AMC’s (American Motors) Little Mistake: How AMC Created Issues for Its Engines

Added: 2026-05-12

[00:00:04]In the grand scheme of things, it's hard to believe that American Motors did so much with so little. The company was highly innovative for many years despite the fact that it often had a very small amount of capital that could reinvest in the company for future product development. I think interestingly, the real nail in the coffin for AMC was the acquisition of Jeep in the early 1970s as the company had to take on a lot of debt in order to finance the acquisition which came with a significant amount of interest expense, effectively eating up a lot of the company's earnings in order to pay for the interest on the debt and eventually retire it.

[00:00:46]But perhaps another issue by this point was that AMC was trying to compete against the Big Three in almost every market, not just the compact car space like it had under George Romney.

[00:00:58]Nonetheless, little AMC continued to churn out many different and interesting products with, as I mentioned, a very limited budget. Now one of the things that AMC often did was really produce excellent vehicles from a reliability standpoint. One might fault the AMC build quality and the gaps in the fit and finish as being sub par.

[00:01:20]But in general, the cars that they produced were very reliable. AMC never made its own transmission, instead electing to source those, as an example, the automatics from BorgWarner early on or later from Chrysler in terms of the TorqueFlite. But AMC did make its own engines and made excellent ones at that.

[00:01:39]Its six-cylinder engines that came in various displacements, as well as its own V8 engine which came in displacements all the way up to 401 cubic inches were really just gems of engines that were highly reliable and really trouble-free. Perhaps another thing that made AMCs trouble-free was that they employed whatever components they want. AMC often, some people said, stood for all makes combined and I can certainly see that.

[00:02:04]Because they sourced components effectively from everywhere. Alternators from General Motors, electrical systems from Motorola or Ford in some years.

[00:02:16]Ignition systems from Ford, often times Motorcraft electronic ignition, Carter's Carter carburetors.

[00:02:24]Uh they really just used all different types of components for their vehicles and it worked.

[00:02:32]So AMC's were known, as I said, for often having not the best build quality, but being pretty tough little vehicles and very reliable cars that were tough to kill by anything other than rust. AMC was also innovative in offering the first factory Ziebart protection.

[00:02:49]That was a pretty decent program, but during this time AMC in the early 1980s was using all galvanized metal in its exterior body panels, so they often didn't rust, but they didn't use galvanized metal for the underbody, which would still rust out. Regardless, one of the things I wanted to talk about today was that AMC did have a goof, I think. And I call it a little goof because there was some innovation here that actually worked quite well. But there is one infamous component, if you are an AMC fan, that you have to acknowledge really didn't work.

[00:03:24]Now AMC was a pioneer in the use of a polymer called Kraton polymer and this was really a polymer that was able to be used in many different applications and they could be flexible or they could be more rigid. Now an application of the former was the filler panel on the 1974 AMC Matador in between the bumper and the body that was flexible and that enabled the car to have a good an appropriate 5-mph impact-related bumper and bumper system, which meant that if the car hit a barrier head-on at 5 mph, that the bumper would kind of give, and that Kraton plastic filler would also give along with it, and would enable no damage to occur in those low-speed impacts. This was something that the insurance industry lobbied for for years, and cars beginning with the 1973 model year had to adhere to such a standard in the front and the 1974 model year in the front and the rear. And AMC used this as a filler in order to kind of disguise that gap that was caused by the protrusion of the bumper from the body, as you can see on this Matador. Now, the 1974 Matador wasn't all that great of a looker, at least in terms of the four-door. And there was also the beautiful, I say beautiful a little bit tongue-in-cheek, Matador coupe as well. And I think that one looked a little bit better.

[00:04:59]Now, another application that employed Kraton was the fender flares on AMC Eagles. Now, as you may not know, the AMC Eagle was effectively an AMC Concord to which a Jeep transfer case, a single-speed transfer case, was effectively bolted up underneath and transformed the AMC Concord into a four-wheel drive vehicle, a highly innovative crossover from the time in which crossover, and that term, really was something that had not yet been invented. So, AMC created that, but in creating the Eagle, one of the things that it had was a higher ride height than the Concord in order to accommodate the four-wheel drive system.

