Rusty_OToole

Well boys there you have it. 8 votes for DIY repair. I agree that Epoxy will do a better job than Bondo. Remember OP said this is for a driver 3/4 ton truck not a show car.

V out the cracks with a grinder, fill with Bondo sand smooth and paint the wheel. Cost you about $10 bucks.

So, you definitely have electronic ignition, appears to be Motorcraft brand which is made by Ford. Follow the wires from the distributor to the ignition module and see what kind it is. AMC changed suppliers around the time your car was made. Cap and rotor look like new should not need to be changed. I would put in a new set of spark plugs, and let it go at that. Unless you have reason to believe there is something wrong. If you want to spend a little money you could splurge on Bosch platinum spark plugs. Or, if you prefer, use the original equipment brand. In any case check the plug gap and adjust to factory spec if necessary. There is a simple test for worn spark plug wires. Go out at night and, with the engine idling, look for sparks jumping from the wires to ground. To make the test extra hard you can mist some water from a spray bottle on them. If you see sparks the wires are bad and need to be replaced. With electronic ignition the timing does not change, unlike points ignition where it changes as the points wear and needs to be reset if the points are changed. You can check the timing with a timing light but it is probably ok.

The newer car - the one on the right - appears to be about a 1942 model. Postwar cars had similar body shapes but the front fenders were longer. On second thought, it could also be a 1946 47 or 48, it is hard to tell from this angle. It looks like a General Motors product but which one I could not say. Truck on the far right looks like a 1951 Ford.

Those analysers or dwell meters became obsolete when electronic ignition came in. No points to set, no dwell. You may find a use for a timing light and a multimeter. Even a vacuum gauge. But the dwell meter is not needed for your car.

If your car has electronic ignition - which I think everyone had by 1976 - there won't be any points or condenser to replace. And you don't replace the cap or plug wires unless they are worn out. Which they may be by now, on the other hand, they may have been replaced or may still be good. Is there any chance of getting an experienced mechanic to help out? I suspect this is the first time you tried anything like this? Later... did a little checking, apparently they used a Prestolite electronic ignition in 1976. From 1977 on they used a Motorcraft distributor. You might find some better information here, on the AMC bulletin board https://theamcforum.com/forum/forums.html?SID=929-37b761f7874fc9532z25757662037

If I recall correctly a 76 AMC should have an Autolite electronic ignition like a Ford. In any case you should get a repair manual, it will save you time and money.

The drawing shows a cross section through the cylinder block and head of a typical side valve engine in which the valves lie side by side in the Cylinder block. The plan view shows the combustion chamber relative to the cylinder bore, please note the small gap between the combustion chamber and the cylinder bore as this is the basis for the invention. In the opening paragraphs of Ricardo`s specification he describes all the problems which plague this type of side valve engine, the main one being the lack of turbulence in the head. Another problem he outlines is “that increase of the compression beyond a certain and fairly low figure merely results in a greatly increased tendency to detonation without affecting any appreciable improvement in either the power output or economy”. The text then goes on to explain that “all things being equal” an overhead valve engine with a symmetrical cylinder head will give 10% to 20% improvement in power output over the side valve arrangement. Having set down the disadvantages of the side valve layout, Ricardo then goes on to outline the basis of his invention. The cylinder head would be flat with a minimum clearance between it and the piston, the combustion chamber would be formed over the valves and connected to the cylinder by a small passage created by overlapping the combustion chamber with the cylinder bore, the passage having the same area as the inlet valve port Ricardo argues that this layout will create turbulence in the combustion chamber and with the sparking plug placed centrally in the combustion chamber will give conditions for greater power and economy and will permit a much higher compression ratio to be used without a tendency to detonation. You can see from the drawings that this design reduces the combustion chamber by half from the wide open design previously used. That when the piston comes up it will squirt the mixture towards the spark plug, causing turbulence which makes it burn quicker. And you can see why you can only make the combustion chamber so small before you cut off breathing.

