I'm currently working on rebuilding a 80s model 4 bolt main 350.I already taken apart the motor to get to clean and replace bearings.My question is the cylinder walls.I feel no rough patches or ridges....but I do see discoloration on the cylinder wall.Is that normal?Its a stock bore block.The engine was taken apart due to a blown headgasket.I lost compression on numerous cylinders. Thanks in advance
That looks an awful lot like rust to me. Whatever it is, it isn't any good for the rebuild. At the very leastI would take it to your machine shop and see what they have to say. You might be able to get away with just a honing and be able to reuse the pistons. Sent from my SM-N910V using The H.A.M.B. mobile app
A couple of them look pretty bad, but I can't rub my finger over it and feel how deep the holes are. I expect a machine shop will tell you it's time for a rebore, and possibly a couple sleeves. That kind of pitting can be deeper than .015", which is all that a normal .030 overbore will clean up. But the number of pits is also important, you can get away with having some. You don't want any significant area rusted away, though, as it will never seal the rings.
If it needs sleeves JUNK IT.. Not worth doing the machine work any more, 350 blocks are getting cheaper since most everyone wants a LS or such. Unless it was numbers matching engine for something special just not worth sleeving IMHO. .030 over bore is standard for a first rebuild though... some will do .010 or .020 but .030 over slugs are cheap.
Those era blocks are thin wall castings and had a lot of core shift. Better off looking for a better block if it needs to be bored. Pat
Man alive... These 350s are cheaper than I thought. Hardly worth the 4 bolt search, and all the 'right stuff'...and the time and $$! If I was 'short a Chevy engine', I'd buy the crate deal. BUT: Is this a 'Hecho en Mexico'? ...or, the 'Goodwrench'?
I'd run a hone through it and see what cleans up or not (no monkey balls). Don't get too carried away, just a light hone to see if it's straight or not. You might get away with just re-ringing it. Why did the head gasket blow? That might tell you the rest of the story.
Clean it up and measure the bores. I’m running a 060 over 350 with zero issues. As far as buying one, why? This is a hot rod site. We build stuff here.
Chevy has not cast or built the 350 in several decades now. There’s 3 basic configurations of it Up to 86 86-96 96-2001 With some variety amongst the 3. If it’s just basic motorvation to go get ice cream on fair weather Sundays it’s the way to go. If it’s for your DD beater with a heater truck to get to work everyday - a new truck is 20 times the cost. If you want something a little snottier it’s not a bad place to start from on your own or you can up the buy in cost and get more power in the package dropped off at your door too. If you want something special then be sure to go see your local machine shop.
What do those spots feel like when you run a fingernail across them? You said you couldn't feel any rough patches or ridges. Earlier today I took the head off of an O/T 650 Yamaha twin, and it had some very similar looking stains, but they are totally smooth even when running a fingernail over them. I believe they were caused by some condensation which would have eventually caused the motor to stick, but I got to it before that could happen. I'm just going to run a hone through the cylinders and re-ring it.
10067353 part number on a new crate engine. I would not hesitate to have it bored out, but if the heads need anything more than a basic valve job, it’s more cost effective to replace it. Sent from my iPhone using The H.A.M.B. mobile app
I'm running a '73 4-bolt, 010 block that's .060" over with a 3.75" stroker and have no issues either. But it might be different for an 80's block. Do your homework... you might want to sonic test it. I got mine for the price of machining.
Sure they do...in Mexico. They are not production engines installed in any vehicle, but they still make and sell them over the counter.
I've honed a few in that shape and stuck cast rings in them with no issues. Was it the correct way? Probably not, but they were all just drivers
Have an engine guy look at it, you really should get it cleaned up if you want to rebuild it. All standard rebuild stuff. If you have a hone handy, give it a few swipes to see if it cleans up.
