Balancing Q's
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From: Broken Arrow OK
Balancing Q's
Ok guys, I'm getting ready to put my 355 togethor.... I have a question about balancing. I'm using the stock crank and rods with new pistons...should I have it all balanced? I'm thinking so. Also, what main and rod bearings have you had luck with? I'm thinking Clevite 77 H's. I'm using a L98 Block, crank and rods.....all from same engine.
Thanks everyone!
Thanks everyone!
Burning Brakes
Joined: Feb 2005
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Balancing and Bearings
The unit should be balanced for 2 reasons. First, your changing pistons, which by itself, is not an issue as long as they're very close to the original weights, but secondly, you have no way of knowing how "good" the original balance was from the factory. They tend to make things only comfortable. As for the bearings, if you're using the stock crank, don't throw your money away with "chamfered" bearings, you don't need them. The Clevite's "P" series is more than adequate. Thanks, Gary in N.Y.
Race Director
Joined: Dec 1999
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From: Forked River NJ
I took a factory GM replacement LT1 apart and had it balanced. It was off from the factory. Imagine that. I would not put an engine together without balancing it. Mine will turn 7000 rpm with no problem and smooth as can be.
Race Director
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From: Forked River NJ
Going back a few years it cost me around 225 for the balance alone. Now they reworked the rods and polished the crank and took the pistons off/on the rods so this all cost extra. It was around 400 if I remember right for the whole deal. Worth it if you are going to spin the motor. It will just run smoother.
Burning Brakes
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Pricing/Balancing
Originally Posted by apokesfan
What can I expect to spend on balancing?
Le Mans Master
Joined: Sep 2003
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From: eastern NC
With the exception of some very low production high performance optioned engines, factory balancing was a ball park thing. The degree of factory balancing was determined primarily by what the maximum rpm the engine was expected to run at. Most engine builders will want to balance an engine to a much lower variation in component weights. They’re trying to minimize the amount of parasitic horsepower lost to the engine. It won’t necessarily increase overall horsepower, but it will make more of that produced, available to your rear wheels.
Most of us will not be able to actually feel a difference, vibration wise, in the balance of an engine. After all, the factory didn’t ordinarily do that bad a job. But what you might feel is that the engine now revs more freely and it will surely survive an over-rev it might not have survived before.
While it may not have the bling of a polished intake manifold or a show quality paint job, the peace of mind it can give you is well worth the cost. I believe that balancing an engine assembly is one of the best values out there for making horsepower you can live with.
GUSTO
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Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
Balancing is a "nice to have" for that engine. TONS of engines have been rebuilt like this one without a balance job. They do not fall apart or vibrate your teeth out. They just run untill you sell the car and buy some other money pit. 
Use standard chamfer bearings, nothing fancy. Chamfered bearings are only required for custom ground cranks with larger than stock fillet radius ground into them. That is the only reason to use them. The larger fillet radius ground into the crank will add some strength but not many of us regularly break crankshafts.
If you want to spin it or if you can afford the cost of the balancing, do it.
As always, JMO.
-Mark.
Use standard chamfer bearings, nothing fancy. Chamfered bearings are only required for custom ground cranks with larger than stock fillet radius ground into them. That is the only reason to use them. The larger fillet radius ground into the crank will add some strength but not many of us regularly break crankshafts.
If you want to spin it or if you can afford the cost of the balancing, do it.
As always, JMO.-Mark.
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From: Broken Arrow OK
Originally Posted by GOSFAST
In our neck of the woods, Long Island, it would probably run about $200.00 for the balancing alone. If the shop doing the job is really sharp, they may be able to avoid pressing the pistons off and on again. This is risky when trying to reuse the pistons. Normally you press the old ones off, discard them and the pins, and install the new ones. Once in a while, the pins "gall" the pistons on the way out and you end up needing oversize pins installed in the new pistons to correct everything. As I said, if the engine shop is "sharp", it can be done with the pistons as they are. Thanks, Gary in N.Y.
Here's another question....while I'm going to the machine shop....should I just go ahead and jump into a 383? I'm trying to use the new parts I already have..... but would entertain buying another crank and having the machine work done. But....will the pistons I already have work in a 383? I've got Speed Pro L2256F. If I recall, I can use 350 rods and pistons on the 400 crank.
Burning Brakes
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L2256 Pistons vs. 400 Crank
We build NO units with "offset" pins anymore (L2256F's). They simply consume horsepower. A better choice would have been the L2417F's with "centered" pins. Worth some "free" horsepower. Your components, the 350 pistons and the 400 crank are not compatible. You are "locked-in" to staying with the 350 crank if you want to run those pistons. Thanks, Gary in N.Y.
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From: Broken Arrow OK
Originally Posted by GOSFAST
We build NO units with "offset" pins anymore (L2256F's). They simply consume horsepower. A better choice would have been the L2417F's with "centered" pins. Worth some "free" horsepower. Your components, the 350 pistons and the 400 crank are not compatible. You are "locked-in" to staying with the 350 crank if you want to run those pistons. Thanks, Gary in N.Y.
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