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this is on my civvy power wagon, but probably the same stuff applies.

started with a 52 power wagon, not sure if it was the 218 or 230 engine, got a rebuilt "drop in" engine off ebay and it turns out to be a 251, with a different bell housing. real similar, but not quite the same. so i had to use the old bell housing, to make it all bolt to the transmission, but the old bellhousing spaces the new starter too far away from the ring gear, so they just barely catch, and grind.

i am attempting to install the old ring gear on the new flywheel, but i'm having a hell of a time doing it. cleaned all the burrs off the flywheel, kept it in the freezer for an hour, heated the ring gear in the oven at 350 for half an hour, cannot get it to start.

filed a any spots that looked high on the flywheel, cleaned up the bevel on the ring gear with a grinder, still can't get it started. is there a chance the two ring gears aren't the same size? they are REAL close, but so far i just can't get it started. even built a jig with a bunch of clamps, but of course now my torch is out of fuel...need a new bottle of fuel and i'll keep trying with the clamps and heating with the torch as i go. just need to get it started and i think i can get it to go the rest of the way. unless they made two different sizes of ring gear seats. in which case i'll probably grind out the inside of the gear till i can get it to fit, and then just tack weld it in place to make sure it can't pop loose.

i guess really my question is, is the 146 tooth and the 172 tooth ring gear interchangeable with each other? and if so, do i just need to bake the ring at a higher temp? i read somewhere not to go more than 400 degrees. i can also try leaving the flywheel in the freezer overnight instead of just for an hour, maybe that would help

any ideas?

thanks for all the help!

got it! what should have taken 20 minutes ended up taking me 7 hours. here's what i did, for anyone else interested in doing the same thing

clean the flywheel with a file. i just used the square end of the file and used it to scrape all the old rust off the surface, so everything was shiny. this also shows you any high spots that might be a problem. it was easy to spot the places where the flywheel had been buggered, and smooth them up with a few light strokes with the file.

then, take a wire brush on a small grinder and REALLY clean the ring gear. i used some sandpaper and made sure it was extremely shiny. i might have taken more than i needed to but i was getting tired of it not going, and i built a gauge block to compare it to the size of the ring that had come off, and it was slightly smaller, so i didn't feel too bad about making it shiny. plus i'm probably going to tack weld it to make sure. maybe unnecessary? do these ever slip?

then, freeze the flywheel for at least two hours. before i had only froze it an hour and i could tell that 2 hours made it colder the second time.

bake ring gear at 450 for 30 minutes. i read somewhere not to go over 400, but that wasn't working for me. maybe this next part is why...

i had the flywheel sitting outside on a heavy wooden bench, to drift the ring on once it got started by heating it. it's a hot day for here, in the 70's, but the wind is blowing pretty good. i'm guessing that in the 10 seconds it took to run outside with the ring, it was cooling too far and wouldn't drop like it was supposed to.

the last time, i put the flywheel on the kitchen counter, less than 2ft from the oven door, so i could IMMEDIATELY take the ring out of the oven and drop it on the flywheel. this time, it dropped all the way on. no friction at all. just dropped to the bottom, bounced, and stuck. i used a drift to drive it down the last few mm, but that was only because the ring was slightly warped from me trying to force it on all afternoon without having it hot enough.

hope this helps some of you guys, once i did it correctly by having the flywheel right next to the oven, it was totally effortless.

Good info, thanks for sharing it.

DDG