304 Flywheel

[mriplaybass]

As many of you know, we have been doing a major renovation on our 79 CJ7 . When we bought it, it had a T-18 from a 78 J series truck complete with long input shaft and about a 4 1/2" to 5" adapter. We picked up a short shaft T-18 last fall, and decided to make the switch since the whole drive line is out of the Jeep right now. I have finished the engine rebuild, and installed the engine a few days ago. Today, I thought that before I put everything back on the front of the engine, I would hook up the starter and make sure that the engine starts. With the battery sitting on the front fender, and a push button starter hooked up the solenoid, I poured a small amount of gas down the carburetor. I turned the key to run and hit the button. The engine fired immediately. I repeated this again, and the engine fired again. I figured that one more priming and the fuel pump should have filled the carburetor. When I hit the button this time, the starter made a loud grinding sound and the engine did not turn. I hit the button again, and I could see the wires to the starter jump from the heavy current draw, and the starter looked as if it was a little loose. Checked the bolts, and they were tight. Rather than risk damage, I pulled the starter. The bendix drive gear had split in half! First thing that I checked was to see if the engine had seized, it turned easily.
Here are a few questions that I have to help me evaluate my own hypothesis.
The numbers on this flywheel indicate that it came from a 1970s AMC 390
The clutch that was in it with the J truck Transmission was an 11" but the 10.5" clutch for the CJ7 bolted right up.
The bell housing that I put on is supposed to be from a CJ7 . The T-18 fits, and it bolts right up to the engine.
I am wondering about flywheel differences, bell housing differences, and anything else that could cause an improper mating of the starter and the flywheel ring gear.
When I look up ring gears for different Jeep trucks and CJ's, all the V8's use the same ring gear, and are therefore the same diameter.
Is it possible that I was sold a bell housing for a AMC 258 i6 / 4.2l ? Is there even a difference?
Do I need a flywheel shim?
I hate to give up and put the long shaft Transmission back in, but it's time to get things buttoned up and start enjoying some wheeling!
I have a few pictures showing the starter bore, the bottom of the bell housing, and the side of the bell housing.
There is only about 1/8" clearance between the ring gear and the bottom of the bell housing.
Maybe it's as simple as a bad starter, but I hate to buy a new one and destroy it the first time I try to start the engine.

 

[Torxhead]

You might want to take some measurements here Bass. Like put some blueing on the ring gear to check the mesh from the starter gear. It does sound like you might have a conglomeration of parts here, but it all seems to fit together. It just might be a bad starter here, as it did sound good on the first two fire ups. Do some checking for previous cracks on that break.

 

[mriplaybass]

Thanks Torx, The more that I think about it, the more I am beginning to think that it's the starter. As I said, I was using a starter button connected to the solenoid so that I could stand next to the carburetor while cranking. The last time that I primed it, I thought that the engine was about to quit, and I may have prematurely hit the starter button again. I know that when you engage a starter while the engine is still running, the drive gear should be able to kind of free wheel since the drive gear is kind of like a one way ratchet. Upon further investigation, I found that the drive gear does lock up the way it is supposed to while starting, but when I turned it the other direction, which should be the "free wheeling" direction, it turned hard and I could hear the bearing inside of it grinding.
I found out that all the AMC V8's in the late 70's all use the same flywheel ring gear thereby answering my question of different flywheel sizes. They are all the same OD.
I talked with Parts Mike about getting a different bell housing, and found out that the I6 and the V8's use the same bell housing.
I have the spacer between the engine and bell housing. Basically, everything is as it should be. So, I guess a new starter is the only logical thing left. Unfortunately, the broken half of the gear is on the wrong side of the flywheel, so I will have to take the Transmission out to get at it!

 

[Posi]

Sorry I got to this late.
Engine, flywheel, and clutch combination previously worked as it should so no problem with fitment there. You added an amc bell that works with the 6 or 8.
This leave the starter as the problem.

I would try loosening the bell bolts to see if you can fish out the piece without pulling the Transmission .

 

[mriplaybass]

Thanks Posi,
I plan on picking up a starter today. I haven't posted the rest of the story though.
When I put the clutch in last week, I made a discovery. The kit had a throw out bearing from a J truck, and even though I have a clutch fork from a J truck, the bearing ID's are different . I called Rock Auto and told them what had happened. Then the fun began. First, I filled out the "missing or wrong parts" form on their web site, and requested a correct bearing be sent. The reply was that I supposedly said that I got what was in the picture on their web site, and as such, the mistake was mine . I contacted them again and told them that is not what I said. I did not get what was pictured, and I sent them pictures. They agreed with me, and sent me a return shipping label to return the entire kit . I contacted them again and told them that I had already installed everything, and was not going to take it all apart again. They told me that they would call the manufacturer on Monday and see what they could do for me. I don't think the manufacturer was willing to send just the bearing, but Rock Auto contacted me and told me that they had the correct bearing, and would be shipping it out to me .
Still needing to build a crossmember for the new Transmission , and getting impatient to get the project moving again, I just installed the Transmission and Transfer Case so that I could measure things up. Long story short, the Transmission has to come back out anyway when the new throw out bearing arrives. I will remove the broken gear then.

 

[Posi]

Sorry to hear. At least with the Transmission out you will be able to easily do a full inspection of the ring gear teeth.