Engine failure after 20000 km.

[Vicus]

So I guess you have ditched the 4 speed top loader idea then.

Not yet, Geoff, but I have to postpone the project until I'm allowed to retire. Then I will have more time at my disposal. It wasn't planned that the engine would break down before then, but as they say: things usually turn out differently thank you think.

 

[cjstaci]

50+ year old push rods could be a victim of metal fatigue, or excessive clearance due to a collapsed lifter or flattened cam lobe, loose or damaged rocker arm, weak or broken valve springs, any of which could be suspect.
Now is the time to bump your engine performance up, switch to closed chamber heads, hardened push rods. Guide plates and adjustable rockers. Probably aftermarket aluminum heads would be best for the money.
As long as everything is in good working order, you shouldn’t have any problem cruising on the autobahn at between 3000-5000 rpm. The drawback is of course more fuel consumption and more engine wear.
When I was in Germany, I had a Capri with a V4. I was driving from Kaiserslautern to Frankfort and running about 7000 rpm. That was about a 90-100 mph and people were passing me all the time. The pinion seal failed and fried the rear end. The car was towed to an impound lot. I had to come back, find a rear end in a salvage yard and then swap the rear end. Quite an ordeal.
I remember the speed limit in city areas was 100kph but unrestricted out of cities. If I were there, I would want the car to handle the autobahn speeds safely and easily.

 

[giantpune]

50+ year old push rods could be a victim of metal fatigue, or excessive clearance due to a collapsed lifter or flattened cam lobe, loose or damaged rocker arm, weak or broken valve springs, any of which could be suspect.
Now is the time to bump your engine performance up, switch to closed chamber heads, hardened push rods. Guide plates and adjustable rockers. Probably aftermarket aluminum heads would be best for the money.
As long as everything is in good working order, you shouldn’t have any problem cruising on the autobahn at between 3000-5000 rpm. The drawback is of course more fuel consumption and more engine wear.
When I was in Germany, I had a Capri with a V4. I was driving from Kaiserslautern to Frankfort and running about 7000 rpm. That was about a 90-100 mph and people were passing me all the time. The pinion seal failed and fried the rear end. The car was towed to an impound lot. I had to come back, find a rear end in a salvage yard and then swap the rear end. Quite an ordeal.
I remember the speed limit in city areas was 100kph but unrestricted out of cities. If I were there, I would want the car to handle the autobahn speeds safely and easily.

I think OP has discovered the downside to more engine wear. Things wear until they break.

 

[cjstaci]

I think OP has discovered the downside to more engine wear. Things wear until they break.

Wait a minute, you mean parts break when they wear out, that’s just crazy talk, lol.
I think ford should repair it under warranty, after all, it’s only been 50+ years.

 

[AcesArneson]

I should really think about an OD gearbox, whether AOD transmission or Gearvendors OD. However, the 2.75:1 rear axle reduces the revs by ~15% compared to the currently installed 3.25:1. That is immense.

Keep it as simple as you can. If you are looking for an easier time keeping up on the freeway then do an AOD or 4R70W swap. Lots of guys on this site (including myself) have done this. The end benefit is you have the same car with a bit more top speed that costs you less gas.
I don't subscribe to the 'you got to leave it as it is or it's not a classic' theory. If you want to restore your car to concours level then be my guest but if you just want to enjoy your classic, make it your own.

 

[Vicus]

Thank you all very much for your diverse opinions. Nobody expects everyone to have the same opinion.
First of all, I would like to mention that I am not part of the restomod movement. I chose a classic car, in this case a 72 Mach1, in its original state, because I like driving a car with this historic technology. I don't want to change it fundamentally, because I believe that the overall design and technique best reflects the technical achievements of the engineers of the time. On the other hand, the old technology also needs to come closer to today's habits.
For this, I prefer a well-maintained classic car that still works reliably today with the technology of the time.
I don't need a Coyote engine under the hood, digital instruments in the dashboard or 18" wheels in the wheel arches. Nor do I need a modern chassis or rack-and-pinion steering or an air-ride. My car brakes very reliably even with 4 drum brakes without a brake booster.
In return, I accept the installation of an electronic ignition system like the Pertronix, a home-made exhaust system with manifolds, and soon also aluminum heads. A Holley 4160 is already working reliably under the original air filter box. On the whole, my car will hardly show any change from the classic appearance on the outside, but it should work reliably. My car will spend most of its future automotive life on the back roads of its new home in southern Germany. The roads here are winding and it's more about torque than top speed. I try the 2.75:1 differential first, because it's already on the shelf and doesn't require any additional investment at the moment. 60 mph at less than 2500 rpm is much more pleasant, both for the engine and for my ears.
And if I do have to hit the highway, I just have to control myself and put my right foot less heavily on the gas pedal. At least from today's perspective, this seems feasible.