[00:05:43]Now, in order to ensure that the car didn't look funny, designers kind of grafted on these fender flares to help give the car a little bit more of a hefty look.

[00:05:54]And in order to form them, AMC employed those Krayton polymers to create the fender flares. So, it's a very cost-effective style fender flare on the AMC Eagle. Interestingly, the Concord would employ Krayton as well for that filler panel in between the bumper and the body, as you can see here in this rear photo. But, the Eagle had the bumpers tighter to the body because it was classified as a truck versus a car. So, it didn't have to meet the 5 mph impact standard front and rear. So, it could have the bumpers closer to the body.

[00:06:31]So, in this case, the Krayton was actually a pretty good application and worked well for AMC. And I don't think anybody felt that it was an inadequate application. So, what is AMC's little goof when it comes to Krayton? Well, there was one application that didn't work out so well, and any AMC owner will know this.

[00:06:53]Under hood, and AMC employed Krayton for valve covers on its six-cylinder engines for a number of years. Now, the unfortunate part about the Krayton valve covers that AMC employed is that they would often warp, or they were easy to warp, particularly when over-tightening the fastening systems for those valve covers, and then they basically were just junk, unfortunately.

[00:07:22]And you had to tighten some of those fasteners for the valve cover to specs in inch-pounds. Yes, inch-pounds, not foot-pounds, inch-pounds. So, they really were not supposed to be tightened down very much at all. And back in this timeframe, some mechanics just didn't even buy torque wrenches that had inch-pound specs. They only had foot-pound specs.

[00:07:46]So, those would warp and then they would leak and then you just have oil dumping out all over the engine from the valve cover. It's one of the reasons why many AMC owners have converted the cars that have the Krayton valve covers to the old style metal ones or an aftermarket metal one in order to stop the perpetual leakage. So, this was an unfortunate application for Krayton and I don't know if some of the issue here was just the thermal cycling, the engine heating up and then cooling down, heating up and cooling down repeatedly coupled with probably mechanics not exactly knowing what they were doing or being equipped with the right tools, but unfortunately, this was a little goof I think that was employing that Krayton polymer under hood in this application because uh from what I can discern, it caused AMC a fair amount of warranty issues.

[00:08:40]And it just created a headache for an engine that really was pretty much trouble-free otherwise. The only thing I can say about my AMC Eagle with the uh 4.2 L 258 cubic inch inline six under hood is that it's extremely smooth and a very reliable powertrain. The Carter carburetor sometimes is a little bit temperamental, particularly the idle circuits. Uh these are cars that with the carburetor sometimes they like to uh after you start them and put them in gear stall out. But you could kind of get away without rebuilding the carburetor and just squirting some carburetor cleaner down the little idle passages that are in the throat of the carburetor and some of the uh jets and that often clears it out and then it no longer stalls and idles smoothly.

[00:09:30]But otherwise, the engine is very trouble-free except for this application that I said was unfortunate. Otherwise, AMC's were generally good and reliable and tough vehicles, just like my AMC Eagle. And they even came with cool interiors, like this kind of tartan interior that you can see on my AMC Eagle.

[00:09:51]Ooh, the seats are very comfortable, by the way, and were individually reclining, something that was still a rarity for other American automakers, for whatever reason, during this time.

[00:10:00]It took many American auto companies years to adopt individually reclining seats, but not AMC, perhaps because they always had the traveling salesman seat that could kind of the front seatback could made up with the rear seat to form a little bed in the back on many of the older AMC models, and maybe that's one of the reasons why they had the individual reclining seats sooner.

[00:10:22]So, what do you think of this little quirk? Put a comment in the comment section and let me know. Thanks again for watching.