Quick backstory:
I purchased a 1965 Dodge A100 camper van last May. It has a 225 mated to a A-727 via adapter plate and it hadn't run in a year. The slant looked rough but I got it running with little effort despite it's appearance. Once it fired up an epic, black backfire blew about 5 pounds of carbon out the tailpipe all over my garage—that set off some alarms. I performed a compression & vacuum test and both were good. I decided to pressure test the cooling system because it was low on coolant and the radiator and hoses looked tired. It had a slow leak but not to the exterior. After pulling the plugs I found coolant on top of the #5 piston. No big deal, I had already planned on pulling the slant and going through it.

Currently:
Last week I got around to pulling the 225 and A-727 out of my van for an inspection and overhaul. After a brief cluster-cuss with a 3-wheeled engine stand, followed by the appropriation of a wide-leg, 2,000 lb. engine stand, I stripped the engine down to see what its ailments were. What I discovered was not exactly on my radar…

The head gasket looked fine. All cylinders had nice witness marks around them. The #5 cylinder was nice and steam-cleaned which made it easier to check the combustion chamber for cracks—I heard these can crack between the intake and exhaust valve seats, and for a moment I thought that might have been my problem, but if so, it wasn’t my only problem.

After obsessing over the cylinder head I finally took a peak inside the cylinder bore and the writing was on the wall, literally. The coolant leaking into the #5 cylinder was coming from a crack at the ring line at the top of the piston stroke on the left side of the cylinder. It was quite clear and not new. There was a stain on the cylinder wall above the piston, at the bottom of the stroke, from water pooling on top of the piston, on the opposite side of the bore coinciding with the 30º slant. #4 and #3 cylinders are also beginning to do crack in the same exact place as #5; their cracks just haven't reached the water jacket yet. I had my diagnosis: worst case scenario.

The engine had been bored 0.040" over at some point and the cylinders didn’t have much of a ring ridge. The oil was a bit milky/sludgy in some nooks and crannies so there had definitely been some history of water intrusion. The inside of the the water jacket was ultra rusty, crusty, and full of rust debris and muck—the worst I’ve ever seen. The engine had clearly been neglected and maintained by someone who was not very mechanically inclined: the thermostat was installed backwards, the short heater hose between the cylinder head to the water pump was too long and kinked shut in the middle (seriously), and the spark plugs still had their crush washers on them within the spark plug tubes—I guess I shouldn't be too surprised.

Another red flag was the aftermarket, over-sized flex fan. I say over-sized because the bottom of the radiator tank had been in contact with the fan (but not punctured) as well as the radiator support behind the radiator, in front of the fan. The support had been clearanced after the fact because the fan was all beat up from contacting the radiator support and the radiator tank. Additionally, the exhaust manifold had cracked and become a 2-piece unit. The cylinder head gasket, intake & exhaust gasket, thermostat housing gasket and water pump had all been replaced at some point in the not-too-distant past. I'm guessing overheating must have been a long-term issue.

The bright side is there's some good parts to be salvaged from the slant, just not the most important part. The crank is a forged crank. The rocker assembly, cam, lifters and pushrods all look good. The Holley 1920 carburetor was a professionally rebuilt unit aaaaand… that’s about it.

The good news is I’ve got a bead on a rebuilt 225 in my neck of the woods. We’ll see if that has a positive outcome.

I really love the van and I'm stoked on these Slant 6's despite my experience thus far. This is my first Slant 6 and it was one of the van's selling points for me.
I was talking to my dad about this situation yesterday and he was like, 'why don't you just drop a 440 in there?' Ha! Blasphemy!

_________________
The Cast Iron Philosopher (Ryan)
I am the Mechanic and my intentions are good.

One person's idea of rebuilt" is not the same as another's.
In addition to the parts mentioned I'd keep that head ( unless you do find a real problem there) as well as those 40-over pistons and their rods.

I hear ya. I'm not comfortable with anything unless I did the work. Hopefully something better will present itself.

And I do intend on keeping those parts. I'd have to magnaflux the head to be sure it's good but it doesn't look as rough as the block. I'm stripping the rest of the good parts off of the engine today. I'll be squirreling away everything until my situation is resolved.

I've already purchased a ton of brand new and NOS replacement parts such as:

Rebuilt Harmonic Balancer (I just got it back from Damper Doc)
Distributor Cap, Rotor, Coil, Points, Condenser, Vacuum Module, Spark Plugs and Ignition Wires
Timing Chain Set
Oil Pump
Complete FEL-PRO Engine Gasket Set
Water Pump
Motor Mounts
New Exhaust Manifold
NOS Holley 1920 Carburetor & rebuild kit
Temp Sender
Thermostat
Oil, Air & Fuel Filters
Rebuilt Alternator
Stock Fan
Fuel Pump
New Aluminum Radiator from FSR
Radiator & Heater Hoses
(4) Cans of Dupli-Color Engine Enamel...

I was ready to get rolling on this thing. But it's okay... everything will work itself out.

_________________
The Cast Iron Philosopher (Ryan)
I am the Mechanic and my intentions are good.