I'm thinking I ought to replace my LG4 coil, cap, and rotor when I freshen up the plugs and wires. This stuff is all original from 1984. I seem to recall reading that the stock coil/cap/rotor is weak on the LG4 305 setup. Is this true, and would coil-cap-rotor replacements be good maintenance at this point, or must I also replace the ignition module and parts in the distributor housing (basically at that point just getting a whole new distributor). Good idea or leave well enough alone if it still works fine? If I do replace anything, it must appear stock or nearly stock.

Thanks for your opinions/comments.

 

The cap & rotor are routine maintenance, the coil and module are known weaknesses.

If all are original, the cap & rotor are probably way overdue. The coil and module are typically only replaced when indicated by poor performance.

 

As Five7kid stated the cap and rotor are due for replacement especially if you don't know when,or if,they've ever been replaced.Get a good quality cap/rotor with brass contacts.You can transfer your coil to the new cap but make sure to install the rotor button/spring and use dilectric grease on the insulator pad under the coil.You can upgrade the coil while still retaining stock appearance since the dust cover hides it.

 

Thanks, guys. From your advice I will plan to replace the cap and rotor at this point. I would assume that coil/module "performance problems" amount to a bad running engine from diminishing or crappy output voltage from the coil?

 

Usually rears it's ugly head under hot conditions, and when most inconvenient. Often gives warning, though, before failing completely. But, it doesn't turn on the SES light or set trouble codes.

 

Good to know!

 

As I said I am def. replacing the distributor cap and coil, however I am also browsing the coil & ignition module parts for reference at the same time. I like to get most of my parts at Napa when possible. When choosing coils and ignition modules, I basically have two choices, identical parts but one is more than twice as expensive as the other:

NAPA Ignition Control Module MPE-TP47SB - $29.99
NAPA Ignition Control Module ECH-TP47 - $71.99

My Spidey sense warns me that the $30 special must be junk ... but what could be so different about the two to justify the price? Is this not just a fairly straightforward solid state device?

A similar situation exists with the coil:

NAPA Ignition Coil #1 MPE-IC19SB - $19.99
NAPA Ignition Coil #2 ECH-IC19 - $56.49

Holy cow! I guess #2 must come in gold lined packaging and a lifetime guarantee? Pictures look the same to me! What's the difference, besides the el-cheapo having the 'SB' suffix?

Last but not least ... the distributor capacitor. Does this thing go bad too?

 

Although I don't have any direct experience with these particular NAPA brands, the less expensive pieces are stock replacement, the more expensive are upgrades. You might get by with stock replacement, but if you'll ever do things to upgrade this engine so it will spin past 4500 RPMs, you'll want the upgrade pieces. The prices are in line with what you'd spend for Accel or Mallory upgraded parts.

I've never heard of the capacitor going bad.

 

Thanks, makes sense. No engine upgrades intended anytime in the near future. I'll keep this in mind when I consider buying a new coil and module.