[hot_rod_kid]

So the other day I picked up what I thought was a 250ci Inline from a 1968 Nova. I get home today to check casting #'s on the block, head, carb, etc to be sure I picked up the right mill. Well, the casting #'s on the side of the block reads 3921967. According to the inliners site , that is the casting for a 1964-69 230ci inline. Now, I dug a little deeper because I wasn't satisfied with that one result and was bound and determined that I had the 250. After further reading, I learned that starting in '68, Chevy started stamping VIN information on the block near the distributor that included the intended application for the motor. Well, underneath a good layer of grease and dirt, I uncovered F0610CM. According to Nova Resource, the intended use of this block is a 250ci that was paired with a 3 speed.

My question is which stamp do I trust without tearing the block apart? I have a feeling this is the 230 block with the 250 rods and pistons, since both the 230/250 have identical bore. Was GM cutting corners and just assembling these blocks differently while using the same casting #'s for both the 230/250?

Anyone who can shed some light on this would be much appreciated. Thanks in advance.

[starnest]

I don't have any documentation on the 6 cyl engines. And for the v-8s even the experts agree that cheverolet's documentation was at times very poor.

There are several v-8 blocks that were used to build multiple displacement engines, both documented and not. It would not be a stretch to expect that they did the same for 6 cyl engines. And since the 230 and 250 share the same bore size, I could see them using that block to build a 250. It could be a regular production occurance, a shortage of 250 blocks and they used your block to meet production, or even a mistake during assembly, where someone used the wrong block. Of course you won't know if it's a 250 until you check the stroke,

[hot_rod_kid]

Originally Posted by starnest

I don't have any documentation on the 6 cyl engines. And for the v-8s even the experts agree that cheverolet's documentation was at times very poor.

There are several v-8 blocks that were used to build multiple displacement engines, both documented and not. It would not be a stretch to expect that they did the same for 6 cyl engines. And since the 230 and 250 share the same bore size, I could see them using that block to build a 250. It could be a regular production occurance, a shortage of 250 blocks and they used your block to meet production, or even a mistake during assembly, where someone used the wrong block. Of course you won't know if it's a 250 until you check the stroke,

That's what I was afraid of. I plan on just dropping this engine in without taking anything apart. I have a friend interested in the 230 for a rat rod project, so the "250" is it's replacement.

[cobalt327]

Originally Posted by hot_rod_kid

That's what I was afraid of. I plan on just dropping this engine in without taking anything apart. I have a friend interested in the 230 for a rat rod project, so the "250" is it's replacement.

I know you had your sights set on a 250, but the little 230 is a decent little mill, too (kinda like a 327 vs. a 350 SBC). I liked the one I had in a '65 PU, not a powerhouse, but reliable as a stone axe.

I say if it's sound, run it! Hopefully it won't have to pull a lot of weight w/highway gears is all...

[hot_rod_kid]

Originally Posted by cobalt327

I know you had your sights set on a 250, but the little 230 is a decent little mill, too (kinda like a 327 vs. a 350 SBC). I liked the one I had in a '65 PU, not a powerhouse, but reliable as a stone axe.

I say if it's sound, run it! Hopefully it won't have to pull a lot of weight w/highway gears is all...

I know, I love my current 230. Aside from the knock, it pushes the boat Belair down the road at a decent clip. With the TH350 behind it, it's a fun cruiser

My plans for the "250" are for the future, mostly. I am swapping it in as is after a scrub down, and plan on running it for a few years until I am on a more dependable income (still in college, few bills yet to pay off) when I can drop some money into it. I hope to give it a mild cam, lump port the heads, run dual 2-barrel carbs with headers. Nothing too drastic.

The 230 on the other hand would be sent to a cool rat rod project my buddy has planned, where it would see a 194 head, street cam, offy 4bl intake, custom made headers, and a blow-by turbo setup. He wants at least 350hp out of it. From what I've read, it's possible. I would be the engine builder on that project.

So does anyone know for sure, or should I just speculate that it is in fact a 250?

[ctandc]

The 230 and 250 blocks were the same (pre-integrated head / intake) from everything I've seen.

Only way to truly know is to yank the head and check the pistons. Supposedly stock 230 pistons were flat tops with valve reliefs, 250 pistons were different.

[cobalt327]

Originally Posted by hot_rod_kid

So does anyone know for sure, or should I just speculate that it is in fact a 250?

I cannot say for sure. There are a few links HERE (towards the bottom of the page under 'Resources') with info on ID'ing/casting numbers that might help.

You can also estimate the stroke of an assembled engine by simply inserting a piece of wire down the spark plug hole, rotate the engine by hand (taking all the spark plugs out helps here) to the bottom of the stroke, mark the wire, rotate to the top of the stroke, mark the wire again. The distance between the two marks is the approximate stroke. It won't be exact, but the difference between a ~3-1/4" and a ~3-1/2" stroke can be seen.

[ctandc]

You might be able to find out what the crank journals should measure on a 250 vs 230 and drop the pan and check it.

[cobalt327]

IIRC the 292 has a different rod journal diameter but the 230 and 250 have the same size journals on the rod and main. I'd be checking the casting numbers and date codes of the block and head to see if that decided it one way or the other. If the casting dates of the head and block are very close to one another and the head c/n says 230, I'd say it was a 230.