when i have an engine built i like to see the rods whiten one to one half a gram, even for a street motor. But i am just very **** like that.
connecting rod weight variation
Thread Starter
Pro
Joined: Jun 2009
Posts: 613
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From: Fleetwood PA
connecting rod weight variation
I'm prepping the rods on my 454 build. I know it should be as close as possible, but what would you consider the max weight difference in the rods and still be ok for a mild street motor?
I weighed them all and from lightest to heaviest I have about a 5 gram difference....with most being within 2 grams. Is this ok or should I do some shaving?
I weighed them all and from lightest to heaviest I have about a 5 gram difference....with most being within 2 grams. Is this ok or should I do some shaving?
Instructor
Joined: Mar 2010
Posts: 121
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From: Dallas Texas
Five grams is pretty close to the no-go line, but it really depends on what you consider mild... what rpm's will you be running? That is what really decides how much offset weight you can run. Regardless of the application, if you have the resources available to grind the rods, and know what you're doing, i'd match them to within one gram.
Last edited by True Blue Vette; Mar 31, 2010 at 11:11 PM.
Thread Starter
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Joined: Jun 2009
Posts: 613
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From: Fleetwood PA
It's just a street car that won't see more than 6000 rpm. They are the stock "thumb" rods, and have plenty of meat on the top and bottom that I can shave a little here and there to get them within a gram or two. I know that most balanced sets shoot for 1 gram, but I wasn't sure how crucial it was in a street motor.
These rods have a large "****" of metal on both the top and bottom. Is there a better end to remove the metal from, or should I take a small amount from each end a little at a time till I hit my weight?
These rods have a large "****" of metal on both the top and bottom. Is there a better end to remove the metal from, or should I take a small amount from each end a little at a time till I hit my weight?
Last edited by whitehause; Mar 31, 2010 at 11:32 PM.
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From: Kalamazoo Mi
Thread Starter
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Joined: Jun 2009
Posts: 613
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From: Fleetwood PA
I just did a little more research on this and saw a nice you-tube video that shows the whole process. They have a hanging jig to put the ends in. they balanced the small first, then the big end. Looks pretty straight forward. I guess today will be jig building day! thanks for all the info guys!
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Team Owner
Joined: Jan 2006
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From: Crossville TN
For an engine that won't see over 6000 rpm, don't worry about it. If it were a racing engine that sees 6500-7000 all the time, balance is important to longer life and a bit more power. And, if this is not something you are familiar with, just grinding metal off of your rods is not a simple task to do correctly. Take it off the wrong place and/or in the wrong way, and you end up with a broken rod when you crank it up. Removing metal can be a much worse situation than not removing metal, if you do it improperly.
Thread Starter
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Joined: Jun 2009
Posts: 613
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From: Fleetwood PA
These stock thumb rods have a healthy amount of metal on the balancing pads (about 1/4" or more on both ends). I have a good scale. The jig looks pretty simple to make, so I think I should be ok. From what I have seen, you get the small ends balanced first using your lightest as your target number. Then use the big end to get the whole rod in balance, again using the lightest as your target number. I think if I just work slowly,grind with the grain, and check often it shouldn't be too hard to get them pretty close to 1 gram at least.