To increase the compression you have to make the combustion chamber in the head smaller. But if you do this you cut off the air passage between the valves and cylinder. So the engine can't breathe. You can get up to 7.5:1 or maybe 8:1 compression, depending on engine design, but that is about the limit. Now about supercharging. With a normally aspirated engine you depend on atmospheric pressure to fill the cylinder. This is 14.7 pounds per square inch at sea level. Less at higher altitudes. So let's say you have 14 PSI filling your cylinders. Now you add a blower that gives it another 7 PSI. It stands to reason that you will force 50% more air into the cylinders since 7 is 50% of 14. I hope this is clear. Now let's say each cylinder holds 36 cubic inches and you have a 6:1 compression ratio. That means the combustion chamber must be 6 cubic inches. Now if you over fill the cylinders by 50% to 54 cu in and compress that into the same combustion chamber you will have the equivalent of 9:1 compression. There is a rule of thumb that your octane should look like your compression ratio. A 6:1 compression motor will run fine on 60 octane gas. But a 9:1 compression motor needs 90 octane gas. This is not a hard and fast rule just a guide. But you see where I am going with this.

For various technical reasons flatheads respond very well to supercharging especially centrifugal superchargers and turbochargers. We have already covered the fact that they have low compression ratios. This is an advantage for supercharging. Suppose you add 7 pounds of boost, this will increase cylinder filling by 50% which means your 6:1 compression becomes 9:1 which is about what you want to run on pump premium. Flatheads are tuned for best cylinder filling and power at low to medium RPMs and run out of breath at high RPMs. Centrifugal superchargers mate well with this as they add little boost at low RPMs and more at higher RPMs. In the thirties you had centrifugal supercharged sixes with the same HP as a straight eight, and supercharged eights with the same HP as a V12. In the early fifties the flathead six Kaiser with supercharger had the same HP as a typical small block V8. Later the supercharged Studebaker 289 had the same HP as a 352 Packard. There has been some discussion of this on the HAMB bulletin board. A couple of guys have tried centrifugal superchargers on old Ford flathead 4 cylinder engines. They were impressed with the results. With no changes other than the supercharger they got much higher speeds, in fact they did not seem to have a top speed, they just kept slowly gaining speed until they ran out of room. This was in the beach races on sand that they call the race of gentlemen.

Just looking at improved port flow. You can have as large and well shaped intake and exhaust ports on a flathead as on an OHV engine, right up to the valve seats. The flathead can have larger valves than an OHV because the valve chamber can be wider than the cylinder bore. In the days of the small bore long stroke engine this was significant. Where the flathead loses is the 180 degree turn from the valve seat down into the cylinder. To have enough room for gases to flow you can't bring the head down too low or make the combustion chamber too small. This is not a big deal if you are aiming for a CR of less than 8:1. So the flathead had the advantage of large valves and the disadvantage of a sharp turn between the valve and cylinder. The OHV had the advantage of straight gas flow but the disadvantage of smaller valves. This of course was before the short stroke big bore era. In terms of power and efficiency it was a tossup for ordinary road use as long as fuel was no better than 70 or 75 octane. As soon as high octane leaded gas became available, along with short stroke big bore high compression OHV engines, the flathead became obsolete.

Joe we both know there was a lot more to the changeover to OHV engines in the early fifties. There was the chance to go to higher compression than was possible with a flathead because of the better high octane leaded gas. There was also the change to a short stroke big bore configuration from the previously fashionable long stroke designs. Then there was the fact that most of the new engines were V8s which have a very short, stiff crankshaft compared to a straight eight. All these factors, and a few others, went together to make a more powerful, low friction, high revving engine that could exceed the typical flathead in power and economy. Combine this with new automatic transmissions which encouraged even higher compression and hotter cams. So yes, there was a revolution in design and the flatheads did become "old hat". But I believe this has been exaggerated. A good flathead is far from the useless junk a lot of people think it is. And, in the period of 1922 to 1949 the flathead often had the advantage.

