Measuring Connecting Rods
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Le Mans Master
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From: Akron Ohio
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St. Jude Donor '09-'10-'11
Measuring Connecting Rods
On my rebuild Im looking to make power past 6000 RPM but I dont think the stock rods will take it. My dad has some really nice rods he isnt using and offered them to me for my engine, but he forgot what length they are. I would assume the 5.7" or 6.0" length is measured from the center of rod hole to the center of the wrist pin hole, but I dont want to end up being wrong. Can someone confirm how to measure the length for me please? 
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Le Mans Master
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
Thanks. Yes just 5.7 or 6. They were in a 408ci for a very short time and then that car was sold and we kept the engine. Now he has no use for the engine so I am going to borrow parts from it. The chevy 400 originally came with short 5.5" rods so when we built it we got longer ones, just dont remember if they were 5.7 or 6".
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Le Mans Master
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
I am hoping they are 5.7 so I can use my factory pistons, if not it would still be cheaper to use the rods and get new pistons than buy all new. The factory rods wont last past 6K RPM
I know there are other sizes, but I also know these are not special. When we ordered them they were either 5.7 or 6 I just cant remember. I have not torn into the 408 to get the rods out yet.
I know there are other sizes, but I also know these are not special. When we ordered them they were either 5.7 or 6 I just cant remember. I have not torn into the 408 to get the rods out yet.
Team Owner
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
There are lots of good aftermarket 5.7" rods available that will easily handle high RPM. Even the old Chevy "pink" rods were good for rpm's way above 6K.
Check with your machinist to see what all is involved in using a 6" rod in a stock 350 short-deck block. I think there may be more than just a thinner piston involved. Carefully check the rod bolt clearances for the inside of the oil pan rail, the camshaft lobes and piston skirt clearance. Also very carefully check the compression height of the piston at the top of their travel. You may need pistons with more relief to avoid valve-to-piston interference.
The 6" rod will provide more torque but the engine may not be as quick to gain revs off idle. You will get higher RPM's and 6" rods will work even better with more cubes like that 408.
Check with your machinist to see what all is involved in using a 6" rod in a stock 350 short-deck block. I think there may be more than just a thinner piston involved. Carefully check the rod bolt clearances for the inside of the oil pan rail, the camshaft lobes and piston skirt clearance. Also very carefully check the compression height of the piston at the top of their travel. You may need pistons with more relief to avoid valve-to-piston interference.
The 6" rod will provide more torque but the engine may not be as quick to gain revs off idle. You will get higher RPM's and 6" rods will work even better with more cubes like that 408.
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Le Mans Master
Joined: Oct 2007
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
There are lots of good aftermarket 5.7" rods available that will easily handle high RPM. Even the old Chevy "pink" rods were good for rpm's way above 6K.
Check with your machinist to see what all is involved in using a 6" rod in a stock 350 short-deck block. I think there may be more than just a thinner piston involved. Carefully check the rod bolt clearances for the inside of the oil pan rail, the camshaft lobes and piston skirt clearance. Also very carefully check the compression height of the piston at the top of their travel. You may need pistons with more relief to avoid valve-to-piston interference.
The 6" rod will provide more torque but the engine may not be as quick to gain revs off idle. You will get higher RPM's and 6" rods will work even better with more cubes like that 408.
Check with your machinist to see what all is involved in using a 6" rod in a stock 350 short-deck block. I think there may be more than just a thinner piston involved. Carefully check the rod bolt clearances for the inside of the oil pan rail, the camshaft lobes and piston skirt clearance. Also very carefully check the compression height of the piston at the top of their travel. You may need pistons with more relief to avoid valve-to-piston interference.
The 6" rod will provide more torque but the engine may not be as quick to gain revs off idle. You will get higher RPM's and 6" rods will work even better with more cubes like that 408.
Clearance for the cam and piston and everything should be fine, Im not going too radical lift wise and Aardwolf on here just built an engine using 6" rods without any issues.
Again, since this is a roadrace off idle is not too much of a concern.
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Le Mans Master
Joined: Feb 2000
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From: Kempner Texas
If it were me, I'd run one by a machine shop and have both the Big and Small ends measured as well as the Center to Center length. That data would come in handy to have when choosing pistons and bearings should you end up using those rods.
Jake
Jake
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Le Mans Master
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From: Akron Ohio
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Good idea!
Race Director
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On my rebuild Im looking to make power past 6000 RPM but I dont think the stock rods will take it. My dad has some really nice rods he isnt using and offered them to me for my engine, but he forgot what length they are. I would assume the 5.7" or 6.0" length is measured from the center of rod hole to the center of the wrist pin hole, but I dont want to end up being wrong. Can someone confirm how to measure the length for me please?
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,681
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Race class restrictions require I run a production C4 Corvette 1 piece rear main two bolt block.
Race Director
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Factory stuff varies greatly, and you don't know where you are within their tolerances.
No easy answer to your question.
If you are making less than 500 hp, new bolts, shotpeening and careful machining/balancing of stock steel rods work quite well.
Thread Starter
Le Mans Master
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
You would need to measure the big end of the rod and the small end. Not the total weight. This would be done with a jig and a gram scale. The amount of imbalance would depend on too many things to say "x amount of grams are ok"
Factory stuff varies greatly, and you don't know where you are within their tolerances.
No easy answer to your question.
If you are making less than 500 hp, new bolts, shotpeening and careful machining/balancing of stock steel rods work quite well.
Factory stuff varies greatly, and you don't know where you are within their tolerances.
No easy answer to your question.
If you are making less than 500 hp, new bolts, shotpeening and careful machining/balancing of stock steel rods work quite well.
Team Owner
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From: altered state
St. Jude Donor '05
shotpeened and polished side beams/good bolts should hold...using a lighter piston will help some.
The pink rods were just stock + shotpeened as far as I know. They can take some abuse with good rod bolts.
The pink rods were just stock + shotpeened as far as I know. They can take some abuse with good rod bolts.
Thread Starter
Le Mans Master
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
Good to know. I would really like to avoid buying pistons if I dont have to (I started the thread to see if I needed to using the other rods). The block is being checked by the shop to see how straight the cylinders are. If it doesnt need to be bored Im going to use the factory pistons, (which I thought were lightweight forged from the factory in the later L98s?), if I have to I will get lighter .030 over pistons.As far as bolts the ARP 2000 series are the way to go correct? I found a kit for factory rods on Summit by ARP.
Thread Starter
Le Mans Master
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Oh ok it may have been the early pistons I was thinking of. I knew they were forged at some point.