 

[Sheriff41]

Thank you all very much for your diverse opinions. Nobody expects everyone to have the same opinion.
First of all, I would like to mention that I am not part of the restomod movement. I chose a classic car, in this case a 72 Mach1, in its original state, because I like driving a car with this historic technology. I don't want to change it fundamentally, because I believe that the overall design and technique best reflects the technical achievements of the engineers of the time. On the other hand, the old technology also needs to come closer to today's habits.
For this, I prefer a well-maintained classic car that still works reliably today with the technology of the time.
I don't need a Coyote engine under the hood, digital instruments in the dashboard or 18" wheels in the wheel arches. Nor do I need a modern chassis or rack-and-pinion steering or an air-ride. My car brakes very reliably even with 4 drum brakes without a brake booster.
In return, I accept the installation of an electronic ignition system like the Pertronix, a home-made exhaust system with manifolds, and soon also aluminum heads. A Holley 4160 is already working reliably under the original air filter box. On the whole, my car will hardly show any change from the classic appearance on the outside, but it should work reliably. My car will spend most of its future automotive life on the back roads of its new home in southern Germany. The roads here are winding and it's more about torque than top speed. I try the 2.75:1 differential first, because it's already on the shelf and doesn't require any additional investment at the moment. 60 mph at less than 2500 rpm is much more pleasant, both for the engine and for my ears.
And if I do have to hit the highway, I just have to control myself and put my right foot less heavily on the gas pedal. At least from today's perspective, this seems feasible.

Can't argue with that. Driving a classic car in its as-designed configuration is a great way to appreciate our hobby. Best of luck on your rebuild and let us know how it goes!

 

[351c1971]

You might consider measuring the cam lift at the rocker arm of the valve with the failed pushrod. This will rule out any cam issues. The pushrod coming off the rocker could have caused the pushrod to be bent. Inspecting the lifter might also be a good idea.

 

[Vicus]

You might consider measuring the cam lift at the rocker arm of the valve with the failed pushrod. This will rule out any cam issues. The pushrod coming off the rocker could have caused the pushrod to be bent. Inspecting the lifter might also be a good idea.

When dismantling the engine and checking the removed parts, I noticed the following:
1. the hydraulic tappet of exhaust valve #2 has a burr on the camshaft side that can be clearly felt with the fingertip.
2. this hydraulic tappet was difficult to remove from its seat. It might be slightly deformed too.
3. the hydraulic tappet next to it could be removed without any play and also slipped back into its own seat and into that of the damaged hydraulic tappet.
4. the damaged hydraulic tappet could only have been forced into the other seat with force. I aborted the attempt.
5. exhaust valve #2 is straight, but: the upper tip is slightly thickened. It's only 0.020 inch, but I think it's caused by the damage.
6. overall it seems to me that the cause is the sunken exhaust valve. This changed the geometry and consequently the forces on the individual components. The weakest link, the original push rod, gave way in the end.
7. the camshaft has not yet been checked, but as the hydraulic tappet on the camshaft side is damaged, I assume that the camshaft is damaged. The risk is too great for me to continue using it, so I'm giving my engine a new camshaft.

 

[Vicus]

What leads me to believe that the sunken exhaust valve and the resulting change in the geometry of the valve train is the cause of the damage is the fact that exhaust valve #5 has also sunken. Not yet as deep as that of #2, but the push rod of #5 is also already slightly bent and is already rubbing against the cylinder head.

 

[giantpune]

7. the camshaft has not yet been checked, but as the hydraulic tappet on the camshaft side is damaged, I assume that the camshaft is damaged. The risk is too great for me to continue using it, so I'm giving my engine a new camshaft.

Based on the way you describe the lifter for #2, I agree. The lifter is trashed. That cam lobe is probably nuked even if you can't see it. Time for a new cam.

Since covid, the global supply for flat tappet cam cores and lifters seems to have gone downhill. The small percent of brand new aftermarket cams wiping out lobes is a lot higher than it ever was. I would say buy from a reputable brand. And then check your new lifters to see that they are domed before you install them.

 

[Vicus]

Based on the way you describe the lifter for #2, I agree. The lifter is trashed. That cam lobe is probably nuked even if you can't see it. Time for a new cam.

Since covid, the global supply for flat tappet cam cores and lifters seems to have gone downhill. The small percent of brand new aftermarket cams wiping out lobes is a lot higher than it ever was. I would say buy from a reputable brand. And then check your new lifters to see that they are domed before you install them.

Fortunately, I still have a Lunati flat tapped camshaft with hydraulic tappets and roller rocker arms on the shelf. The components will find their way into the engine.
I bought the Lunati kit before Covid. The saying that it's better to have than to need proves itself right again and again in our hobby.

 

[351c1971]

I am also concerned about the valve lash on the Sunken valve. With the cam on the base circle, a quick check on the hydraulic valve lash is to tighten the rocker to take up the lash until it just touches the pushrod then tighten it 3/4 to 1 turn. The rocker should be seated on the pedestal. You should be able to push the tip of the rocker up and down slightly, as the lifter plunger should be in the center of it’s travel.