Engine Rebuild Part 2
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Joined: Dec 2007
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From: Boise, Idaho
Yeah, that's what I'm thinking.
Hopefully it's just a matter of figuring out which ones have an offset which way, and rotating a few of them 180°. Fortunately, the dish is symmetrical, and not a D-shape.
Once I get this sorted out, do I want the offset toward the driver or passenger side?
Hopefully it's just a matter of figuring out which ones have an offset which way, and rotating a few of them 180°. Fortunately, the dish is symmetrical, and not a D-shape.
Once I get this sorted out, do I want the offset toward the driver or passenger side?
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From: Boise, Idaho
Okay, so, I think I have some good news.
I pulled out the two remaining pistons so I could see if there was an easy way to identify which side the pin was biased toward. After a closer look, it was pretty easy to tell. When looking at the backside of the top of the piston, there was an identifiable wide and narrow area in the recess.
Both of the extra pistons were biased toward the same side.
So, I flipped the engine over and examined the six pistons already in the engine and they were all biased toward the same side.
By the looks of it, in a 351w, all eight pistons are identical, as opposed to four to one side and four to the other. So, as such, all six pistons in my block are in line with each other with the pin offset toward the intake/passenger side of the block.
I'll still pass this by the builder, but I think all's well.
I pulled out the two remaining pistons so I could see if there was an easy way to identify which side the pin was biased toward. After a closer look, it was pretty easy to tell. When looking at the backside of the top of the piston, there was an identifiable wide and narrow area in the recess.
Both of the extra pistons were biased toward the same side.
So, I flipped the engine over and examined the six pistons already in the engine and they were all biased toward the same side.
By the looks of it, in a 351w, all eight pistons are identical, as opposed to four to one side and four to the other. So, as such, all six pistons in my block are in line with each other with the pin offset toward the intake/passenger side of the block.
I'll still pass this by the builder, but I think all's well.
Lead Driver
Joined: Mar 2008
Posts: 7,165
Likes: 375
From: Near Los Angeles
I'll bet you are soooo happy you found this before the install. Whew. I am on pins and needles, since I have the same pistons.
AB, could you pls explain once more, possibly in different terms, how you could see/tell which side the bias was on. I just didn't quite follow the first time you explained. Thx.
PS: Went back and re read FTF's post. Am I wrong, or does it seem the preload should be on the opposite side? I hope I am wrong.
FTF: Some engines have the pin offset by about .050" to make the engine a little quieter by putting a little preload on the thrust side of the piston to prevent piston slap on compression as the piston rocks across TDC. The preload on a six should be toward the left hand (drivers) side of the engine.
AB, could you pls explain once more, possibly in different terms, how you could see/tell which side the bias was on. I just didn't quite follow the first time you explained. Thx.
PS: Went back and re read FTF's post. Am I wrong, or does it seem the preload should be on the opposite side? I hope I am wrong.
FTF: Some engines have the pin offset by about .050" to make the engine a little quieter by putting a little preload on the thrust side of the piston to prevent piston slap on compression as the piston rocks across TDC. The preload on a six should be toward the left hand (drivers) side of the engine.
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From: Boise, Idaho
No worries, I had a feeling that wasn't going to be clear.
Those two spots right there. The one on the left is about finger width and the other on the right is about thumb width.
And yes, I'm very glad I discovered this before firing it up, before installing it, and before bolting the head down.
Those two spots right there. The one on the left is about finger width and the other on the right is about thumb width.
And yes, I'm very glad I discovered this before firing it up, before installing it, and before bolting the head down.
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From: Boise, Idaho
PS: Went back and re read FTF's post. Am I wrong, or does it seem the preload should be on the opposite side? I hope I am wrong.
FTF: Some engines have the pin offset by about .050" to make the engine a little quieter by putting a little preload on the thrust side of the piston to prevent piston slap on compression as the piston rocks across TDC. The preload on a six should be toward the left hand (drivers) side of the engine.
FTF: Some engines have the pin offset by about .050" to make the engine a little quieter by putting a little preload on the thrust side of the piston to prevent piston slap on compression as the piston rocks across TDC. The preload on a six should be toward the left hand (drivers) side of the engine.
However, from what I'm reading/understanding is that the preload is on the opposite side from the pin.
Having the pin slightly to the left will apply preload on the right. So, with the pin on the passenger's side (which it is) it applies preload on the driver's side.
Unless I'm not understanding that correctly. And if I'm not, I want to find out much sooner than later.
