I'll be pulling my 460 out in the next 2-3 weeks in order to get it on the stand and replace the rear main seal once and for all, after my failed attempt over the winter doing it from underneath the truck.

Since it's already out and on the stand, several people have suggested I do a rebuild on the thing, at least on the bottom end.

I don't want to sink a ton on cash on it, but the idea of a rebuild to keep it running another 100k or so is a good one, although there are no real issues with the engine in its current condition (other than the rear main).

I've heard everything from "just throw new bearings on" to "bearings and simply re-ring it" to complete rebuild with new oversized pistons, ground crank, the whole works.

What does one face cost-wise for the various rebuild options? What about performance / longevity for each? I know it's not an easy question to answer, but for anyone with experience on the subject, I figure might have something to chime in with.

Last compression check I took, I got roughly 120 psi across each, with one being noticeably low (10-15%?). Keep in mind I'm at 6,000ft elevation so compression numbers are skewed toward the low end. I feel the truck could have more power, but I don't want to spend thousands in the process.

 

Ok, so a basic build that will give you the most longevity is the over bore with the regrou d crank. If you do the assembly yourself, you can expect about 1500. That's budgeting a grand for the kit, and 500 for machine work. I'm basing this off the costs of mine. A basic kit, or rather a stock kit, should run you about $1000. My machine work ran about $500, but I had the shop do all the tear down and assembly on the heads. It will run considerably more if they do the complete engine. We have enough old hats on here to walk you through the build that you should be good on that.

A lot will also depend on the state of the block. When you get it apart, check the ridge at the top of the cylinders. There is a wear limit that will tell you if you need to bore it.

 

Is there an intermediate "re-build" that's not a waste of time? I understand a lot depends on the condition of the block and related components, but I was hoping to spend less than 1,000. That's not to say that I wouldn't spend more if the consensus is that anything in between would be a waste.

$1,500 is a lot to swallow for a truck that will commute one day a week (if that), and take infrequent camping trips in summer, hunting trips in winter. If I can get another 3-4 years of good running without major work, I'd be happy.

 

You can buy Federal Mogul (and other brand) basic rebuild kits that cost like $400 plus or minus. They include the rings, bearings, gaskets, oil pump, timing chain most of the time. Those save a bunch of money. Most kits come with pistons. Check them out. Personally if the engine was in good condition I'd just do a rering and new bearings and have the heads re worked and call it good. Choose your new cam on your own, that'll add a little more to the rebuild but you can choose what you put in there and that is worth the added cost.

 

I personally am not a fan of replacing rings without boring the cylinders... new rings are perfect circles, the bores have become egg-shaped. And, you have to remove the heads, something that isn't necessary for a rear main seal replacement.

If you remove the heads, then I'd bring 'em to a machine shop and have 'em gone through.

New rod bearings are probably a good idea, measure your current journals to see if the crankshaft has been ground down already (so you know what size bearings to get).

In summary... if all you're needing to do is a rear main seal, then new connecting rod bearings are a good idea but leave everything else alone. If you're going to do all this other stuff (cam, heads, etc.) then I vote for a total rebuild, not a half-assed job of it.

 

The engine has never come apart, other than my taking the oil pan off to try and replace the rear main, and changing the timing chain to a straight-up EFI set. The truck had 94k when I bought it a year ago and was all original, smog, A/C, and everything.

 

If it runs good and didn't use any oil, I would not mess with it. I would pull the pan and fix your seal, and I believe I would also pull the front down and change out the timing chain set for one of those early sets everyone talks about. If I have a used engine out I always changed the timing chain set, they like to wear and a lot of them had the plastic coated timing gear that needs to be gotten rid of.

I recommend you look online for a complete engine gasket kit and compare that price to the indvidual gaskets. I am not sure about a 460 but I do know a complete gasket kit for a small chevy is cheaper than buying the individual gaskets and seals that you would need, even though you get head gaskets in the complete set you will not even use.

 

If you want a stock engine just do some minor stuff. Maybe pull the heads and measure the bores to see if its getting out of round. Change crank bearings and maybe have it polished. I mean you are going to be in the bottom end anyway so do a bit of preventative maintenance. If you throw the $1500-$2000 at it you will pretty much have a "new" engine. Something you wont have to worry about for quite a spell. Either way it would probably be a good idea to throw a complete gasket set in it, if one leaks the others can fail at any time.