2fe engine questions (1 Viewer)

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Jul 7, 2020
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Location
saint petersburg, Fl
2fe Engine Questions



I’ve really been starting to try and understand the engine lately as I am not very mechanically inclined, but I’d like for that to change and I figure there’s only one way of that to happen - research, questions, and more questions. I’ve started around the cylinders and I’ll keep trying to learn as much as I can. I’ve read some on mud, but I figure I’d check out some other, subject specific resources for newbies that are just starting. Here are some questions that arose from the following prompts. Please explain if you can, in as simple terms as possible because I am still very new to this. And please feel free to start explaining any other stuff you feel necessary because even if I don’t need it now, I’ll need it in the future. Thank you, and pardon my ignorance.


46190C39-3282-4775-A207-F9650D9F6C5E.jpeg

What does it mean when it says “increasing the engines crankshaft arm or lever”? Where is the crankshaft arm or lever?

E96422C0-89CA-4CBD-A09D-FF0950FD31D7.jpeg


Are the piston rings inside of the grooves towards the end of the piston?

A988266A-4247-4E04-977A-50381439224C.jpeg


Is this referring to what I’ve seen here on mud as not passing the emission tests? Why wouldn’t they pass the tests?


0F2692A0-7053-4381-A2B5-CF209289144C.jpeg

I really do not understand any of the process of engine balancing.


DF4979ED-DBCD-4364-9A79-4C2E56FFEE17.jpeg

What are the wrist pins, rings, and rod bolts talked about here? Also what exactly does good compression mean?



Also found this picture on a 2fe engine rebuild, I know that it’s the cylinder head, if someone could please explain a bit how this works in relation to the cylinders, and just in general. Thanks.
 

iptman

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Do you have Auto Shop class at your high school? If so, sign up. These are all general automotive questions you should ask someone paid to teach you. Or go to the library and check some books out. I'm sure there's an automotive section. For FJ40 specific knowledge start reading threads in the FAQ at the top of the main page. Lots of free information there.
 

1911

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What does it mean when it says “increasing the engines crankshaft arm or lever”? Where is the crankshaft arm or lever?

It is the distance between the offset (big-end) connecting rod journals and the crankshaft center line. The longer this distance is, the farther the pistons will travel up and down in the cylinder bore, the more volume they will displace, and the more leverage can applied to the crankshaft. There are trade-offs for doing this, the main one is that you will trade more torque for less top-end rpm (and hence top-end hp).

So, the 3F and 3FE engines are de-stroked from the 2F. They did this to get more rpm and top-end hp for a better highway engine, but the 2F generates more torque in a lower rpm band, so it is better for wheeling. The idea of a 2FE is to have the best of both worlds; the fuel injection and better flow characteristics of the 3FE head and manifolds with the longer stroke of the 2F.


Are the piston rings inside of the grooves towards the end of the piston?

Yes.


Is this referring to what I’ve seen here on mud as not passing the emission tests? Why wouldn’t they pass the tests?

Any number of reasons why a 40+ year-old truck would not pass emissions (if required), but a poor cylinder hone job would not usually be near the top of the list in my book.


I really do not understand any of the process of engine balancing.

There are two main ways to balance an engine: static and dynamic. Static balancing is easier and cheaper; dynamic takes more machinery, skill, time, and money to accomplish. Basically, there are two goals to balancing: 1) try to make the reciprocating mass of every cylinder as close as possible to equal to each other, and 2) make the entire reciprocating mass of the whole engine close to harmonically-balanced at a desirable (useful) rpm. The first one can be done to any engine without much trouble. The success of the second one depends very much on the design (geometry) of the engine layout and the inherent balance problems that come with that. Example: it is theoretically possible to have a 90-degree V motor in perfect primary balance, but when you vary the angle of the V to more or less than that you will introduce imbalance and vibrations at certain rpm's.