If you want to compare flathead to OHV engines in the twenties there was a dandy contest in 1927 to determine the stock car champion at Daytona Beach. The main contenders were the Auburn and Stutz speedsters. Both had straight eight engines of identical bore and stroke but the Auburn had a conventional Lycoming flathead while the Stutz had a very sophisticated overhead cam engine. The Auburn produced 88 HP while the Stutz made 115 HP. In the event they were very close within a couple of MPH of each other but the Stutz pulled off a win. The more powerful Stutz also weighed 700 pounds more than the Auburn. It had a heavier more powerful engine, a heavier drive train and heavier chassis. It also cost twice as much as an Auburn. Given the fact that the two were so close in size and performance, the Auburn for half the money seems like a bargain. 2 years later Auburn brought out an improved engine with 115HP. This was an extreme contrast between the most technically advanced overhead cam engine in America and the most basic flathead. Yet speed and performance were close. The typical pushrod OHV engine would not have done as well as the Stutz. For the ordinary motorist the flathead engine was the best choice.

If you read my post you would know that before the Ricardo head came out, OHV engines did have the advantage over the flathead in power. You car comparing 1923 engines. The Ricardo head came out in 1922. If the Studebaker was an older design it would explain the difference. References I find online say the 1923 Studebaker was a 40HP car and the1927 Buick 60HP. But the difference in year is significant. If you compared both from the same year you would not see such a big difference. I could throw in the 1924 Chrysler flathead six of 201 cubic inches, one of the first "high compression" motors at 68 HP. You notice this outdoes the Buick even though it is slightly smaller and a flathead. This illustrates my point that before 1922 the OHV engine had an advantage in power but with the new head design the advantage largely disappeared.

For an interesting comparison of flathead vs ohv let's look at 2 brand new V8 engines for 1949. Everyone remembers the Cadillac but Lincoln also had a brand new V8 that year, a flathead. Both made by experienced makers of luxury cars, using the state of the art engineering and manufacturing of the time. Both all new V8s Cadillac 331 cu in Lincoln 337 cu in Cadillac 160HP Lincoln 155HP Both had 7.5:1 compression ratio. As you can see there was not much to choose between them. Caddy had a trifle more HP but was it worth the extra cost and complexity? This comparison only lasted a short time. In a few years the Cadillac was improved with higher compression, hotter cams, more carburetors and got up to 230HP in the Eldorado version. Meanwhile Lincoln quietly dropped the flathead after 1951 and replaced it with their own OHV V8. The lesson is, as long as compression ratios stayed below 8:1 and fuel was no better than 70 or 75 octane there was not much point to an OHV engine. If you go back to the thirties and forties and compare HP per cubic inch of Buick and Chevrolet OHV engines to their flathead competitors you will wonder why they bothered to make an OHV engine.

If you find it easy to lift the head off a straight eight Buick you are a better man than I am. Back in the day you could get the auto machinist to come to you to grind valves, true cylinders and grind crank throws. Today you would probably have to tow the car to his shop if you could get it done at all.

We could add to the list, Plymouth and Dodge to 1959, some Dodge trucks to 1962, Rambler to 1964. Not sure when Hudson made their last flathead but believe you could still get one in 1956. Studebaker's small Champion six was only 170 cu in and 85HP later raised to 185 cu in. Rather underpowered. The bigger Commander six at 226 or 245 cu in would give more power. Don't be afraid of a flathead because it is a flathead. They are much easier to work on than more modern engines. I would be concerned about the parts supply. Any Chrysler product six cylinder is very easy and cheap to get parts for. The straight eights, not so much. Flathead Fords are well supported but good blocks without cracks are getting hard to find. Packards seem to be ok except for some prewar senior straight eight and V12 engines which are something of a nightmare to work on. Studebaker, Nash, Hudson,Olds, Pontiac, etc I'm not so sure, you could look into the parts situation before you buy one, possibly by contacting the owner's club.

