Custom built short block. Can have either 28oz or 50oz balance. Which is better?

Joey7508 · Oct 30, 2005

Looking for a short block. Probably going to be a 331. Possiably 347. CHP shows that you can have either balance 28 or 50. They will buikd them either way. Which is better what is the benifit of either. Some on told me 28 oz was better but did not say why. Help?

giddyup306 · Oct 30, 2005

It is determined on how the crank is balanced. I run a 50oz in my 347. Although FRPP crate motors have a 28oz. I personally think it provides a smother idle than a 28 because its weigh is more able to counter the crank harmonics.

bubba-dough · Oct 30, 2005

"They" say doing a 50 oz takes to much material from the crank and leaves it like "swiss cheese" which in turn could make the crank less durable. Whatever...my crank is a 50 oz balance by Coast (btw, they told me there is no difference in durablity between the 28 and the 50) and there was only like 3 spots and all of which were not very deep at all and they were not in any way put in an "iffy" place.

65ShelbyClone · Oct 31, 2005

If you're getting a new damper and flywheel, then just go with 28oz if the prices are the same. There is less material on the damper, crank, and flywheel acting as a counterweight and its a little closer to a zero balanced engine.

BTW- cranks start looking more like swiss cheese the closer they get to zero balance, especially if one started as a 50oz.

Grn92LX · Oct 31, 2005

Go 28oz 347. Its less weight hanging off the end of the crank.

Rick 91GT · Oct 31, 2005

Depends on how heavy the crank is but if you go 50oz it could have a lot of balance holes in the counter weights. Cast cranks can go 50, 28 usually with no issues, the forged cranks are better at 28 or 0 depending on the brand you use.

Personally if your upgrading your balancer and flywheel/flexplate go 28 or 0/internal and keep the weight off the snout.

$uperstang · Oct 31, 2005

Mine is all Forged and 50oz. balanced. Works great! It really does not matter.

stangnutlx · Oct 31, 2005

i got my CHP 306 balanced at 28oz.... CHP makes a real nice shortblock....

304billet · Oct 31, 2005

A 28oz imbalance is OK in ur application. The crank and rods r balanced externally to the 28oz damper and 28oz flywheel. A 50oz crank is not any stronger than a 28oz crank or a neutral balanced crank.

A neutral balanced rotating assembly is balanced internally. The crank, rods and pistons are balanced together. Each rod and each piston weigh the same and the crank is drilled and filled with mallory to get the correct bobweight.

A neutral balanced engine will spin higher rpm's and last longer than an externally balanced engine. Costs range from $400-$800 depending on how much mallory is added. Most drag race and road race engines r neutral balanced.

clarkjr · Oct 31, 2005

Rick 91GT said:
Personally if your upgrading your balancer and flywheel/flexplate go 28 or 0/internal and keep the weight off the snout.

Depending on the assembly, I'd go zero and do it internally as Rick said. But 28 vs. 50, do the 28.

vikingpower · Oct 31, 2005

If you're getting a custom shortblock, just go all the way and get it internally balanced, its worth the $$$

Modular2v · Nov 1, 2005

my 331 is 50oz because i didnt want to have to buy a new balancer haha

90mustangGT · Nov 1, 2005

I went 28oz with my 347 from rick because the cost of balancing is almost as much as a new flywheel and balancer, and I can sell my balancer and make up for it, so not a total loss. Yes, less bobweight does take stress off the crank, especailly at high RPM's. I have not heard of the bobweights of our cranks causing real issues.

Modular2v · Nov 1, 2005

i would ask rick and go with his answer

Custom built short block. Can have either 28oz or 50oz balance. Which is better?

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