My '85 MGM, "Maisa"

[sly]

That's reassuring. At least there's no 10mm socket that escaped inside there.

[Arquemann]

That's reassuring. At least there's no 10mm socket that escaped inside there.

I don't think I've needed a 10mm on this car since I removed the ECM the last time. Good thing as I dropped a 10mm between the inner fender and firewall that time and 2 years later still haven't gotten it out.

[Arquemann]

302 is out again, went quick and smooth(er) this time. Apart from having done it recently, this time I unbolted the engine mount ears off the block instead of removing the engine mount crossbolts. This way I didn't have to raise the engine much at all before being able to slide it off the converter studs. Might be worthwhile doing upon reinstall, though lining up the engine ear bolts instead of dropping onto the mounts normally might be a tad harder.

Tomorrow I'll tear into the engine. Now, I need a beer.

[Arquemann]

Engine is all apart, except heads are still on and pistons in the bores.

Didn't think I could set possible failures in any order, but I'm pretty sure I got the worst possible outcome:

SPOILERI cannot find a single thing wrong inside the engine, nothing. All bearings look fine, tiny bit of wear from whatever trash in the oil, wrist pins feel fine by hand, can't rock the pistons in the bore at all, rockers were tight, lifters are fine

What caused it is a total mystery, any ideas would be appreciated.

[gadget73]

I doubt it would cause any noise, but did you swap the distributor for one with a steel gear when you did the roller cam swap? That will make sparkly bits.

Something else I have seen when using non-stock oil pump drive shafts (not sure if yours is using one) is the fancy ones are not hex all the way down, only at the end. Some distributors will bottom out on that shoulder and instead of allowing the pump shaft to float a little, it loads the gear against the distributor and pushes down on the inside of the oil pump. That could also cause some glitter. I think thats mostly a problem with TFI distributors. I know I shaved one down for John for his 351 to fix that issue. usual sign is the distributor won't quite bottom out but if you have the pan off you can verify by just trying to move the pump drive shaft. It should allow a little movement with the distributor in place.

[Arquemann]

I doubt it would cause any noise, but did you swap the distributor for one with a steel gear when you did the roller cam swap? That will make sparkly bits.

Something else I have seen when using non-stock oil pump drive shafts (not sure if yours is using one) is the fancy ones are not hex all the way down, only at the end. Some distributors will bottom out on that shoulder and instead of allowing the pump shaft to float a little, it loads the gear against the distributor and pushes down on the inside of the oil pump. That could also cause some glitter. I think thats mostly a problem with TFI distributors. I know I shaved one down for John for his 351 to fix that issue. usual sign is the distributor won't quite bottom out but if you have the pan off you can verify by just trying to move the pump drive shaft. It should allow a little movement with the distributor in place.

Yeah I got a steel gear dizzy for the roller cam indeed. Gears on both cam and dizzy are fine. Stock pump shaft and a Melling pump, distributor plonked home nicely, I doubt there's any issues with shaft length. I'm pretty confident that all the glitter in the oil was just the freshly honed cylinder walls and new piston rings wearing in, at this point I'm not worried about the glitter, since the bearings are fine. It's just the damn rattle...

So, it's not:
- bearings
- valvetrain
- timing chain
- spark knock
- accessory drive

And most likely not:
- wrist pins
- piston slap
- anything loosely bolted (ie flexplate, TC, mounts)
- exhaust leaks

Recap: first ~30 minutes after first start the engine ran smooth and quiet. Second start I had nr. 6 & 8 plug wires switched, barely ran for about 15 seconds, coughed into intake. Third start with correct firing order, dropped off high idle and started rattling, still ran smooth.

Would be pretty wild if my trans went out at the same time I got my engine redone, but the it didn't sound like it came from the trans and what the heck would rattle inside an AOD. The trans also worked fine for the 25m I moved the car.

[sly]

just for giggles, since I'm currently dealing with this issue, check the teeth on the flex plate and make sure the starter isn't dragging on it (starter gear not retracting all the way).

[gadget73]

thats a good thought. Those aluminum plates around the bottom of the bellhouse can rattle too if they are loose or bent in a funny way.

you do have the aluminum spacer place on the back of the block right?

[Arquemann]

Well, I found a problem, probably not the problem.
The ring gear isn't on straight, there's about 2mm of axial runout. The teeth are a bit worn all around, but look about the same as before the engine rebuild. Starter gear looks alright. The big spacer plate has no marks of anything hitting it (except the bit that was there previously). I haven't really had any starting-related issues, mostly bendix not throwing out and just freespinning.

Dad has some flexplates stashed, I'll see if I find a match for mine, but if I can't find one, I'm not sure if the ring gear is an actual problem to be dealt with.

[Arquemann]

but if I can't find one, I'm not sure if the ring gear is an actual problem to be dealt with.

Went through dads flexplates, one matched, but the teeth were in worse condition. And all 3 of them have the ring gears more or less crooked than mine, so I decided I'm not gonna worry about it.

[gadget73]

I'm not sure what the runout spec is on that honestly. Don't believe I've ever seen a number put to it but 2mm doesn't seem large enough that I'd be concerned.

also just a mention but the imbalance on the 302 changed after 1982, earlier ones will bolt up but they have the wrong weight and the engine will vibrate badly. There is also something about different tooth counts depending on the transmission or starter. Forget the fine points of that but I believe you would need an 83+ AOD-specific flex plate.

[Arquemann]

I have ogled at every moving component in the engine, I can't see any cracks in the pistons atleast without removing them from the bores, I can't make the wrist pins make any noise by hand and the rest of the moving parts are sitting on a table.
I can't find anything wrong. I ordered new seals and gaskets and I just gotta put it back together I guess. Hard part will be putting the crank back with 8 rods in the way.

Also the flexplate that was dimensionally the same, is actually a bit lighter. 163 teef

[gadget73]

so i was wrong about ring gear runout. Its 0.060 inches.

[DerekTheGreat]

Man, you are thorough. "..he's a good man, and thorough."

"Teef" - LoL

Sidenote: Yay, this website isn't displaying funny any more and I can post again! (Not sure what settings I need to change to make this permanent, comes and goes..)

[Arquemann]

Bottom end is back together, torqued, lubed and spins nicely. Also plopped in the oil pump as I had a spare gasket. Timing set and valvetrain assembly left before I need new gaskets, which should come this week, hopefully. Among the gaskets is an intake kit for an exploder, I'm trying out the rubber china wall gaskets. Out of principle I want to assemble this engine without RTV, as an experiment. Only use gaskets, seals and Permatex nr3.

Man, you are thorough

Well yes, I'm too broke to fuck things up out of carelessness (or any other reason tbh), so I'd certainly like to not waste a bunch of money if I can prevent it. I'm not a halfass kinda guy in any situation. Rather do a health checkup than an autopsy. And I'm not exactly happy that my gasoline V8 sounds like a diesel V8, any implied issues included, its embarrassing.