AC - Delco 60G Glow Plugs

These are GM glow plugs,  I know that they fit the 6.5L GM diesel engines,  and maybe some others as well.  I first heard about the possibility of running these glow plugs in a 7.3 IDI on one of the forums,  and when I read that they are supposedly continuous duty rated I really started getting interested.

Continuous duty is understood to mean that they will burn for x number of hours without failing.    My first step was to go to O'riellys and buy one 60g plug and give it a try.  I hooked it up straight to a car battery with booster cables and let it go for 4 or 5 minutes.  The result was good and after it cooled off,  it would heat right back up again.

That made me want to try them in my 7.3.  Both glow plugs us 10mm threads,  so they will fit.......sort of at least.  The biggest  problem with 60g is that they are shorter than the 7.3 gp.  In other words, the distance between the tapered seat and the bottom of the nut is some shorter on a 60g.  So when you thread them into a 7.3 head,  the nut part of the 60g runs into the hole before the glow plug goes in far enough to seat on the taper.  And that won't work.  If you bottom the nut part out, you don't have the tapered seat seated and the glow plug is going to leak compression and the leaking gases could possibly erode away part of the gp seat in the head.

The way I altererd them to fit my 7.3 head was to grind away (lathe would be better) the lower 3/4 or so of the nut,  so it would fit down inside the head gp bore.  You can use a stock 7.3 gp as a guide to know how much length of the nut to grind down.  It worked and the glow plugs are great combined with a manual button control to operate them.

Proceed at your own risk as  there isn't much nut left to get a socket on,  and if you grind too deep and get it to thin,  the possibility is there that you could break a glow plug off in the head.

For reference, here is a picture.  The difference in length between the 2 plugs is obvious.

The Autolite 7.3 plug is on the left,  and the AC-Delco 60g is on the right.

Also as you can see in the picture, the 60g uses a spade terminal instead of the round pin type the 7.3 harness has on it,  so your looking at changing ends as well.

happy wrenchin ~ diezelcrazee