[Kenth]

Originally Posted by TRADERMIKE 2012

The reason for this and other long posts that I have Posted is beneficial to me, so I don't have to be looking all over the forum for lots of posts and neither do my readers, I like to run my posts that way. You have the right to run your post any way you want. So, should I. There are others on this site with long posts, but you don't complain about them. Give me a break. In addition, if you look at the 37,784 hits that I have on this post alone, you would know why I am still here. See Mikes: "HO Information Divulged", it has 41,795 hits, last time I looked. Please don't leave, you can always skip over that which you don't want to read, at any time and your input is certainly necessary for the community, as well as me. Other people, all over the world are benefiting from the wisdom on these pages, I have had Moderators say that I present a lot of good info.

Your information about your car and engine is a prime example of what NOT to do and the good information comes from everyone who is trying to help you, don't believe otherwise, even if it seems like that information is not reaching you. I could be wrong, but the fact that people still look at your posts is just to see what craziness will come next. But as said, it's your car and you do what you want with it.

[TRADERMIKE 2012]

Originally Posted by Kenth

Looks like all but # 2 piston rods are mounted backwards with the pistons and oil spurt holes away from cam.
We all know, well almost all, what that means.
This engine is a true disaster and the owner is NOT making anything better...

BTW, there was nothing wrong with the flexplate, shim or reinforcement ring. And, ALL original Pontiac flexplate shims have 2 oval elongated holes.
Just torque it 95 lb/ft and it will NOT move (or make noises).

You said:


"Looks like all but # 2 piston rods are mounted backwards, with the pistons and oil spurt holes, away from the Cam. We all know, well almost all, what that means. This engine is a true disaster and the owner is "NOT" making anything better.

Mikes reply:

You can see that in the photos that I posted, my roommate felt, with his hands, each and every Rod and has determined that the Rods are orientated correctly. Flat to Flat and rounds to rounds?

[Holeshot71]

Originally Posted by Cliff R

No doubt a good bit of that RTV will end up in the oil pump tube pick up screen. I've pulled down PLENTY of engines assembled with
"generous" amounts of it and much like using teflon tape on fuel fittings that chit comes loose and "snakes" it way into everything.

It's been quite a few decades since I used factory cast iron rods but going from memory here the early rods that used oil spurt holes have the bearing tang on the same side and they face TOWARD THE CAMSHAFT.

Your pics, from what I can see of them having them facing AWAY FROM THE CAMSHAFT. IF I am correct everything involved with your spinning and rotating assembly is FUBAR!......

Someone please correct me if I'm wrong here as I don't have the energy to go to out to the shop and dig up a used Pontiac factory rod and not sure I have any made early enough to have spurt holes in them anyhow........

Just noticed this also, you are correct. Post 629 pic #4, rod is marked #6 or 8 but is definitely in hole #7 and is backwards.

[Stan Weiss]

Originally Posted by Stan Weiss

Yes the pistons were designed with a wrist pin offset and placed in the direction they were to quite the engine on cold start up. In the cases I have seen reversing the pistons at build time did no damage it just made the engine a little noisier. Remember almost all after market piston have no offset.

Stan

Originally Posted by PAUL K

Agree .... Only issues might be some noise and premature wear. What may cause an issue is if the rods were installed backwards along with the pistons. But if there is adequate rod side clearance that wouldn't matter either.

From Page #11 back in August

Stan

[Cliff R]

Copied from an older thread and contributed by GTO Freek, may be of interest to those that promote running stock type pistons with offset pins backwards:

"Here's another oft-misunderstood bit of techie trivia -- what is piston pin offset for? That is, what purpose does it serve? Let's examine that one.
Modern powersports engine pistons are not mounted on their connecting rods exactly on center. They are offset radially, that is, perpendicular to their rotational axis. In other words, in a vertical, single-cylinder engine, the piston is offset toward the exhaust side of the cylinder. That is, the piston pin hole is bored off center toward the intake side, usually less than 1 millimeter. It is frequently stated with a sort of bored complacency that the purpose of this offset is to reduce piston slap. The truth is, while piston slap is reduced through piston pin offset, but that is not the purpose of the technology.

