250ci or 230ci

My engine casting number research reveals my motor to be a Chev/Olds 64-76 230-250ci by casting number 3921968 . Without looking at the pistons, is there a way to find out if it is a 230 or 250ci? Also, if I want to do a direct swap with a new engine , does it matter for compatibility, If my existing motor is a 230ci can I just drop a 250ci without modifications? Thanks, EdD

There will be a set of numbers/letters stamped on the ledge of your block next to the distributer clamp. A 230 and a 250 (obviously) share the same block casting and are interchangeable in our vans. Make sure to keep all of your current motor mounting and linkage hardware for a swap. I have read where some have used a bendable wire (or similar method) to measure the length of stroke thru a spark plug hole. The 250 has a longer stroke.....3.75" vs 3.50"?? DOUBLE check me if you resort to this method.

Thx Steely, I wrote down the numbers. I haven’t figured what all the rackett with my motor is but I think if I need to replace it, I don’t know why I wouldn’t go with a 250ci. I looked at a 350ci with a 2 speed auto a builder wanted to sell me but this van’s character is its being completely unmollested. Hopefully nothing serious though. edD

What year van do yo have?
If you get the casting date found near the dip stick boss & then the engine build code on the distributor mount pad I should be able to definitively give you the CI

I don’t have access to the 1966 SportVan atm... but the casting # is: 3921968. I don’t have the build date. Is there any reason I can’t just swap, without any accessory changes, to a 250ci, even if what I have is a 230ci?

Easiest and most common swap done!

Don't worry about the codes then...

If its the original engive in your 1st gen, then its a 230. If you drop the pan, you can look at the crank casting number and that will tell you if its a 230 or a 250.

You can make a 230 into a 250 by changing crank and pistons.