GM 1968 230 Block vs 1977 250 Block

Posted by: Rjonah

GM 1968 230 Block vs 1977 250 Block - 11/06/17 12:51 PM

I have looked far and near for the answer...

I presume that the GM 230ci and 250ci blocks are the same. I have a 1977 Camaro with a 250 which has 200K miles on it. Still runs. I have a 1968 230 engine with unknown mileage but the bores measure close to the same. Boring is in the future of either block.

I have a crank, rods, pistons, cam, bearings, et. al. for a 250 to rebuild a shortblock. I already have the head, manifolds, carbs, etc. ready to top it off with.

My question is, all other things being equal, is there advantage e.g better metallurgy, casting, design, etc. of using one block (1968 vs 1977) over the other?

1) If there is no difference, I will leave the 250 in the Camaro and build the 230 into a 250.

2) If the 250 is a better block, I will pull it, build it and replace it.

3) If the differences are negligible, refer to number 1.

Thanks in Advance,
RJ
Posted by: stock49

Re: GM 1968 230 Block vs 1977 250 Block - 11/06/17 05:54 PM

Originally Posted By: Rjonah
My question is, all other things being equal, is there advantage e.g better metallurgy, casting, design, etc. of using one block (1968 vs 1977) over the other?


The 230/250 blocks are the same in terms of dimensions - i.e. 3.875" bore. The added displacement comes from .28 additional stroke.

From my perspective - when dealing with blocks that are 40 to 50+ years old - it comes down to the individual block's potential not the age difference. Does the block magnaflux crack free? Given it mags OK, then how much room is left for boring/honing to true? If a particular block exhibits cast shifting then the less the over bore the better . . .

Whether the herd of '68 blocks is somehow better/inferior to the herd of '77 blocks seems irrelevant in my mind. You have two from which to choose from in your garage . . .

Posted by: Rjonah

Re: GM 1968 230 Block vs 1977 250 Block - 11/07/17 12:14 AM

Hi Stock49,

Thanks for your response. If there were no improvements, in material or design, made between 68 and 77 in the manufacturing of the blocks, I will undoubtedly disassemble the block not in the running vehicle (the 68 block) and verify it is a good candidate for the rebuild.

It is the simplest route since I get to continue to drive the vehicle whilst building the new engine.


BTW, an example of a difference in design and manufacturing. 68 230/250 heads ok...77 integral heads not so much. But that example is easily identified.

Thanks,
RJ