In the early days meaning before 1920 there were a variety of engine designs tried. Flathead, T head, and OHV engines were popular. Duesenberg made an excellent engine with the valves at 90 degrees to the cylinders called a Walking Beam engine. Flatheads were popular because they were simple, quiet, cheap to build, easy to repair, and if you broke a valve spring (which was a common thing at the time) it did no harm as the valve could not crash into the piston. But the OHV engines, while more expensive, complex and noisier had a slight advantage in efficiency. Then came a major breakthrough called the Ricardo cylinder head. Invention of an English inventor Harry Ricardo and brought to the market in 1922. It introduced the idea of squish or quench. This did 2 things, it reduced the effective size of the combustion chamber at TDC and it caused turbulence. This allowed higher compression and faster combustion. With the new high compression Ricardo design OHV engines had little or no advantage over a flathead. While the flathead still had all the advantages above. Plus, you could use bigger valves in a flathead. With the valve chamber beside the cylinder, it could be wider than the cylinder, while OHV engines were restricted to the diameter of the cylinder. This was an important point with the small bore, long stroke engines then in vogue. So, from 1922 on, the flathead held all the cards. This is why there were practically no new OHV engines from then on, with the exception of a few old line companies that were committed to the OHV principle, and some all out racing engines with hemi heads, that would do anything to eke out a few more Horsepower. This was the rule until the early fifties. There were several technical developments that led to the use of OHV engines, the biggest one being the use of high octane leaded gas. Top compression ratio for a flathead is about 7.5 or 8:1. The highest I know of is 8.2:1 in a 1954 Packard straight eight, and they had to pull every trick in the book to get it that high. If you raise the compression beyond a certain point you cut off the breathing. This is not an issue with OHV engines. Now you know why the flathead was king from the early twenties to the early fifties, and why the OHV took over. There is still nothing wrong with a good flathead. They are smooth, reliable, quiet and a pleasure to drive as the long stroke and high torque make driving easy with almost no shifting required. And with low compression they run fine on the lowest octane regular, in fact, they run better on low octane fuel than high octane. If you want to go fast you need an OHV V8 but for driving pleasure a good flathead is hard to beat. By the way don't think all flatheads are deadheads on the road. The big Packard 400 straight eight could top 100MPH and was only a few tenths of a second behind its OHV competitors in acceleration.

flatHEAD six, flatHEAD six. Flat six engines are found in Porsches and Subarus not Graham Paiges.

Don't go by the sheet that comes with the carb kit. They are incomplete and filled with errors. Get the specs from a Plymouth repair manual, Carter repair manual, or MoToR Repair manual. Set it up exactly as specified and it should work perfect.

They were a continuation of the touring car which was the most common body style up to the mid 1920s. After that closed cars became common. I suppose there were a few old timers who preferred the open body style but by the late 30s they were very few, the last convertible sedans were 1939 models in most lines. Except for a couple of oddities like the Frazer (fake) convertible sedan/hardtop and the sixties Lincoln.

Some years ago I saw an article about the restoration of a 1937 Auto Union race car. The aluminum head needed repair, they consulted the experts at Reynolds Aluminum. They analysed the material and said, "this is the kind of metal we use for lamp posts and lawn furniture". In other words, the best aluminum available in 1937 was of very inferior quality compared to today's alloys. Then there is the fact that aluminum deteriorates or loses strength more than iron or steel. So, an old aluminum engine part is likely garage art unless it is an NOS never used piece. Even then it would be suspect. Have also heard that all Duesenbergs had aluminum connecting rods, and a true expert wouldn't even try to start an old engine until they had been replaced with new steel ones. They are too likely to fail due to age and metal fatigue.

The used car problem was something new in the twenties. For the first time there was a glut of used cars on the market. Ford's plan was to buy up old cars and melt them down for scrap, using the steel to make new Fords. A hundred years ago there was a lot of discussion in the industry about the used car problem and what could be done about it. That was Ford's solution.

Have you tried Egge Machine? They have been around since 1915, they may have made pistons for your car when it was new. https://egge.com/

Have you seen the retreaded tires on some big hiway trucks that are made by gluing a new tread onto an old carcase? The tread comes already vulcanized and molded with treads. I have thought you could retread a solid rubber tire by gluing on this kind of tread material.