Flywheel Problem

Today I was tightening the flywheel mounting bolts to the crank. One of them stripped the threads in the crank. The motor is a 258.
Can I helicoil the crank?

What are my options?


I wire wheeled the bolts and cleaned the bolts and crank threads with laquer thinner before installing the bolts.

 

I'm also curious. One of the six bolts in my flexplate seems like it may strip out the crank if I need to remove and retighten it. I'm using the 232, which is the previous generation of the 258.

 

I heli-coiled 2 of them on my V8 without a problem.

 

Someone correct me if I'm wrong, but I believe starting in 1971 the 232 is the same generation as the 258. The smaller displacement was achieved by using a shorter stroke on the 232. Bore is the same. In 1972 they changed the bolt pattern on the bell housing to match the AMC V8's. But that change applied to both the 232 and the 258.

By the way, your 232 is gorgeous.

 

How long are the bolts? I pulled a flywheel off a 304 in the junkyard, and the bolts had about 1/4" engagement in the crankshaft. If the threads are stripped the full depth of the hole, a helicoil is about your only choice.
-Donny

 

I have been reading information on inserts. Some people feel a Keensert is better for the application than a Helicoil. Maybe I am over thinking this. I am concerned about it being a through hole.
Any comments?

Even though 5 bolts torqued correctly, I have been looking into new flywheel bolts. 1/2-20 x 7/8" I found ARP #146-2801.

I'm also looking for new clutch pressure plate bolts. 3/8-16 x 7/8"

 

Agreed, looks nice!

Not to overload with irrelevant facts, but yes, Jeff's 232 is the same generation as the 258.

This engine was originally released as the 199 and 232 in the mid 60s. It's notable because it uses a "modern" cast iron crankshaft with 7 main bearings. Previous Nash/AMC 6s both flathead and OHV had four main bearings and a forged steel crank, which was usual for the day. When Kaiser Jeep discontinued the OHC 230 domestically, they needed a six they could offer in the J-truck and Wagoneer. They purchased 232s from AMC for this purpose. This 199/232 has a unique bell pattern, with the starter on the left (driver's side). I think the bell pattern is the same as the earlier 196 cid flathead/OHV six that the 199/232 replaced.

AMC also had the 250/287/327 V8 through 67ish. This too has a unique bell pattern, different from the sixes. AMC replaced these heavy gen-1 V8s with their new lightweight V8 in 290/343/390 displacements for 1968. These new V8s also came with a new bell pattern, which I call the unified AMC pattern for reasons to be explained.

In 1970, AMC raised the deck and stroked these V8s to 304/360/401 cid, and unified the inline sixes with this V8 bell pattern, also moving the starter to the passenger side. The new 232 replaced the 199, and the new 258 replaced the 232. The 232 was now a high-deck stroked 199 and the 258 a high-deck stroked 232. As mentioned, the 232 and 258 blocks are the same AFAIK, with crank, rods and pistons being the only difference.

I recall this happened at mid-70ish, and the '71 and '72 engines can have a different flywheel flange? Lots of mixed up stuff in these years. Can be trouble when mixing and matching components for this era.

 

Thanks for the complements, all, but what counts is how she runs! If things go well and the temperatures get down into the chilly 80s, I may find out before August is done!

I knew that they changed the block to a High Block at some point - which (from your notes) must have been 1970 or so. But I was under the belief (and now, clearly, I was wrong) that once they had the 258 parts designed and available, why bother shoving in 232 parts? It's the same block and head. Was there a true disadvantage to using the different crankshaft and connecting rods? I thought that I had a 232 because there was no 258 available back then. But it's the same block (duh!) so they *must* have had it, and I know that it's a 100% drop in replacement.

Ergo, the United States Postal Service was a bunch of cheap, tight @$$3d individuals for not springing for the bigger motor. A bigger motor that would only burn more fuel and not give any sort of performance boost for a vehicle that needed their brakes relined quarterly. Sigh.

Did they not know, in advance, that I'd want one of these, so it shoulda been tricked out? I'm not saying mag wheels or spoilers, but at least the bigger engine?

NOTE TO SELF: Instead of ever looking for a 232 to replace your over-bored unit, go straight to the 258 because the bolt pattern will always have to be correct.

 

In '74 the 232 is what you got when you bought the base model Gremlin or Hornet. The 258 option was not very much, like $25 or $50, but when you're a fleet buyer, those extra dollars add up. AMC had a reputation for making economical small cars with smooth, quiet sixes. Likely made economic sense to offer the smaller engine for their economy cars. Hardly ever saw one of these 232s in a Jeep, as I recall. Nothing wrong with this 232; 10% less displacement from a 258 should be about 10% less power, but still on a par with similar displacement engines of its era (cough cough ... 225 cough). Still quite an improvement from the F134. You can drive a 232 CJ on the freeway no problem.

 

I had a '74 CJ5 with the 232. It was gutless compared to a 258 in a friend's CJ5. Both had T14/ D20 behind them. I sold the engine many years ago as a replacement for a freeze-cracked block, but still have the trans/TC.
-Donny