Connecting Rod Resize
01-11-2016, 02:22 PM
#1
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Connecting Rod Resize I went to a machine shop to ask about putting ARP rod bolts in my stock connecting rods. The guy was explaining that he can hone a thousandth off of the rod after the ARP bolts are installed, just to true them up. He said I would still use standard size bearings in them after he does this. Does this sound right? I know the there is an oversize OD bearing to use when honing cracked cap rods, but he's telling me that I wouldn't need them.
Please weigh in.
Please weigh in.
01-11-2016, 02:52 PM
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I went to a machine shop to ask about putting ARP rod bolts in my stock connecting rods. The guy was explaining that he can hone a thousandth off of the rod after the ARP bolts are installed, just to true them up. He said I would still use standard size bearings in them after he does this. Does this sound right? I know the there is an oversize OD bearing to use when honing cracked cap rods, but he's telling me that I wouldn't need them.
Please weigh in.
Please weigh in.
If the rods are at the low end of the spec now and when torqued up with the new hardware and honed can then size under the top end of the spec, then yes he is right. There's a little confusion with this because the official spec for the LS/LQ series rods is 2.224"-2.225" but they use the exact same bearing shells as all the previous generation small blocks going back to the 60's for which the spec is 2.2247"-2.2252" If he can finish the rods to under 2.2252" then you'll be fine with the standard CB-663 style bearing which makes it much easier to mix shells and get your oil clearance spot on. Personally I either consider it a stock application and just hone them .002" and use the special bearings, or upgrade the customer to a real performance rod.
01-11-2016, 03:51 PM
#5
Here is the bearing.
http://www.summitracing.com/parts/cle-cb1776a
This is used for what you are doing. I am doing the same thing. ARP rod bolts, so I will resize and use these bearings.
http://www.summitracing.com/parts/cle-cb1776a
This is used for what you are doing. I am doing the same thing. ARP rod bolts, so I will resize and use these bearings.
01-11-2016, 05:48 PM
#6
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So, less than or equal to 2.2252" and stock bearings are fine. Anything over 2.2252" and I need special bearings. The only thing I noticed with the oversize OD bearings, is that I only see them for STD crank journal diameter. My crank was cut 10 thousands under.
Great info though, thank you!
Great info though, thank you!
01-11-2016, 06:09 PM
#7
They make them for .010" under, just add the -10 suffix to the PN.
http://www.summitracing.com/oh/parts/cle-cb1776a108
http://www.summitracing.com/oh/parts/cle-cb1776a108
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01-13-2016, 08:58 AM
#8
I've been fighting this exact issue for a while.
Lot of different opinions on this deal. My first go around I had my rods resized to .002 overbore. Now that im buiding another engine and wanted to run a good quality bearing on a stock journal crank, I wasn't able to find anything except .010 under. I wasn't going to sacrifice using a normal clevite bearing this go around.
My local Tech school engine builder, which does a ton of LS stuff. Sold me a stock set of rods and said they have maybe 1 in 50 rods that go out of spec with ARP hardware. And never do resizing. They throw away rod and get another. or use aftermarket if HP goal is over 700.
So I currently have stock rods/ARP bolts/ ACL bearings. Still confirming my clearances as we speak. Hopefully i'll have solid numbers by Friday.
My suggestion is to install ARP hardware and check your rods with MICs, not plastic and go from there. 2cents
Lot of different opinions on this deal. My first go around I had my rods resized to .002 overbore. Now that im buiding another engine and wanted to run a good quality bearing on a stock journal crank, I wasn't able to find anything except .010 under. I wasn't going to sacrifice using a normal clevite bearing this go around.
My local Tech school engine builder, which does a ton of LS stuff. Sold me a stock set of rods and said they have maybe 1 in 50 rods that go out of spec with ARP hardware. And never do resizing. They throw away rod and get another. or use aftermarket if HP goal is over 700.
So I currently have stock rods/ARP bolts/ ACL bearings. Still confirming my clearances as we speak. Hopefully i'll have solid numbers by Friday.
My suggestion is to install ARP hardware and check your rods with MICs, not plastic and go from there. 2cents
01-17-2016, 07:24 PM
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My local Tech school engine builder, which does a ton of LS stuff. Sold me a stock set of rods and said they have maybe 1 in 50 rods that go out of spec with ARP hardware. And never do resizing. They throw away rod and get another. or use aftermarket if HP goal is over 700.
Any competent machinist will tell you that if you increase the clamp load on a bore you are going to distort it....most times in ways that cannot be seen with a two or even three point gauge...simply put, the rods turn into a square and need to be resized, that guy shouldn't even be teaching people how to change a spark plug.
