What needs to be done to a Chevy 194 to get it to 250 inches? Rebore & pistons? Rods? Any other modifications required? If I go down this road, any U.S. sellers that specialize in these engines?
Out on a limb here, but guessing if possible longer stroke crankshaft, etc. I don’t believe just an over bore will get you there Maybe search on bore x stroke specs for each
you're not going to be able to bore that block 5/16" bigger.... If you want the big engine, start with the big engine. sorry. I know they're probably hard to find down there.
Squirrel is right on the mark.. Pick up a nice 454, get one with low compression from the 70s clean it up, change the timing chain, check the cam, rings and cyls..
The 194" was unique with a 3-9/16" bore and 3-1/4" stroke, forged crank.. The 230" had a 3-7/8" bore and 3-1/4" stroke, forged crank. The 250" shared the same block configuration as the 230" but with a 3-17/32" stroke, fully counterweighted cast crank. https://en.wikipedia.org/wiki/Chevrolet_straight-6_engine#194_2
I don't think you can get there from here with the 194 block. The photo and pfd below are a scan of the basic specs such as bore and stroke on 194 Through 292 sixes. The pfd might be easier to read. The differences between bore and stroke between the 194 and 250 are quite a bit My 4 barrel intake for my 292 came from Aussie speed and as they make a ton of stuff for that series of engines from 194 to 292 I'd have to think you can find larger size Chevy design sixes in Oz reasonably easy. Dang, that cost me some money as I just ordered the plenum Pig for my intake after chatting to the online rep from those guys. I've been hunting that piece for a while. If you were close I have a well worn 250 in my 48 that you could have for pulling it out and hauling it off. It's so worn out that it didn't have enough compression to start to drive home the last time I drove it. but it should be a builder.
What about a 292? [you will need to stagger an engine mount] https://www.gumtree.com.au/s-ad/lin...nsmission/chevrolet-6-cylinder-292/1260043725
The family of the 194, 215 (only used in Old's and Pont's instead of the 194 engine), 230, 250, and 292's; that's 5 engines to choose from, so you "should" be able to find something down there. And the age old rule still applies, "there's no substitute for cubic inches", so start with as big as you can to begin with. The 194 head, # 3864883, is a good addition to a Street 250, that has dished pistons, in order to raise the CR with it's smaller combustion chambers. Also has smaller ports to aid in down low torque. Get yourself a Clifford "6 = 8" catalog, spend some money, and have fun!!! I am Butch/56sedandelivery.
They were used in boats. Check marine salvage yards. Mercruiser 150 is 230 cid, 160-165 is 250 cid, 200 is 292 cid. Also may come with cool finned valve and side covers.
I remember a magazine article way back when, where they took a 292 crank and offset ground the rod journals to 230/250 size and bored a 230/250 block .030 over to come up with 308 CID. Don't remember any other details.
The 292 crank in a 250 block can be done but it takes some serious parts sorting to do it. .590 Is a lot of difference in stroke though. My 48 had a 194 in it when I bought it in 1973 and I put some miles on that little bugger before it used more oil than gas. Nice reliable and trouble free little engines that do pretty well in a light car but getting any real performance out of one would be a real challenge. A guy wants to save the head though as it has a higher compression ratio than the larger engines.