I thought for my 2000th post, I'd put up a good set of questions. Even officer Dep will accept this one in tech, I think.

I posted earlier that I bought a 73 with a bad engine. i picked up a replacement engine fairly cheep with some pretty good components and credentials. It's a 70 350/300. It had been sitting for a while but turned over and was (at least recently) stored indoors. I thought it was a good risk.

I took it apart this weekend to see what's what. it's raining here so time for indoor work. Here's what i found.







Before you say anything, these are "after" pictures. I've been cleaning this cylinder for about an hour. Although a few of the bores show some water signs, this one is by far the worst. You can just barely see in the second picture that there is a rust ridge.

Most of this looks like it'll come off with aggressive cleaning. I'm using paper towels and transmission fluid on most of it and steel wool on the rust ridge.

Question is, what next? The intent of this engine was to tide me over until next winter by which time my new motor would be ready. I really don't want to sink a ton of money into this one, but i also don't want it to billow smoke, spit fire and blow up either.

A) Should I just clean it well and hope for the best?

B) Should I pull it apart and replace the rings and bearings? If B then would a cross hatching be in order?

C) Should I break down and have it bored?

The engine looks to have been bored very recently. There is no ridge whatsoever and only minimal carbon on the piston crowns. Nice, tight seal too. The oil that I poured into each bore yesterday is still sitting there.

While I have your attention, two additional and less important questions.

As you can see from the first pic, the engine builder loved blue Permatex. How do I get this off? Is a razor blade scraper a bad idea on the block on a mating surface? I was also thinking of using Goof Off, but it's on REALLY thick.

Second, can anone identify the piston? I assume that it is aftermarket because of the directional notch, but certainly don't know.

 

I can tell you that the blue on the deck of the block is NOT permatex. It is from a teflon coated head gasket. Should come off with a single edge razor blade.

You certainly need to take the lower end apart for inspection and see what type of water damage you have down below.

How bad is the pitting in the cyl bores? Can you use a flex-hone on the bores and remove the rust?

Seems like a lot of work for an engine that is just going to see less than 12 mo of service. Wouldn't you rather take the cash and upgrade something else on the car?

Just my thoughts.

Bob

 

Those pits are too deep for honing. I think it's more trouble than it's worth for 1 season.

 

Could probably sleeve the cylinders.

 

Just for a year huh. I'd disassemble it & take it to car wash, then hone the bores & use an oversize ring. I'd have the crank polished or turned, if needed, and install new bearings (cheap insurance). Add new cam bearings, freeze plugs & oil pump. I'd clean up the heads & put on some mushroom valve seals. Throw it together & fire it up.

 

You can get a smallblock re-ring kit with cast iron rings, bearings and complete Felpro gaskets for anywhere from 60.00 to 100 bucks. Some extra add ons may include brass freeze plugs etc.

If you do anything past this, you may as well go for a real engine build.

I would gently hone the bores with a tapered hone just to eliminate the ridge and the protruding rust, not the pits. When the hone marks on the ridge start to merge with the rest of the bore, stop. You will see the ridge after you start. Then take a ball hone and get the crosshatch, trying to remove as little as possible. At this time you will see how bad the rust pitting is and make your decision to continue.

Then relap the valves by hand new umbrella seals, and general cleanup.
A double row timing set is cheap and worth it.

I've done several engines this way over the years and the result is predictable. In the worst case, they may burn a little oil between oil changes, but they won't smoke. In my case, they usually last at least 30,000 miles.

If your intent is truly till next winter, then this is an option, but don't consider it a rebuild.

 

This option is about as far as I'd want to go with this motor. If I go through the trouble of any machining, I'd put in a stroker kit and possibly keep it for a while. One of the reasons that I don't want to do this is the amount of time machining seems to take around here.

I did a little more cleaning and the pitting doesn't seem to be all that bad, though it is very hard to measure. Besides the bearings, which I'll have to take a look at, I'm concerned about the rings. The pistons must be aluminum as there is no rust or corrosion visible, but the rings certainly won't be.

 

A bit of an update and an interesting twist too. I spent a little time cleaning the rust last night and most of the ridge came off. Looks like soaking in oil and tranny fluid softened it up. I don't have pics yet but most of the rust is cleared. I borrowed some measuring tools from work to verify the overbore (+ 030 as expected) and also a bore dial indicator. It's a little hard to be accurate because of the needle bounce, but I would estimate that the worst pits are less than 0.0005 inches.

What's reasonable/acceptable? At some point these will do less damaging than honing will. Regardless, I'll have to check the bearings before moving forward.

 

You want a little hatching and I don't see any in the pics, but I'm not there either.

I would say your back to this

You don't have to remove material in the bore, just scratch it up a bit.