The Stovebolt Site Forums The Shop Area Engine Shop Tune-up replacement intervals?

Hey all,

Well I am in an unusual situation, my 41 truck with a 54 235 is all complete and running fine...all it needs is driving. Since the road salt season is upon us, there is no more driving until spring so a little self induced tinkering is at hand.

How often do you guys replace ignition parts such as distributor caps, rotors, points, condensers, and sparkplugs? My truck only goes for weekend joyrides so the miles don't accumulate that fast so I am not really wearing out parts from use. For the most part, the ignition components have been on the truck since I got it together around 2015 accumulating perhaps 1000 miles per year.

Since embarking on this truck journey, I have learned that the initial quality of the part is paramount to anything else. Good quality parts work well and cheap parts don't work so well. Recently I replaced the cheap modern vendor aluminum contact distributer cap with a nice brass contact NOS Delco Remy cap and rotor. The results were substantial. The remaining ignition parts are NOS Delco Remy or AC. Do I really need to replace points and condenser on a decent running engine? The AC plugs show a nice gray/brown burn color with no evidences of fouling and no discernible erosion on the electrodes.

Is there some point when fresh parts just perform better and it makes sense to replace them even though they are still functioning? What do you all use as a metric for maintenance replacement on a low use pleasure vehicle?

I look forward to hearing your opinions.

Oh, and happy New Year!

Paul

There is a point in time when replacement is necessary but you are very far from it. Time really has little to do with ignition parts. Usage and maintenance is the key. Check the adjustment on the points at the same time you change oil. Look over the plug wires for cracking at the same time. Inspect the inside of the distributor cap for arcing. All this can be done while the oil is draining. 30000 miles is not unusual for spark plug life with a properly tuned non oil burning engine. Keep a maintainer on the battery and StaBil in the gas for winter non-usage and come driving season you will be on the road with a big smile while the other guys are still waking their rides up.

If you like swap meets like most of us do, watch for NOS points and ignition parts so when the time does come to change them, you have a good set. I have changed spark plugs once in 20 years on my 250 with HEI ignition so I am not one to talk about maintenance.

The only thing I'll add to the above is consider Jon's new capacitor upgrade for the condenser here.. Cost is very reasonable and a condenser can partially fail and have you chasing non existent gremlins until the faulty part is finally chased down. I believe the new capacitors will help the points last longer, particularly if a condenser is less than perfect but truck still runs. My truck has always started OK only turning over a few times before firing off. But with the new capacitor one revolution starts are common.

RonR

I seem to remember 10 k miles as the recommended change interval for the ignition parts. Of course in some cases, that could take a long time.

I haven't touched my points ect in 30 years, and put 500+ miles a year on mine?

The Operator's Manual for my '48 says as part of a good engine tune-up:

"Separate the points and inspect them for being pitted or badly burned. Clean the points with a breaker point file. If the points do not clean up with a few strokes of the file they should be replaced."

It doesn't say how often this should be done.

Thanks for all of the comments.

It looks like my plan to replace all of the ignition parts at the current mileage interval may be a bit overzealous. Perhaps just an inspection and adjustment is all that is warranted at this point. It would be a shame to trash a decent working condenser as it seems that they are not that easy to find.

I recall back in my younger (poorer) days that some of the sparkplugs on worn out oil burner engines would eventually foul out and simply would not fire in spite of cleaning efforts. What makes a sparkplug quit?

Now that I have an ignition scope I will have a look at the start of every season and maybe before a long trip. This is my plan after the pandemic!

Spark plugs quit working primarily because of deposits routine cleaning can't dislodge. The ceramic insulator around the center electrode goes a long way up into the steel plug shell before it makes contact with the shell. The further the heat from the tip has to travel before dissipating itself into the cylinder head, the "hotter" a plus is said to be. On cold and medium-range plugs, carbon deposits from either rich fuel soot or carbonized oil can provide a path to ground for the firing voltage instead of making it jump the gap to the ground electrode and provide a spark to ignite the fuel/air mixture. Back in the dark ages, we used a dedicated sandblaster to clean plugs, one that blew fine pumice abrasive material all the way to the inner shell of the plug to dislodge deposits. Many years later, I used a glass bead blaster to clean race car plugs between races. I had 3 or 4 sets of spare plugs that we cleaned that way, and swapped them out while adjusting fuel mixture during practice. Those 4 sets of spark plugs would last the entire racing season, with just a cleaning between uses.

An important part of spark plug servicing is keeping the center electrode filed off square. A squared-off electrode requires about 15% less voltage to jump a spark than a rounded tip does, regardless of the plug gap involved.
Jerry

Jerry,

Thanks for taking the time to describe how a spark plug may become unserviceable. Good description! The carbonized oil sounds like what was happening on those old worn out oil burner engines of my youth. In my teenage years I bought a gimmicky motorized spark plug cleaner tool from JC Whitney that "sand blasted" the plugs. It never really fixed the badly oil fowled plugs.

From your description it sounds like the important factors to look for on a spark plug is the amount of deposits forming on the ceramic portion and erosion of the center electrode. It is presumed that using correct heat range spark plugs matching the use pattern should minimize carbon formation. Working with engines that are not totally worn out will help too!

Paul