The piston engine has three major parts: crankshaft, connecting rod, and piston. Each has a different job to do. The reciprocating part -- the piston -- makes the crankshaft -- the rotating part, uhh, rotate. The connecting rod is simply the part in the middle. It translates the piston's recip motion into the crankshaft rotary motion. The neat thing is that in the process, it shares in the motion of both. That is, the connecting rod is both a reciprocating part and a rotational part, at the same time. (In fact, when balancing an engine, it is common to divide the connecting rod's weight in two, thus permitting half its weight to be calculated as recip and half as rotation.) The point is, the upper half of the connecting rod reciprocates with the piston, the lower half rotates with the crankshaft, and this is important to understanding the stresses on all three parts, but especially those on the connecting rod.

The piston and its half of the connecting rod stops twice per crankshaft revolution, even though the crankshaft continues to turn. This means the piston and top of the rod also start back up twice. This stopping and starting imposes stresses on all three of the parts, stresses that increase with crankshaft rpm. To reduce these loads, the piston is mounted to the connecting rod slightly offset. This causes the piston to reach top dead center at a different time than the connecting rod, effectively spreading the shock loading over a greater number of crankshaft degrees. In short, the real reason for piston pin offset is that it softens reciprocal loading, permitting lighter more power-efficient parts to be used, and the engines to be capable of higher rpm.

However, there is another phenomenon at work also, a kind of side benefit. Because the connecting rod spends most of its time in the engine at an angle, the piston engine has what is called minor and major thrust. Major thrust refers to the downward-stroking piston's force against the cylinder wall during combustion, due to the rod being angled in that direction. Minor thrust is the piston's thrust against the opposite cylinder wall during compression, because the rod's angle is opposite also. These thrust forces push the piston firmly against the cylinder wall. The important thing is that at TDC, they flip-flop. Major thrust turns into minor thrust, and visa-versa. In older engines, this flip-flop caused the piston smack the cylinder, resulting in a noise. Fortunately, the piston pin offset in today's engines, besides reducing inertia stresses, does two things that reduce this noise. First, because the piston is mounted off center, the transition from major to minor thrust is less sudden. There is less impact. Second, instead of a sudden lateral shift, the piston actually rolls from major to minor thrust. That is, the piston shifts first at the skirt, then gradually the rest of the piston makes contact, instead of all of the piston at once.

To summarize, piston pin offset is the manufacturer's way of reducing stress on reciprocating parts. It permits these parts to be lighter, which results in more efficient manufacture and less power loss in the engine, as well as higher rpm. A complementary result of piston pin offset is reduced piston slap due to the more gradual shift from major to minor thrust. Make mine well done, please."

[Cliff R]

Just noticed this also, you are correct. Post 629 pic #4, rod is marked #6 or 8 but is definitely in hole #7 and is backwards.

"In other words and as I suspected the reciprocating/spinning assembly is FUBAR".........

[Holeshot71]

Quote:
Originally Posted by Stan Weiss View Post
Yes the pistons were designed with a wrist pin offset and placed in the direction they were to quite the engine on cold start up. In the cases I have seen reversing the pistons at build time did no damage it just made the engine a little noisier. Remember almost all after market piston have no offset.

Stan
Quote:
Originally Posted by PAUL K View Post
Agree .... Only issues might be some noise and premature wear. What may cause an issue is if the rods were installed backwards along with the pistons. But if there is adequate rod side clearance that wouldn't matter either.
From Page #11 back in August (Quote)

Suppose it wouldn’t hurt to go in there with some feeler gauges and check the side clearance? Looking at the pics more, there are definitely some rods that are correct and some that are not..

[Stan Weiss]

Originally Posted by Cliff R

Copied from an older thread and contributed by GTO Freek, may be of interest to those that promote running stock type pistons with offset pins backwards:

"Here's another oft-misunderstood bit of techie trivia -- what is piston pin offset for? That is, what purpose does it serve? Let's examine that one.
Modern powersports engine pistons are not mounted on their connecting rods exactly on center. They are offset radially, that is, perpendicular to their rotational axis. In other words, in a vertical, single-cylinder engine, the piston is offset toward the exhaust side of the cylinder. That is, the piston pin hole is bored off center toward the intake side, usually less than 1 millimeter. It is frequently stated with a sort of bored complacency that the purpose of this offset is to reduce piston slap. The truth is, while piston slap is reduced through piston pin offset, but that is not the purpose of the technology.

