Thread Tools Search this Thread Display Modes
Old 11-03-2011, 02:44 PM   #1
31dan
Junior Member
 
Join Date: May 2010
Posts: 5
Default Spark advance or Spark retard

I'm going up a very steep hill do I advance the spark (move lever down) or do I retard the spark (move lever up) My 31 PU started backfiring today. I could fill the power coming and going. I had the gas pedal to the floor. The truck runs very good on level roads. I probably had only about 2 or 3 gallons of gas. Any help would be good.
31dan is offline   Reply With Quote
Old 11-03-2011, 03:07 PM   #2
junk yard kid
Senior Member
 
Join Date: Aug 2011
Location: san diego
Posts: 101
Default Re: Spark advance or Spark retard

Im not entirley sure. But i think i read that its bad to floor it up a hill and that you want to retard the spark a little. Its easier on the bearings.
junk yard kid is offline   Reply With Quote
Sponsored Links (Register now to hide all advertisements)
Old 11-03-2011, 03:17 PM   #3
Tim
Senior Member
 
Join Date: May 2010
Location: Aptos, CA
Posts: 300
Default Re: Spark advance or Spark retard

Make sure the timing is correct and the points and condensor are in good shape first. Then make sure it isn't starving for fuel. But an engine with a mechanical advance needs a certain amount at a given strain and RPM. You'll need to move the lever until it sounds just right. So there is no magic spot, each engine is different. Downshifting also helps with the leverage aspect of it and uses the torque properly albeit slower speeds. Too much advance and detonation, too little and the engine will overheat.
A's have the best with the mechanical levers it lets you set it where it wants to be.

Have fun,

Tim
Tim is offline   Reply With Quote
Old 11-03-2011, 03:23 PM   #4
Bruce Adams
Senior Member
 
Bruce Adams's Avatar
 
Join Date: May 2010
Location: Northport, NY
Posts: 1,097
Default Re: Spark advance or Spark retard

You want to retard it when straining on a hill.
Bruce Adams is offline   Reply With Quote
Old 11-03-2011, 03:39 PM   #5
steve s
Senior Member
 
steve s's Avatar
 
Join Date: May 2010
Location: Kalamazoo
Posts: 1,302
Default Re: Spark advance or Spark retard

Undoubtedly, retard the spark whenever the engine is laboring up a hill. Normally, you will hear the motor start to ping, knock, or make other unhappy noises like something going wrong (it is), and that's your signal to retard the spark, PRONTO! If you heard backfiring rather than knocking, I would wonder whether your car is tuned properly--even though you THINK it runs fine on the level. I would check the timing, plugs, and points, and carb float level.

But, retarding the spark on a hill is a short term fix. Like Tim said, running retarded for very long will overheat motor. Better to downshift into second, and just grind along at a lower speed. One of the aggravations with A's, is the gap between 2nd and 3rd. The motor will really be roaring at 25 mph in 2nd gear, but will labor and knock in the 25-35 mph range when pulling a steep hill in 3rd.

If still knocks in 2nd gear, then you need to downshift to low, which will require either some very accomplished double clutching or coming to a complete stop. And then you grind along at about 10-15 mph. This is why 4.11 rear ends were popular in the mountains and why the Mitchell gear-splitter OD unit is so appealing.

Steve

Last edited by steve s; 11-03-2011 at 03:54 PM.
steve s is offline   Reply With Quote
Old 11-03-2011, 09:23 PM   #6
Marco Tahtaras
Senior Member
 
Marco Tahtaras's Avatar
 
Join Date: May 2010
Posts: 2,791
Default Re: Spark advance or Spark retard

Modern vehicles have an automatic advance relative to speed and other conditions. Generally, the greater the engine RPM the greater the advance.

Now most Model A owners don't feel the strains which are very similar to needing to down shift. They simply start the car, fully advance the spark. and go driving. I decent Model A with stock compression will survive this just fine most of the time ON FLAT GROUND. Putting it under a load such as towing something or climbing a hill makes the timing relative to engine speed more important.

With additional compression (high compression head) it becomes even more critical for two reasons. First, the increased pressure places additional stresses on the lower end. Second, higher compression increases the burn rate of combustion. That means it responds quicker to the firing of the spark plug which in essence means it advances the timing somewhat all by itself, so you must compensate slightly with the spark lever.
__________________
http://www.abarnyard.com/
Marco Tahtaras is offline   Reply With Quote
Old 11-04-2011, 06:42 PM   #7
Milton
Senior Member
 
Milton's Avatar
 
Join Date: Oct 2010
Posts: 837
Default Re: Spark advance or Spark retard

Consider a modern car as it comes to an upward incline. The initial response from the engine as it loads is to experience a lower vacuum which retards the timing a given amount. As the load increases even more, the rpm will lower and the centrifugal weights will collapse towards the center shaft and increase the retardation. A downshift will reset the process somewhat in that the increase in rpm will cause the weights to move outward and increase the advance. So your action on an incline is to copy this sequence. I live at the top of a three mile grade so I used to get a lot of practice. When the loading begins I bump up the lever 4-5 degrees and increase the throttle. If the load continues and the rpm lowers I re-adjust until the rpm becomes steady. If it continues I will downshift, bump the advance and go through the adjusting again. If the rpms continues to drop I will turn around, restore the advance, go down and then go around.
Milton is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 03:10 AM.