my engine was originally a 289 but has been rebuilt and bored to a 302. just wondering if the flywheel would be a 28 oz imbalance or a 50 oz imbalance

 

28

 

Bored a 289 to a 302? That's an interesting proposition since 289's and 302's are the same original bore (4.00) and the strokes are different (289 stroke is 2.87, 302 stroke is 3.00) and the max overbore is .060" which gets a 289 no where close to a 302. Seems to be a confusion factor here. Or you have been sadly misinformed.

 

Just a question, what would a .060 overbore get you??

 

a not-so-reliable engine. the bigger the overbore the thinner the cylinder walls making them more apt to warp and crack from heating and cooling, thus destroying the motor.

now, if it's strictly for racing and money is not a factor, it will get you a damn good motor!

i used to know the formula to figure it out, but can't work it out. i'm forgetting something. i know it's bore x stroke and than something else.

 

(PI* R2)* stroke

 

297.25 cu in

 

but unless i'm doing something wrong, that doesn't figure out right. i have been told numerous times a 302 with a .030 overbore is a 306, but with this it figures out to be a 304 and a .060 overbore figures to be a 306. did i miss something?

 

I was figuring the shorter stroke of the 289, not the 302.

 

Back to his question. First you need to make sure the block is pre 1980 and if so, you would use a 28 oz.. If the date code is later then 1980, you use a 50 oz.