The piston engine has three major parts: crankshaft, connecting rod, and piston. Each has a different job to do. The reciprocating part -- the piston -- makes the crankshaft -- the rotating part, uhh, rotate. The connecting rod is simply the part in the middle. It translates the piston's recip motion into the crankshaft rotary motion. The neat thing is that in the process, it shares in the motion of both. That is, the connecting rod is both a reciprocating part and a rotational part, at the same time. (In fact, when balancing an engine, it is common to divide the connecting rod's weight in two, thus permitting half its weight to be calculated as recip and half as rotation.) The point is, the upper half of the connecting rod reciprocates with the piston, the lower half rotates with the crankshaft, and this is important to understanding the stresses on all three parts, but especially those on the connecting rod.

The piston and its half of the connecting rod stops twice per crankshaft revolution, even though the crankshaft continues to turn. This means the piston and top of the rod also start back up twice. This stopping and starting imposes stresses on all three of the parts, stresses that increase with crankshaft rpm. To reduce these loads, the piston is mounted to the connecting rod slightly offset. This causes the piston to reach top dead center at a different time than the connecting rod, effectively spreading the shock loading over a greater number of crankshaft degrees. In short, the real reason for piston pin offset is that it softens reciprocal loading, permitting lighter more power-efficient parts to be used, and the engines to be capable of higher rpm.

However, there is another phenomenon at work also, a kind of side benefit. Because the connecting rod spends most of its time in the engine at an angle, the piston engine has what is called minor and major thrust. Major thrust refers to the downward-stroking piston's force against the cylinder wall during combustion, due to the rod being angled in that direction. Minor thrust is the piston's thrust against the opposite cylinder wall during compression, because the rod's angle is opposite also. These thrust forces push the piston firmly against the cylinder wall. The important thing is that at TDC, they flip-flop. Major thrust turns into minor thrust, and visa-versa. In older engines, this flip-flop caused the piston smack the cylinder, resulting in a noise. Fortunately, the piston pin offset in today's engines, besides reducing inertia stresses, does two things that reduce this noise. First, because the piston is mounted off center, the transition from major to minor thrust is less sudden. There is less impact. Second, instead of a sudden lateral shift, the piston actually rolls from major to minor thrust. That is, the piston shifts first at the skirt, then gradually the rest of the piston makes contact, instead of all of the piston at once.

To summarize, piston pin offset is the manufacturer's way of reducing stress on reciprocating parts. It permits these parts to be lighter, which results in more efficient manufacture and less power loss in the engine, as well as higher rpm. A complementary result of piston pin offset is reduced piston slap due to the more gradual shift from major to minor thrust. Make mine well done, please."

Interesting read. 1 mm = 0.03937 inches. Pontiac offset is around 0.063 inches or over 50% greater.

Stan

[Cliff R]

One must NOT confuse running pistons with "no-offset" in either direction as being OK vs running factory pistons with offset in the wrong direction.

Since I appear to be the only dumb-ars that actually did this nearly 40 years ago and ended up with all sorts of issues plus had to remove the engine to put them in the right way, I'd say anyone who advocates running off-set pistons incorrectly in the block is just regurgitating old/outed and inaccurate information on the subject, or repeating a "wives tale"......IMHO.

Even if a few "racers" did this "back in the day" I'm sure they only did it because they didn't have the time, funds, parts availabilty or support to do it the right way with better parts designed and installed correctly.......FW that's worth....

If there is anything useful to take away from this WAY too long running thread, I'd advise anyone still following it to NEVER under any circumstances install pistons and or rods backwards in one of these engines. It's just not a good idea and you may be the next one on here with all sorts of issues and a thread running for nearly 650 responses and you are no closer to a good end result than when you started it.......

[Cliff R]

PS: In any case, before the mud starts slinging and stones start flying I'm exiting this thread stage left. I beleive now that we have found the problem and we already know the solution..........

[TRADERMIKE 2012]

Originally Posted by steve25

The last use of the oil spurt holes in the rods was in early 67 326 and 389 Motors.

The holes faced the center of the motor if the rods where oriented right .

