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Author Topic:   400 balance
Oldsmobile13
Dirt Maniac

Total posts: 108
posted December 03, 2001 06:21 PM
Id like to build my 400 with 5.7 rods, but if i do (will i have to have it balanced?) I cant get to much money wrapped up in it, so would i be better off to build a 350 or 383 what do you guys think?

Donnie Ross
Dirt Maniac

Total posts: 109
posted December 03, 2001 06:29 PM
mine has ran 5 years with 5.7 rods and speedpro pistons turning 7000 no failures.factory balacer and flexplate.
older racer here won many track championships with this set up claimed he ran 7300 all the time without failure on alky even.

Oldsmobile13
Dirt Maniac

Total posts: 108
posted December 03, 2001 07:37 PM
without balancing it?

Homer62
Dirt Roller

Total posts: 10
posted December 03, 2001 10:33 PM
Olds'13, the cost effective method I've used with good success: use pistons made as a set, the same with rods. Take the 400 balancer, crank and flexplate-flywheel, along with a piston, pin, one set of rings, rod and rod bearings to a shop with that balances such. Have the parts weighed in order to arrive at a bobweight.My machinist then assembles bobweights and spins the crank, correcting the balance as a package. We run sizes from 302's to 400's, OEM cranks only in a modified, and haven't broken a crank or a block in five years. Good luck racin'..

Oldsmobile13
Dirt Maniac

Total posts: 108
posted December 05, 2001 04:57 PM
Is it something i ABSOLUTELY have to do if i keep it under 7000?

istock59
Dirt Freak

Total posts: 237
posted December 06, 2001 07:16 AM
Absolutely? No. But do you want it to last?

I'd never consider running an unbalanced motor. Russian Roulette, in my opinion.

ford5
Dirt Freak

Total posts: 298
posted December 06, 2001 07:41 AM
Olds13 ihave run this combo many times with no balanceing it is always good to keep revs below 7000 bal or not when you are using stock parts it is far more important to spend your $$$$ on good quality machine work such as crank grinding and rod work and most of all a good oil pan!!! keep total timing back too too much timing always kills rods and brgs

dirt mod 70
Dirt Full Roller

Total posts: 59
posted December 20, 2001 02:49 PM
FOR GODS SAKE......SPEND 100.00 TO HAVE IT BALANCED!!!! best insuranse money can buy.

poboy2
Dirt Freak

Total posts: 219
posted December 20, 2001 05:38 PM
I agree! Its actually $150 bucks where we get it done, but still. If your got 7g's in it, whats another bill and a half?!?!?!?

dirt mod 70
Dirt Full Roller

Total posts: 59
posted December 20, 2001 10:05 PM
I balance every motor!!!!! from a junk 1500.00 claimer motor to my 10,000.00 434ci. no $$$$$ better spent.even if you can only build a cheap motor...balancing will extend the life big time!! I know people don't do it and say they ran a motor for 2 years and it was fine....just plain lucky I say!! why blow up even a 1500.00 motor when it probably wouldn't have if it was balanced!!

my .02 cents worth again....LOL

ford5
Dirt Freak

Total posts: 298
posted December 20, 2001 11:08 PM
yes... but you dont put full coverage insurance on a 500 dollar car do you? lol

PURESTOCK 46
Dirt Roller

Total posts: 12
posted December 23, 2001 11:18 PM
DOES BALANCING THE ENGINE HELP MAKE IT FASTER OR BETTER? OR IS IT JUST FOR DURABILITY. I WAS TOLD THAT A BALANCED ENGINE WOULD HAVE A QUICKER THROTTLE RESPONSE. THANKS

sdhnc29
Dirt Freak

Total posts: 467
posted December 24, 2001 01:16 AM
Yes actually ! Balancing will make your engine faster and better . With an engine that is severely out of balance , your frictional horse power loss is increased . Also , the life span of your internal parts will be greatly reduced . Here is a simple example of what I mean . Take your wife's washing machine , pile a bunch of clothes inside , let them wash , and just before the spin cycle , take half the clothes and move them to one side of the machine . Now you have an out of balance situation . What happens next is the house sounds like its going to fall apart , and your wife will probably be slapping you . So balance the load , save the washing machine from self destruction , and run so your wife doesn't think you had anything to do with what just happened .....LOL This is an extreme example , but the theory is the same . If something is severely out of balance , then it's going to break something sooner or later . Factory balancing is very crude . Your average grocery getter will never see more than 4,000rpm , so the factory tolerance for rod and piston balancing can vary quite a bit , usually 5-10 grams on rods , and 2-5 on pistons . It doesn't sound like much , until you turn this into a race engine , go to a piston that is 10-50 grams heavier or lighter , and a pin that's heavier or lighter , and rings that are heavier or lighter , etc. etc. Now you have a crank that is factory balanced for a 1,900gram bob weight (example) , and your new engine , with all your new parts , comes up with a bob weight that is only 1,700 grams . Add the 200 gram difference for each rod journal , and you have a rotating mass that is 800 grams lighter than the counter weights on your crank are balanced for . If this is the case , at 6,500 rpms you will have problems ! My advise is balance any engine that you will be racing with . It's money well spent ! I know that it's not in the budget for some racers , so if you can get a gram scale , balance your own rods and pistons , and supply your engine builder with a bob weight total , then usually there will be a price break for balancing the crank only . For instance , my standard balance job will cost $150.00 . If I have bob weight totals , and all I have to do is make up the weights , and balance the crank , then the cost is dropped to $75-$100 , depending on how far out the crank is . This is now less than the cost of your average racing tire , and it will last a heck of a lot longer .

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Hendren Racing Engines
Rutherfordton , NC
(828)286-0780

PURESTOCK 46
Dirt Roller

Total posts: 12
posted December 29, 2001 09:43 PM
THANKS FOR THE REPLY
MAKES A LOT OF SENSE


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