Will this buildup require balancing?

[TrickFlow]

I finally got the cash together to finish my engine buildup. I had the shortblock put together, but i realized that back when i got it machined and put together, it wasnt balanced..
I was told by a few people that if i shift over 6 grand, i should get it balanced, and others say that anything over a 5 grand shift requires balancing.. i dont see how thats right when i was shifting at 5400 stock. Im just wondering, if i do need to get it balanced, ill have to wait a month to get it back they said.. they have alot of people in front of me... but if not, i can have the car running in just over a month. im willing to take the time and get it done right if its needed.
When im at the track (maybe once a month or so) ill probably be shifting at 6 grand, and drivin the car mostly on weekends.. here is a list of the mods to help out:

-Block Bored and honed to 306
-Trickflow 10:1 forged pistons
-Polished crank
-Trickflow Track Heat Heads
-RPM Air Gap intake
-Holley 600cfm double pumper
-Trickflow 6.700 pushrods
-Trickflow stage II cam ( duration 224*/232* lift .542"/.563")
-FMS lifters
-Hooker 1 5/8 Longtubes
-Scorpion 1.6 rockers



Thanks in advance for any help!

 

[Boss 351]

Balancing is needed if you change the piston / rod weight. So you got 30 over pistons which will be heavier than stock so yeah I'd say you need a balance job! If you want do do it right.

 

[TrickFlow]

I just dont want to get the car running, take it to the track, and blow it the hell up... just because i was in a hurry to get it done ( i mean its only been in the garage for 2 1/2 years ) but im excited to finally get it done, just getting down to the nitty gritty parts now.
The guy thats doing the balancing was an engine tech in nascar in the late 80's early 90's, and opened a shop here... from talking to him this morning, he wants my balancer, pistons/rods, clutch/pressure plate/flywheel etc when i bring it in.. he wants everything, so i believe i can trust him to do it right. i just hate waiting a month when i could be sticking parts on at the end of next week

 

[Boss 351]

Yeah I know the feeling but your engine will run smooth and won't loose power due to vibrations. I didn't send my clutch and pressure plate to the balance shop, just the crank, rods, pistons, rings, etc.. balancer and flywheel.

 

[TrickFlow]

I wasnt sure why he needed all of it, but a friend of mine had his motor done thru the same guy, and said that if you gave the dude a cigarette, he could balance it.

 

[TrickFlow]

Anyone else have any input before i send this thing off?

 

[txstang84]

the clutch ass'y is seldom, but sometimes out of balance and your machinist just wants to make damn sure your engine will live at high rpms...vibration is has some hugely bad effects on an engine as we all know...the reason he needs all the rest of the stuff though is cuz Ford SB's are external balance, they can't put enough mass into the counterweights from the factory to balance out the weight of the piston and rod ass'y's...so they put weights on the balancer and flywheel...

the clutch is neutral balance but he probably wants to mate it to the flywheel during balancing to make sure all's right with the guts

i'd say give it all to him

 

[TrickFlow]

Ok... thats two votes "yes" so ill probably go with that then.... you in Texas im takin it? if so, where at?

 

[cobradvm]

You MUST balance it - whoever put the rotating assy in without balancing it, is doing some half assed work. As said above, if not balanced, it will eventually shake itself apart. In order to balance it properly, he will need every thing from the flywheel forward including the balancer. You don't need to send the pressure plate/friction disk in - the reason he needs you flywheel is that he may need to alter the imbalance weight on it - then if you need to change your flywheel, you must reuse that same weight. He shouldn't touch the pressure plate (ie remove or add weight to it) because you may change that at some point, and it should be interchangable with out having to pull the engine and rebalance the whole setup again - make sense? He may just bolt it on to make sure it is all balanced, but he shouldn't be doing anything to it.

 

[txstang84]

You MUST balance it - whoever put the rotating assy in without balancing it, is doing some half assed work. As said above, if not balanced, it will eventually shake itself apart. In order to balance it properly, he will need every thing from the flywheel forward including the balancer. You don't need to send the pressure plate/friction disk in - the reason he needs you flywheel is that he may need to alter the imbalance weight on it - then if you need to change your flywheel, you must reuse that same weight. He shouldn't touch the pressure plate (ie remove or add weight to it) because you may change that at some point, and it should be interchangable with out having to pull the engine and rebalance the whole setup again - make sense? He may just bolt it on to make sure it is all balanced, but he shouldn't be doing anything to it.

yeah, i'm in Abilene, there's a couple of really good machine shops here-last fall we took the machinist a stock bottom end...stock crank, rods, pistons from a H.O., they said it was a little off, you could see where they drilled a couple small divits in a couple of counterweights, and put some weight into another one...it runs like a dream

yes and no with the pressure plate/clutch, obviously you are going to have to change it sometime, but he probably wants to "zero it out" by itself to make sure it won't affect the balance on the reciprocating ass'y since it will be attached to it (the machine shop I take all my parts to recommends it as well for longevity-they are supposed to be zeroed, but hey ya know manufacturing differences yield weight imbalances). ideally you should have the flywheel resurfaced when you install a new clutch as well-common knowledge-which can potentially alter the balance. the same place i just mentioned just resurfaced the flywheel, ck'd the balance there with no alteration, and took out or added weight to the crankshaft as needed, and zero'd all the piston/rod ass'y's to the lowest weight for $220.

outstanding machine work on his part

 

[TrickFlow]

Awesmoe, thank you guys for all the information

 

[vristang]

I agree that you should have it balanced. In fact it is recommended to do this anytime you change the pistons or rods.I thought I would add this for consideration though.

I have it from a very good source that there are no longevity or hp advantages to balancing a motor, and the only advantage is to eliminate the shaking that can get pretty bad at a certain rpm. I am not sure I agree with this entirely. However, the only data I have seen which shows these advantages have been from balancing shops.

The source is the head of the Automotive Design department at the Univerity I attended, who has a masters degree and has been building/racing/rebuilding not just engines but entire cars for probably 50yrs. And when I say building engines I mean fabricating a V-12 engine block from Carbon Fiber and machining each head out of 2 Al billets. The guy knows some stuff.

Just thought I would throw this out as something to think about.

 

[TrickFlow]

hey im open for any info, and that is glady taken... i think im just gonna take it to him and spend the few hundred to get it done... so if the motor did ever come apart, ill know it wasnt because i saved 250 bucks, by not getting it balanced