In a straight six engine like the F-series, primary balance is also theoretically perfect, because the firing intervals can be spaced equally along crankshaft rotation. The problem is though, that because it is a four-stroke engine, you will always have two pistons moving up and down exactly together, which creates a secondary imbalance. It is possible to partially counteract this secondary imbalance by having weights in various places on the crankshaft (which you see on the stock crankshaft). So, in the F engines, making the rotating mass of all cylinders as close as possible has a large benefit. Dynamic balancing of the entire engine rotating mass can fine-tune the factory-designed offset weights on the crankshaft.


What are the wrist pins, rings, and rod bolts talked about here?

Piston wrist pins (at the top-end of the connecting rod), piston rings in grooves in the pistons to control compression and blow-by, and the rod bolts are the bolts that hold the big-end (bottom end) of the connecting rod to the crankshaft journal.


Also what exactly does good compression mean?

Depends on the engine. The limits of acceptable compression (in psi) for the F motors are given in the factory service manual. The F-series are low-compression tractor motors, meant to be able to run any sh!tty gasoline the world over and be reliable. On a well-used F engine, anything over 100 psi per cylinder is generally accepted as decent compression, but these motors will run fine on less. More important is to have no large variations between the individual cylinders compression.


Also found this picture on a 2fe engine rebuild, I know that it’s the cylinder head, if someone could please explain a bit how this works in relation to the cylinders, and just in general. Thanks.

Google "four-stroke engine" and you will get explanations and diagrams showing how the head works with the rest of the engine block.

The F engines are overhead valve (but not overhead cam), flat-tappet engines, so the head holds the intake and exhaust valves, and the rocker arms and push rods that push the valves, but little else - some coolant and oil passages.
 
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It is the distance between the offset (big-end) connecting rod journals and the crankshaft center line. The longer this distance is, the farther the pistons will travel up and down in the cylinder bore, the more volume they will displace, and the more leverage can applied to the crankshaft. There are trade-offs for doing this, the main one is that you will trade more torque for less top-end rpm (and hence top-end hp).

So, the 3F and 3FE engines are de-stroked from the 2F. They did this to get more rpm and top-end hp for a better highway engine, but the 2F generates more torque in a lower rpm band, so it is better for wheeling. The idea of a 2FE is to have the best of both worlds; the fuel injection and better flow characteristics of the 3FE head and manifolds with the longer stroke of the 2F.

While this is a great description of how differences in stroke works. Actually modifying an existing crankshaft or creating a whole new crankshaft is way beyond the means of most of us. It is a very large, heavy and precise part that you don't just start welding on.

There are occasionally a crankshaft from one engine that can fit into another, i.e. putting a 2F crankshaft in a 3FE (though, I'm not positive that's possible) or whatever GM crank and block combo people have found to make a GM 383 V8. But this is really pretty rare. And requires making sure the piston rods are also appropriately shortened so the piston doesn't go up too high and hit the head. And that there's space inside the block for the larger crank to spin without hitting shtuff.

Also, about honing, piston rings and the piston wall are both metal in direct contact with each other, and in time with the engine running the pistons going up and down creates grooves in the cylinder walls. "Good compression" relies partially on not allowing air to escape from the cylinder between the piston and the cylinder wall which is "sealed" by the piston rings.

Honing basically removes these grooves and scratches up the cylinder walls so that new piston rings can create new grooves. And, if someone's describing how to "stroke" an engine in one paragraph and moving along to tell you honing is very advanced in the next, find a different book. Honing is really about the only part of machine work that I am comfortable doing in my own garage... unlike boring the cylinders or shaving the head, not only does honing not remove a lot of material but also does not have to result in something being near perfectly centered and perfectly round or perfectly flat.
 
Joined
Jul 7, 2020
Messages
78
Location
saint petersburg, Fl
It is the distance between the offset (big-end) connecting rod journals and the crankshaft center line. The longer this distance is, the farther the pistons will travel up and down in the cylinder bore, the more volume they will displace, and the more leverage can applied to the crankshaft. There are trade-offs for doing this, the main one is that you will trade more torque for less top-end rpm (and hence top-end hp).