Mikes reply:

I have presented a picture of the 428 ci motor with the Flats toward the Flats and the rounds facing the rounds, so how is it that the squirters determine the orientation of the Rods all of a sudden? I was told to check said info., now that I have done that, by hand feeling the rounds and flats. Will someone confirm, that at least, we don't have to worry about the Rods being in backwards. Only the Pistons, 7 of them, are now backwards, yes?

[Kenth]

Originally Posted by steve25

The last use of the oil spurt holes in the rods was in early 67 326 and 389 Motors.

WRONG!
1966 was the last year for 389.
Connecting rods with oil spurtholes was eliminated in September 1972.

FWIW

[TRADERMIKE 2012]

Originally Posted by Cliff R View Post
Copied from an older thread and contributed by GTO Freek, may be of interest to those that promote running stock type pistons with offset pins backwards:

"Here's another oft-misunderstood bit of techie trivia -- what is piston pin offset for? That is, what purpose does it serve? Let's examine that one.
Modern powersports engine pistons are not mounted on their connecting rods exactly on center. They are offset radially, that is, perpendicular to their rotational axis. In other words, in a vertical, single-cylinder engine, the piston is offset toward the exhaust side of the cylinder. That is, the piston pin hole is bored off center toward the intake side, usually less than 1 millimeter. It is frequently stated with a sort of bored complacency that the purpose of this offset is to reduce piston slap. The truth is, while piston slap is reduced through piston pin offset, but that is not the purpose of the technology.

The piston engine has three major parts: crankshaft, connecting rod, and piston. Each has a different job to do. The reciprocating part -- the piston -- makes the crankshaft -- the rotating part, uhh, rotate. The connecting rod is simply the part in the middle. It translates the piston's reciprocating motion into the crankshaft rotary motion. The neat thing is that in the process, it shares in the motion of both. That is, the connecting rod is both a reciprocating part and a rotational part, at the same time. (In fact, when balancing an engine, it is common to divide the connecting rod's weight in two, thus permitting half its weight to be calculated as reciprocating and half as rotation.) The point is, the upper half of the connecting rod reciprocates with the piston, the lower half rotates with the crankshaft, and this is important to understanding the stresses on all three parts, but especially those on the connecting rod.

The piston and its half of the connecting rod stops twice per crankshaft revolution, even though the crankshaft continues to turn. This means the piston and top of the rod also start back up twice. This stopping and starting imposes stresses on all three of the parts, stresses that increase with crankshaft rpm. To reduce these loads, the piston is mounted to the connecting rod slightly offset. This causes the piston to reach the top dead center at a different time than the connecting rod, effectively spreading the shock loading over a greater number of crankshaft degrees. In short, the real reason for piston pin offset is that it softens reciprocal loading, permitting lighter more power-efficient parts to be used, and the engines to be capable of higher rpm.

However, there is another phenomenon at work also, a kind of side benefit. Because the connecting rod spends most of its time in the engine at an angle, the piston engine has what is called minor and major thrust. Major thrust refers to the downward-stroking piston's force against the cylinder wall during combustion, due to the rod being angled in that direction. Minor thrust is the piston's thrust against the opposite cylinder wall during compression, because the rod's angle is opposite also. These thrust forces push the piston firmly against the cylinder wall. The important thing is that at TDC, they flip-flop. Major thrust turns into minor thrust, and vice versa. In older engines, this flip-flop caused the piston to smack the cylinder, resulting in a noise. Fortunately, the piston pin offset in today's engines, besides reducing inertia stresses, does two things that reduce this noise. First, because the piston is mounted off center, the transition from major to minor thrust is less sudden. There is less impact. Second, instead of a sudden lateral shift, the piston actually rolls from major to minor thrust. That is, the piston shifts first at the skirt, then gradually the rest of the piston makes contact, instead of all of the piston at once.

To summarize, piston pin offset is the manufacturer's way of reducing stress on reciprocating parts. It permits these parts to be lighter, which results in more efficient manufacture and less power loss in the engine, as well as higher rpm. A complementary result of piston pin offset is reduced piston slap due to the more gradual shift from major to minor thrust. Make mine well done, please."

Originally Posted by Stan Weiss

Interesting read. 1 mm = 0.03937 inches. Pontiac offset is around 0.063 inches or over 50% greater.