01-17-2016, 09:02 PM
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In My opinion Plastigage can give false readings if only 1 piece on 1 position on crank/bearing because it can potentially have a tendancy to pull rod/bearing a little to the side with plastigage so what I do is cut 2 pieces and position them directly opposite 1 another on crank and that helps to keep rod/bearings more centered thus more accurate measurements and also with ARP conn rod hardware not only will the tighter clamping force distort the rod big ends initialy but a little more distortion over time can take place so again in My opinion it's that much more important to start with rods as round as possible,,,,,even with stock bolts they distort some over time,,,,,,,good luck
01-17-2016, 10:03 PM
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02-23-2019, 07:20 PM
#13
Teching In
I've been fighting this exact issue for a while.
Lot of different opinions on this deal. My first go around I had my rods resized to .002 overbore. Now that im buiding another engine and wanted to run a good quality bearing on a stock journal crank, I wasn't able to find anything except .010 under. I wasn't going to sacrifice using a normal clevite bearing this go around.
My local Tech school engine builder, which does a ton of LS stuff. Sold me a stock set of rods and said they have maybe 1 in 50 rods that go out of spec with ARP hardware. And never do resizing. They throw away rod and get another. or use aftermarket if HP goal is over 700.
So I currently have stock rods/ARP bolts/ ACL bearings. Still confirming my clearances as we speak. Hopefully i'll have solid numbers by Friday.
My suggestion is to install ARP hardware and check your rods with MICs, not plastic and go from there. 2cents
Lot of different opinions on this deal. My first go around I had my rods resized to .002 overbore. Now that im buiding another engine and wanted to run a good quality bearing on a stock journal crank, I wasn't able to find anything except .010 under. I wasn't going to sacrifice using a normal clevite bearing this go around.
My local Tech school engine builder, which does a ton of LS stuff. Sold me a stock set of rods and said they have maybe 1 in 50 rods that go out of spec with ARP hardware. And never do resizing. They throw away rod and get another. or use aftermarket if HP goal is over 700.
So I currently have stock rods/ARP bolts/ ACL bearings. Still confirming my clearances as we speak. Hopefully i'll have solid numbers by Friday.
My suggestion is to install ARP hardware and check your rods with MICs, not plastic and go from there. 2cents
Think of it like this, imagine that you have a set of brand new tires on your car but they weren’t balanced. Now driving around town say at 35-40 mph your probably not going to notice anything but when you get on the highway the car will start to shake like crazy. Now imagine a unbalanced stock engine. Your average person with a daily driver isn’t going to notice it, now you decide that you want to double the horsepower, and take it up to 7,000 rpms if you don’t take the time to balance it precisely then you might start having problems above 6,000 rpms. The main problem with rod failure IMO is because of balancing. The higher rpms cause a lot more vibration which causes the rod to fail in a unbalanced engine. You can have the best bolts in the world and they might still break. Also on a LS anything over 7,400 rpms should have performance rods, pistons and crankshaft. There are too many variables as to why a engine fails. As a performance engine builder for the last 20 years I can honestly say that if you don’t get your numbers correct including balancing for the application you are using it for you will have a failure.
02-23-2019, 08:13 PM
#14
I totally couldn’t agree more. Unless you’re going over 700 hp (which on the street would be insane) on a LS engine then using the stock pistons and rods are more than enough. Your instructor is a very wise man! The engineers really did their homework for the LS. These engines are designed with a lot better machine work and equipment than the Gen. l. These aren’t the engines from the 60’s and they can handle a lot more horsepower than most people think. The major key in a high reving engine is balancing. I won’t get into my specifications in balancing but it must be done correctly with the whole rotating assembly. Even if you take it to a machine shop for balancing you should always double check their work. If you don’t have the equipment to check then send it to a second machine shop to double check. I actually like to be present when they dynamically balance my crankshaft because it puts them on their toes and they focus more. This is the only part of the balancing that I cannot do because I don’t have the equipment to balance the crankshaft.
Think of it like this, imagine that you have a set of brand new tires on your car but they weren’t balanced. Now driving around town say at 35-40 mph your probably not going to notice anything but when you get on the highway the car will start to shake like crazy. Now imagine a unbalanced stock engine. Your average person with a daily driver isn’t going to notice it, now you decide that you want to double the horsepower, and take it up to 7,000 rpms if you don’t take the time to balance it precisely then you might start having problems above 6,000 rpms. The main problem with rod failure IMO is because of balancing. The higher rpms cause a lot more vibration which causes the rod to fail in a unbalanced engine. You can have the best bolts in the world and they might still break. Also on a LS anything over 7,400 rpms should have performance rods, pistons and crankshaft. There are too many variables as to why a engine fails. As a performance engine builder for the last 20 years I can honestly say that if you don’t get your numbers correct including balancing for the application you are using it for you will have a failure.