So, the 3F and 3FE engines are de-stroked from the 2F. They did this to get more rpm and top-end hp for a better highway engine, but the 2F generates more torque in a lower rpm band, so it is better for wheeling. The idea of a 2FE is to have the best of both worlds; the fuel injection and better flow characteristics of the 3FE head and manifolds with the longer stroke of the 2F.




Yes.




Any number of reasons why a 40+ year-old truck would not pass emissions (if required), but a poor cylinder hone job would not usually be near the top of the list in my book.




There are two main ways to balance an engine: static and dynamic. Static balancing is easier and cheaper; dynamic takes more machinery, skill, time, and money to accomplish. Basically, there are two goals to balancing: 1) try to make the reciprocating mass of every cylinder as close as possible to equal to each other, and 2) make the entire reciprocating mass of the whole engine close to harmonically-balanced at a desirable (useful) rpm. The first one can be done to any engine without much trouble. The success of the second one depends very much on the design (geometry) of the engine layout and the inherent balance problems that come with that. Example: it is theoretically possible to have a 90-degree V motor in perfect primary balance, but when you vary the angle of the V to more or less than that you will introduce imbalance and vibrations at certain rpm's.

In a straight six engine like the F-series, primary balance is also theoretically perfect, because the firing intervals can be spaced equally along crankshaft rotation. The problem is though, that because it is a four-stroke engine, you will always have two pistons moving up and down exactly together, which creates a secondary imbalance. It is possible to partially counteract this secondary imbalance by having weights in various places on the crankshaft (which you see on the stock crankshaft). So, in the F engines, making the rotating mass of all cylinders as close as possible has a large benefit. Dynamic balancing of the entire engine rotating mass can fine-tune the factory-designed offset weights on the crankshaft.




Piston wrist pins (at the top-end of the connecting rod), piston rings in grooves in the pistons to control compression and blow-by, and the rod bolts are the bolts that hold the big-end (bottom end) of the connecting rod to the crankshaft journal.




Depends on the engine. The limits of acceptable compression (in psi) for the F motors are given in the factory service manual. The F-series are low-compression tractor motors, meant to be able to run any sh!tty gasoline the world over and be reliable. On a well-used F engine, anything over 100 psi per cylinder is generally accepted as decent compression, but these motors will run fine on less. More important is to have no large variations between the individual cylinders compression.




Google "four-stroke engine" and you will get explanations and diagrams showing how the head works with the rest of the engine block.

The F engines are overhead valve (but not overhead cam), flat-tappet engines, so the head holds the intake and exhaust valves, and the rocker arms and push rods that push the valves, but little else - some coolant and oil passages.
Some of these YouTube vids might help ya. "Click Here"
While this is a great description of how differences in stroke works. Actually modifying an existing crankshaft or creating a whole new crankshaft is way beyond the means of most of us. It is a very large, heavy and precise part that you don't just start welding on.

There are occasionally a crankshaft from one engine that can fit into another, i.e. putting a 2F crankshaft in a 3FE (though, I'm not positive that's possible) or whatever GM crank and block combo people have found to make a GM 383 V8. But this is really pretty rare. And requires making sure the piston rods are also appropriately shortened so the piston doesn't go up too high and hit the head. And that there's space inside the block for the larger crank to spin without hitting shtuff.

Also, about honing, piston rings and the piston wall are both metal in direct contact with each other, and in time with the engine running the pistons going up and down creates grooves in the cylinder walls. "Good compression" relies partially on not allowing air to escape from the cylinder between the piston and the cylinder wall which is "sealed" by the piston rings.

Honing basically removes these grooves and scratches up the cylinder walls so that new piston rings can create new grooves. And, if someone's describing how to "stroke" an engine in one paragraph and moving along to tell you honing is very advanced in the next, find a different book. Honing is really about the only part of machine work that I am comfortable doing in my own garage... unlike boring the cylinders or shaving the head, not only does honing not remove a lot of material but also does not have to result in something being near perfectly centered and perfectly round or perfectly flat.

Thanj you everyone!! I’ve taken my time on contemplating this, researching,watching videos, and overall learning. I appreciate everyone’s input!
 

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