In some respects, the $4000.00 for the engine rebuild sounds a little high, but in many respects it might not be. What can you get for that much money would depend on who does the actual machine work (probably NOT the shop you took it to, but hopefully a competent machine shop) and just what they intend to put on the list of things to replace or refurbish. For a reference point, check on a reman engine from AER (the Ford OEM engine reman supplier, which also probably does the similar AC-Delco reman engines) and NOT a cut-rate "used car lot-type" engine reman company--but you'll probably have to look at a 440 instead of a 413.
From what I've seen by hanging around a good engine machinist for many years, there are some things that you might consider to be saveable that really are on the outer edge of specs, even though the engine runs acceptably well.
First thing, most any engine will need an .030" overbore just to clean things up and get some fresh metal. I've seen some 440s that have very little ring ridge at 100,000 miles, so that's possible, but I suspect that if you mike the bore and check the piston clearance, it'll be on the borderline. True, Chrysler "set 'em up tight" for long life, but that doesn't mean they didn't wear. So, figure on OEM spec pistons of some kind. Going to anything else is not needed in any reasonably stock motor for normal use (or even some racing every so often too).
Second, replacing the crankshaft seems a little "over the top", for sure. Usually, the crank can be polished or, if necessary, turned down .010" for good measure--forged or cast, either way. Key thing is that it's straight and the bearing clearances are in Chrysler's specs. Don't forget to check the roundness of the big end of the connecting rods too! They might need some attention for good measure, or some reman rods from TRW or similar. Or, just don't mess with them--your judgment call.
Third, the block needs to be bored with some kind of high quality boring bar mechnism. Prior to that, they might true up the block by "decking" it to make sure the resulting deck surfaces are level and straight, using the crankshaft for the reference point in the machine. Then, using a power hone machine (AND someone that knows how to read the load meter!) with a competent operator. For that extra bit of finesse, boring the engine on a similar boring machine and using deck plates to simulate the forces on the block when the heads are bolted on can be done plus running 180 degree water through the block while all that's being done.
Using the power hone machine is preferable to doing it by hand, for many reasons, the least of which is the finish hone pattern on the cylinder wall. But it's easy for the operator to end up with cylinders that are bigger in one area than another if they don't know what they are doing, or don't let the block cool sufficiently between honing operations.
These items are some of the most critical operations and should NOT be rushed through. They are somewhat time consuming and a quality machinist is not nearly worth what he might be paid, compared to other machinist jobs.
Or, you can do the "shade tree overhaul" where you just pull the engine down and re-ring and re-bearing it and take your chances. If the cylinders are not too worn, putting some moly rings on the existing cylinder walls (already worn slick and NOT dingleberry honed) have been known to work well in seasoned engines. Just be sure to put the pistons back in the holes they came out of.
Then there are the cylinder heads. Putting hard seats in used to be about $200.00 by itself (about 10 years ago), but that's a judgment call as to whether or not to do that. Then there is reconditioning the valve guides (I'd recommend the bronze helicoil guide inserts as they make a great wear interface with chrome stemmed valves), plus the resultant valve job. The valve springs will need to be checked for tension and shimmed/replaced as deemed necessary. Worn rocker arm shafts might need to be replaced too, as might some rocker arms (making sure to torque them correctly per Chrysler instructions so they don't crack or break--if applicable to the earlier engines).
The whole set of valves would not need to be replaced unless they exhibit a wear pattern on the stem/guide interface area that results in excessive guide clearance when reassembled. A good machinist can make that determination as they usually know what they are looking at. A used valve can be refaced (on an appropriate grinder) many times, but the key issue is the stem wear. My machine shop associate used to have an intake valve from a non-Chrysler motor that was deteriorated down to a pencil-lead-thick stem, yet the motor still ran.
The cylinder heads will probably need to be surfaced too. For this operation, a lathe is better than a "rotatiing rock" and, once again, the person doing this needs to know what they are doing.
One last thing would be having the engine vatted. That requires full disassembly and letting it soak overnight in the hot vat (or cold vat, depending on what the shop has). This will get all of the accumulations out of the engine, plus it'll need new cam bearings and core/freeze plugs when it's done too. This is one of the first things done in the rebuild process.
While there might be some personal preferences on what rings to use, although I have my own personal preferences from what I've seen over the years, the basic decision rule on rings, bearings, gaskets, and such would be "Chrysler OEM-spec quality items OR BETTER". There are lots of inexpensive gasket sets out there and you typically get what you pay for. The ONE exception to that is the name brand "rebuilder kits" that have Fel-Pro or similar premium gaskets/seals in them, but come in a white box and are less expensive than what you can get them for otherwise. Same with bearings and rings too. This is where knowing a good machinist that knows about these things and can get them comes in very handy. That same machinist, like a good doctor of humans, should know what is good stuff and what is not, even within the name brands too. End result, you have good parts in an engine that's got great machine work done to it and is assembled with knowledge
and care.
Pistons can be a little less critical, but as long as it's a reputable brand of cast piston that matches the stock piston in application, they should be ok. In this era of lower octane fuels and rising prices, you might consider using a truck motor piston, provided the resulting compression ratio would not be below about 9.00 to 1.
Then, if you have a fresh engine, you will also need to consider a new (or a reman) water pump, oil pump, fuel pump,belts, hoses, and other similar wear items being replaced at the same time. Spark plugs, plug wires, reman alternator (?), freshened distributor and maybe a carb rebuild after you get it running again.
By the time you're through with all of that stuff, it could well be $4000.00 in expenses. But wait, there's more (as a television journalist on "AutoWeek" always says) . . . what about cleaning up the engine compartment and all of the items that bolt to the engine? Extra time, labor, cleaner, and a little paint. Then there's "R&R" labor too.
As for knowing what's inside of the engine you get back? That's where the integrity of the shops involved comes in. The downside is that if someone did put some flaky stuff inside, you would not know it for 30,000 miles or so anyway, so knowing and being able to trust who does the machine work is important. Same way with automatic transmission rebuilds too. In some areas, it's better to buy "brand name" than take pot luck, although many have had good luck going the pot luck direction.
I know, in the prior times, none of that fancy machine work was done. You just pulled the engine out, took it apart for a looksee, check the dimensions on the pistons, bores, bearings, ordered what you needed (usually "standard"), and put it all back together. Many times it worked acceptably well and still cost a good bit of money, but having it "like new" with at least 100,000 mile durability before it would need any attention was not considered back then.
The one last consideration is finding someone that has some "feeling" for the older vehicles and would take sufficient care in working on them PLUS making sure it was done correctly. As the retired mechanics are dwindling in numbers, whether by age or other considerations, finding someone in their 50s or 60s that still does work on those cars can be a challenge. There can be some younger people that could do a great job, but they might not know all of the little ins and outs of working on older Imperials, much less a Chrysler vehicle in general. This is where networking with some Chrysler enthusiasts in your area might come in handy and be beneficial. If these guys know where competent machine shops and repair shops to do the work are, they are not going to be cheap anyway, but at least you can find some other options that you might not have had before, BUT they might not be near where you are. In addition to this group, there are
also Walter P. Chrysler Club people, a couple of Chrysler 300 club groups, general Mopar clubs that might have recommendations.
Sure, you could buy another car with a "good" engine and swap them. Just be cognizant that what one person classifies as "good" might not be YOUR classification as "good". End result, you could well end up with another worn engine just as you already have, PLUS a parts car to deal with (keeping the neighbors and such at bay in the process, possibly).
I've mentioned a lot of information here and appreciate your time in working through it with me. If you have other concerns, you can email me off group.
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