Stan

Thank you for that education, Mike replies...

[Kenth]

Originally Posted by TRADERMIKE 2012

Mikes reply:

I have presented a picture of the 428 ci motor with the Flats toward the Flats and the rounds facing the rounds, so how is it that the squirters determine the orientation of the Rods all of a sudden? I was told to check said info., now that I have done that, by hand feeling the rounds and flats. Will someone confirm, that at least, we don't have to worry about the Rods being in backwards. Only the Pistons, 7 of them, are now backwards, yes?

You are clearly in need of a Pontiac Service Manual.

HTH

[TRADERMIKE 2012]

Originally Posted by Kenth

WRONG!
1966 was the last year for 389.
Connecting rods with oil spurt holes was eliminated in September 1972.

FWIW

Does my 1967 428 ci motor have these squirt holes?

[TRADERMIKE 2012]

Originally Posted by Kenth

You are clearly in need of a Pontiac Service Manual.

HTH

Why evade the question, I went through all the work to check the lower end of this motor and the main reason was to see if the Rods were in correctly, but now you won't tell me. I ask not because I want to prove a point, I just want to know whether or not they are in backwards as the 7 pistons. There was great concern in the past posts. So, what is it?

NOTE: We felt, with our hands, that the flats were adjacent to each other in the center/center and that the rounds were adjacent to one another.

We deduce that the Rods are correctly orientated, thus only the 7 Pistons need to be re-orientated, this is a yes or no question please?

["QUICK-SILVER"]

Originally Posted by TRADERMIKE 2012

NOTE: We felt, with our hands, that the flats were adjacent to each other in the center/center and that the rounds were adjacent to one another.

We deduce that the Rods are correctly orientated, thus only the 7 Pistons need to be re-orientated, this is a yes or no question please?

Feeling with your hands would have took some mighty tiny fingers to slide in between rods bolted to the crank,

Squirt holes down are backwards rods.

Clay

[Kenth]

Originally Posted by TRADERMIKE 2012

Does my 1967 428 ci motor have these squirt holes?

It obviously have as you can see on your pictures, "only" problem they should aim towards camshaft and since they´re not the rods are mounted backword leaving less or no room for the rod bearing to the chamfer on crank resulting in glitter in oil, drag on crank and excessive heat building.

[TRADERMIKE 2012]

Originally Posted by Holeshot71

Quote:
Originally Posted by Stan Weiss View Post
Yes, the pistons were designed with a wrist pin offset and placed in the direction they were to quite the engine on cold start up. In the cases I have seen reversing the pistons at build time did no damage, it just made the engine a little noisier. Remember almost all after-market pistons have no offset.

Stan
Quote:
Originally Posted by PAUL K View Post
Agree .... The only issues might be some noise and premature wear. What may cause an issue is if the rods were installed backwards along with the pistons. But if there is adequate rod side clearance that wouldn't matter either.
From Page #11 back in August (Quote)

Suppose it wouldn’t hurt to go in there with some feeler gauges and check the side clearance? Looking at the pics more, there are definitely some rods that are correct and some that are not...

Mikes reply:

We already closed the bottom and building it as we speak, however if you look back in the posts in this thread you will find that we took these measurements.

Today we found that the Rods are in correctly.


"Why evade the question, I went through all the work to check the lower end of this motor and the main reason was to see if the Rods were in correctly, but now you won't tell me. I ask not because I want to prove a point, I just want to know whether or not they are in backwards as the 7 pistons. There was great concern in the past posts. So, what is it?

NOTE: We felt, with our hands, that the flats were adjacent to each other in the center/center and that the rounds were adjacent to one another.

We deduce that the Rods are correctly orientated, thus only the 7 Pistons need to be re-orientated, this is a yes or no question please?"

[462gto]

Below is a older thread on piston/rod orientation. Please look at the diagram on #32 of the link. Looking at your pictures it looks like some rods are numbered on the oil spurt hole side of the rod and others are solid side of the rod and maybe that's why the engine got assembled the way it is. You might want to verify that the correct numbered rods are in the cylinder that it should go in with the oil spurt holes (bearing tangs) oriented properly.

https://www.google.com/url?sa=t&sour...9pZW-iOF2D4Eos