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From: Boise, Idaho
Yeah, I found that illustration on line and it was the most useful I could find at explaining it. Interestingly, there's not a lot of data on the subject. Most everything I could find was simply people asking if they're orienting the pistons in their engine correctly. Not how it actually worked.
So, hopefully, I'm understanding it right.
So, hopefully, I'm understanding it right.
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I've never seen or found any of those oil pan or valve cover rails. I'd love a set, so I may have to venture out again and see if I can find some. They'd definitely be great. I know I've already had to get rid of both a pan and valve cover because the areas around the bolts were so mushroomed.
Lead Driver
Joined: Mar 2008
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From: Near Los Angeles
Hey, AB, I was concerned about the pin issue and posted over at fordsix, and Pmuller9 responded, the same guy who was teaching me about cams in my 351 pistons thread. Here is what he wrote:
In a 300 six as well as the rest of the engines that turn clockwise from the front view, the major thrust side of the cylinder wall is the passenger side.
You want the piston pin set toward the major thrust side (Passenger side in this case) so when the crank position is at TDC the connecting rod is already at an angle pre-loading the piston into the major thrust side cylinder wall.
It will run quieter over a non-offset pin especially when the piston is still cold.
So, to my understanding, you (we) are good to go!!
In a 300 six as well as the rest of the engines that turn clockwise from the front view, the major thrust side of the cylinder wall is the passenger side.
You want the piston pin set toward the major thrust side (Passenger side in this case) so when the crank position is at TDC the connecting rod is already at an angle pre-loading the piston into the major thrust side cylinder wall.
It will run quieter over a non-offset pin especially when the piston is still cold.
So, to my understanding, you (we) are good to go!!
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From: Boise, Idaho
Those'd be great. Thanks for the offer.
Thread Starter
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Moderator
Joined: Dec 2007
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Likes: 104
From: Boise, Idaho
Hey, AB, I was concerned about the pin issue and posted over at fordsix, and Pmuller9 responded, the same guy who was teaching me about cams in my 351 pistons thread. Here is what he wrote:
In a 300 six as well as the rest of the engines that turn clockwise from the front view, the major thrust side of the cylinder wall is the passenger side.
You want the piston pin set toward the major thrust side (Passenger side in this case) so when the crank position is at TDC the connecting rod is already at an angle pre-loading the piston into the major thrust side cylinder wall.
It will run quieter over a non-offset pin especially when the piston is still cold.
So, to my understanding, you (we) are good to go!!
In a 300 six as well as the rest of the engines that turn clockwise from the front view, the major thrust side of the cylinder wall is the passenger side.
You want the piston pin set toward the major thrust side (Passenger side in this case) so when the crank position is at TDC the connecting rod is already at an angle pre-loading the piston into the major thrust side cylinder wall.
It will run quieter over a non-offset pin especially when the piston is still cold.
So, to my understanding, you (we) are good to go!!
and it's good to know the benefits of them.
Posting Guru
Joined: Jun 2012
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From: Mims, FL
I'm glad this has been brought up and clarified. I would not have thought about it if choosing a V8 piston, so it's good to know, and that it's workable if an offset choice is made. Also glad to read that yours is installed correctly!
What's the timeline for finishing the engine and getting it installed?
What's the timeline for finishing the engine and getting it installed?
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From: Boise, Idaho
Me too fljab, especially since I didn't even know they offset piston pins, so it really caught me off guard, long after they'd been selected, balanced, installed, etc. So, I'm glad there wasn't an issue or I'd have some redoing to do.
But, from what I've learned about it, it seems that any 351w piston will work in a 300, if the pin diameter and height is correct.
Not sure on a timeline yet. I'm gathering "install" parts as time allows. I have another chunk of stuff that'll be showing up today. Piston length checker, new oil pump sump tube, some gaskets, etc. Hopefully the paint I ordered will show up soon so I can spray it down and start putting it together!
But, from what I've learned about it, it seems that any 351w piston will work in a 300, if the pin diameter and height is correct.
Not sure on a timeline yet. I'm gathering "install" parts as time allows. I have another chunk of stuff that'll be showing up today. Piston length checker, new oil pump sump tube, some gaskets, etc. Hopefully the paint I ordered will show up soon so I can spray it down and start putting it together!
Lead Driver
Joined: Mar 2008
Posts: 7,165
Likes: 375
From: Near Los Angeles
AB, I'm curious. My set of the same pistons says 'balanced set' on the label. Did yours need much balancing? I was going to install mine as is ... now I have to ck them. Always best to ck.