whats the difference between a 65 425(386525) vs 70 455(olds 98)

 

30 cubic inches
425 shorter stroke
425 steel crank
425 different flywheel bolt pattern
425 different lifter size in some
425 cam bank angle in some
some like the 425 better
455 more popular
455 longer stroke
455 has 30 more cubic inches
455 has more parts available

for the most part they both are great engines. go for it

Gene

 

I agree with Gene, both are great engines. From the outside they look pretty much the same and will bolt in place the same. It may come down to personal preference. John

 

Even though I like the 425's I would go with the 1970 455. If it's out of a Olds 98 it is a 365 HP engine around 500 ft torque, nice street engine. The 1965 425's had an 'odd-ball" adjustable rocker arm system, hard to find parts for.

 

425s rev quicker than 455s. 1965 used A heads, 1970 E heads.

 

That sums it up.