250 six banger- repair/replace, or?

[68isgreat]

After getting this rusty 68 short stepside recently, with the original 250 six and 4 speed, I put about $600 into replacing all the tertiary engine parts to get it running. New distributor, coil, wires, plugs, alternator, fuel pump, carb, etc (not shown in the pic below). I got it to run, but it was really rough, with white smoke out the exhaust, and would barely idle. Original 4 speed works great though. Checked the dipstick and the new oil looks like chocolate milk, so I'm assuming that's a blown head gasket. Not sure what route to take next. I could just put a new gasket kit in it, but who knows what shape the bearings are in, etc. Or, $2k for a full rebuild, which would keep it original. Or, $500 for a used motor, but who knows what problems it would have. Or, $2k would get a nice used small block, but then you need new exhaust, not sure if the motor mounts need changing, etc. etc. Heck, I've even thought of putting an electric motor in it, since it's just going to be an in town rig, but that gets spendy in a hurry also.

I'm leaning towards rebuilding the original six. They are great motors when running well. For those of you who have been down this road before, what do you think? Good idea? Bad idea? I'll be taking the front clip off soon so I can start work on the cleaning up the frame, which will make engine removal much easier also.



p.s. - you'll note in the above photo that whoever put these wires in has the firing order wrong. Yes, I changed it to the correct 153624 firing order, made sure the rotor pointed to #1 at tdc compression stroke, etc.

[72SB]

If you could find a good used small block, thats what I would do. You would spend as much if not more rebuilding the 250. For the rebuild you are looking at .030 overbore, pistons, bearings, crank polish or .010 grind, headwork, etc and end the end its just a good running 6 but not much power

Yeah there will be some "oh by the way" for the inline to V8 swap (engine stands/mounts, fan/shroud, exhaust) but the V8 will otherwise bolt in.

I also have a 250 in my 72. If it didn't run so well I would put a crate motor, V8, in it

[dagnabbitt]

I'd leave a good running six right where it is, but it sounds like yours is not running good.

I'd find another six that is running nicely and swap them. Lots of people don't want them and you can find them cheap. Maybe even a 292.

Then you can re use those parts you have purchased for this engine, if necessary. Or rebuild it in your spare time, if you have any.

[68isgreat]

Originally Posted by dagnabbitt

I'd leave a good running six right where it is, but it sounds like yours is not running good.

I'd find another six that is running nicely and swap them. Lots of people don't want them and you can find them cheap. Maybe even a 292.

Then you can re use those parts you have purchased for this engine, if necessary. Or rebuild it in your spare time, if you have any.

Thanks guys. Finding a six that runs good is the challenge. From a cost standpoint , that definitely makes the most sense, especially since I can use the new parts I've already bought. I don't really care that much about power either. It's just an around town rig, with occasional trips to the wine country and art shows once it's fixed up.

[Rust_never_sleeps]

Sixes are pretty resilient, so maybe just do the head gasket and see if you can drive her for a while. Meanwhile you scout for a replacement you can rebuild yourself in your "free time" ;-)
I love the six, but if you have to drop ~equal cash on a rebuild, it's hard not to go with sbc

[68isgreat]

Originally Posted by Rust_never_sleeps

Sixes are pretty resilient, so maybe just do the head gasket and see if you can drive her for a while. Meanwhile you scout for a replacement you can rebuild yourself in your "free time" ;-)
I love the six, but if you have to drop ~equal cash on a rebuild, it's hard not to go with sbc

Definitely agree!

[72SB]

if the 250 has never been rebuilt and has over 100k mi on it, it needs a rebuild. If you just pull the head to replace head gasket, at least lap valves and put in hardened exhaust seats. A compression test now might sway OP one way or the other pending results

I was offered $1k for my 250 with 3 speed and guy would do the labor to pull it as he wants to drop it into a project of his. It just runs so sweet I can't pull the trigger but if my 250 had the issues OP's has, I would just buy a SBC....or rebuild a 327 I took out of my 67 Camaro

If its just a cruiser, the 250 is fine.

[HO455]

If you're not sure do some investigating. Pull the head and determineif the head gasket is actually the issue. Inspect the bores for wear and mic them.

While the water and oil are out drop the pan and inspect the oil pump plate and pull a main cap and inspect the lower half of the bearing. You may find nothing seriously wrong and the you can reassemble the engine and run it with out worries and you've only invested your time if it doesn't pan out to run the engine with some simple repairs.

Good luck and let us know what you find.

[truckster]

55 years is a lot of unknown history. I'd want to know the condition of the engine a little better before I made a decision. While the chocolate milk oil shows there's water in the oil, a head gasket is only one possibility. If you want to keep it, I'd tear it down and have a reputable machine shop go over all the components you plan to reuse. I've had cracked blocks that didn't become obvious until they were boiled.

Or... just slap a head gasket on it and see what happens.

[68isgreat]

You guys are all making a lot of sense. Thank you. I'll let ou know what I find. Would be great if it's just old gaskets.

[factorystock]

Originally Posted by truckster

I've had cracked blocks that didn't become obvious until they were boiled.

Very good point. All Chevy 6's after '62 and all V8's are "thin wall casting".
Hairline cracks in blocks are just as common as blown head gaskets. I would look for a recently rebuilt six that somebody replaced with a V8.

[cj847]

Just run a quick compression check. It will tell you which cylinder(s) have a problem. But, also will tell you the condition of your "good" cylinders.