Flywheel bolt stripped

[Cooper]

I am replacing the AMC 304 in my CJ7 with a used 360. The 360 came from a Cherokee with an automatic Transmission , so had to change the flywheel. I used the flywheel bolts that came out of the AMC 304 (might have been a mistake). The book said to torque them to 105 ft. lbs. The first one went fine, but the next one stripped out the threads in the crankshaft. Is there a good way to fix this without replacing the crankshaft? Can I drill the holes out and put larger bolts in? Other suggestions?

 

[IOPort51]

I guess you could do a Helicoil but I don't think you will be doing 105 Ft/lb

I think I would run a bottoming tap through the rest to see if anything had been cross threaded some in the long ago.

Actually I would tear the engine down and have the crank assembly ballanced with the flywheel. they are supposed to be a matched set. I can see it running a little rough when you are through.

I am replacing the AMC 304 in my CJ7 with a used 360. The 360 came from a Cherokee with an automatic Transmission , so had to change the flywheel. I used the flywheel bolts that came out of the AMC 304 (might have been a mistake). The book said to torque them to 105 ft. lbs. The first one went fine, but the next one stripped out the threads in the crankshaft. Is there a good way to fix this without replacing the crankshaft? Can I drill the holes out and put larger bolts in? Other suggestions?

 

[73CJ]

Ditto on the "replace the crankshaft.

That things spinning at 5000 rpm and not balanced anymore by adding a bigger bolt (more weight). Maybe a Helicoil, but still should be rebalanced.

 

[yleefox]

I normally would not put my .02cents worth into this discussion, but in this case I can not help myself. Regardless of what it take to properly resolve this issue, keep in mind that a flywheel that explodes or comes off can cause serious injury or death, not to mention the damage to the vehicle. I do not jest here, I have seen the results and the results were spectacular.

Replace the crankshaft if you have to. Maybe you can get away with having all the holes enlarged and tapped. But do not take a chance, it is not worth the risk.

Good luck, I hope it works out well for you.

Y

 

[Cooper]

Okay. Thanks. I was hoping to not have to do all that, but better safe than sorry.

 

[CJ]

I would helicoil every hole but you should easily get away with one helicoil.

If you just one run one the weight should be no problem. The coil replaces the drilled out metal and weighs very close to the weight removed. Even if it weighs slightly more or less, there will be very little affect due to the weight change being so close to the center of the crank.

The fly wheel is your biggest problem. You need to find a 360 fly wheel or have the AMC 304 one balanced as a 360. What is the casting # on the flywheel?

Here is a good write up on the different flywheels.

http://www.trailhed.com/amc_flywheel.html

Information was taken from Trailhead.com: http://www.trailhed.com/amc_flywheel.html

AMC flywheel information

Year Engine Part#
77-79 FOUR 325-0437
67-71 SIX 317-2415
72-79 SIX 321-2623
67-69 290 317-9069
70-71 AMC 304 319-6927
72-78 AMC 304 w/3s 321-2651
79 AMC 304 323-3955
67-69 343 318-1609
70-71 360 319-6929
72-74 360 321-2653
68-69 390 319-1662
70 390 319-6929
71 401 321-0496
72-74 401 w/4s 321-2655

THREE distinctly different versions of the flywheel with part #3197219. If
you have one of these flywheels, and you want to follow along with the
description that follows, place your flywheel flat on the bench with the
casting number facing up and at 12:00. (like you're reading a clock)

Version #1: #3197219-C
Crankshaft flange recess measurement: 4.500"
Counterweight position: at 7:30
Known to be out of a dead stock 1970 390 4-speed car.

Version #2: #3197219-C
Crankshaft flange recess measurement: 4.500"
Counterweight position: at 4:30
Known to be out of a dead stock 1970 360 4-speed car.

Version #3: #3197219
Does not have the "-C" after the casting
number, but does have "E-25" (or other letter/number combo) cast in
just above the counterweight.
Crankshaft flange recess measurement: 4.650 (approx. 5/32" larger
than the above two versions)
Counterweight position: 9:30
Exact application: unknown. Believed to be out of a 72/up 360 or 401
(AMC 304 's do not have a counterweight)

All cast-in counterweights are one square inch, with the exception of
version #3 which is 1/4" shorter. (length 1", width 1", depth 3/4")



CONTRIBUTORS:
"For more info on this, or any other AMC related topic, give me a call. "The
Voice Of Experience" Tony Zamisch California Classic AMC, Inc.
Aerolite Mfg. Co. (619) 423-0364 AMX-perience / Trans-Am Javelin www.AMCWC.com"




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[yleefox]

As CJ mentioned, a Helicoil should make for a good repair.

Y

 

[dpuck]

I normally would not put my .02cents worth into this discussion, but in this case I can not help myself. Regardless of what it take to properly resolve this issue, keep in mind that a flywheel that explodes or comes off can cause serious injury or death, not to mention the damage to the vehicle. I do not jest here, I have seen the results and the results were spectacular.

Replace the crankshaft if you have to. Maybe you can get away with having all the holes enlarged and tapped. But do not take a chance, it is not worth the risk.

Good luck, I hope it works out well for you.

Y

Amen to that. I have seen first hand the damage done by a flywheel coming apart in my little brothers old truck my years ago.
Pealed the gas peddle back, breaking his ankle. A pie shaped piece was wedged in the heater box. and the ring gear was turned wrong side out. Tore a couple of ears off the Transmission and engine block. I don't think we found much of anything of the bell housing.

 

[yleefox]

Not to beat this up any more, but I've seen the aftermath of a few of them. The worse punched assorted sized holes through the body and floor of a 55 chevy and wrecked the dash. Windshield did not fair well either.

Y