I went the crate engine for my 48 because the Chevy blocks are only .100 thick after a .030 bore job and I had one crack down the cylinder wall. Unless you can rebuild the engine yourself, I found that a rebuild costs double of what a crate engine costs and its all brand new stuff. JMO
Run a hone thru it. Use a straight edge to check the deck to be certain its flat. If it looks good afterward. Measure the top and bottom of the bore. It its not too worn. Just buy a $100 ring overhaul kit and put it back together. I reringed a 350 taken from a 70 caprice Twenty seven years ago. That engine has been in a 77 GMC truck. A70 Chevelle and a 67 GMC pickup and is now in a 70 chevy pickup. Still runs strong however its beginning to have a bit of blow by. A little more puff back than the PCV can handle at High RPM. If driven reasonably it doesn't use oil.
Like said above, it depends on what it goes in and what kind of service you expect. Know that machine shops are there to do machine work and make money. They are going to want to make a new motor out of it, not repair it. I agree with Cast Iron Rings. They really are forgiving and it's a Cheep fix. Remember that part, "a Cheep Fix" but often a just fine thing to do.
I've done a few engine overhauls/ring jobs recently that had rust in the bores. Some worked ok, others did not. It is really hard to tell from a picture, or even a description, how bad the rust is. I guess you can try it and learn, or have others who are more experienced look at it and offer their advice. Good luck...
Yes try to find a machine shop that will Knurl pistons. Or polish a crank rather than turn it down. Or lap the valves rather than grind the heck out of them. Ive has more problems with stuff that machine shops worked on than old well worn junk that I patched up. And nothing you get back from a machine shop is ever clean enough for me to install.
Of course not, you ALWAYS have to clean parts before assembling them. Labor rates have gone up faster than parts prices, so it's not surprising that machine shops no longer do work that will save old parts. There's no demand. Also, this is why complete replacement engines are so popular now.
The 307 that's in my 57 dump truck. Ran all summer in a stock car without a air filter. It was really smoking and had way too much wear. I installed .020 oversize rings and filed the end gaps to fit the worn bores. Ifixed the carb where it only opens about two thirds. locked the rear end in low range. And rented it to a construction outfit to move dirt and stuff on the job site. The single axle got around good and worked great. Still runs good and don't smoke.
Thank you for the responses. The motor was run without coolant one day unfortunately and it overheated.The pistons,bearings and crankshaft all appear clean and I dont see anything out of the ordinary.This is going in a 55 Chevy pickup that will be a crusier.It may see 1000 miles a year if that Sent from my SM-N960U using The H.A.M.B. mobile app
My Dad had two terms he used, Overhaul and Rebuild. Once you understand what you expect once done then you know what one to do. This statement tells me you only need and Overhaul not a Rebuild unless your Wallet has no limits.
I agree with squirrel....... Since you are asking this question, I would think this is a good opportunity to learn from experience. If you go buy a crate engine, thats probably the cheapest way to go for the long run. It will get you a good basic ......but low performance engine.......but you won't learn much. On the other hand, if you take this engine which you already have and at least begin the process to rebuild it, you gain some experience that will last a lifetime. First I would check to see why the engine blew head gaskets or possibly cracked a head or block. Then I would measure the diameter of the bores top/middle/bottom with an inside micrometer. Good excuse to buy some inexpensive ones. Then clean the block and sonic test the cylinder walls to see how thick they are. You can have it done or they have some inexpensive testers you can buy online. Then you again have something you can use forever. At that point you should know whether the block is usable and if you need to bore or hone. We can speculate on the HAMB till doomsday, but actually measuring is the only way to tell for sure. When you have more info, we can offer more speculation about how/if you should proceed. There is a lot you can learn by building your own engine, and you can take pride in the fact that YOU did it. You can also tailor the engine with the pistons and cam of your choice. Might even put an inexpensive 383 stroker kit in it. In the long run it will probably cost you more money, but how much is experience worth ?
Yup. ^^^^^^^ I do not know about current castings but in the past Mexican blocks had a higher Nickel content than American blocks. As for the block in question if you want to build a 350 and actually drive it normally a .030 overbore is common and I have hawged them out to .060 with good success. Do yourself a favor and go back in with plasma-moly rings. They are the modern equivalent to Chrome rings and are not nearly as hard on the block as cast iron rings.
You can do a DIY the whole way and it will probably run fine for general use. Get it fairly clean, borrow a dial bore gauge... tall order.. or use telescoping gauges and a micrometer will be close enough to see how much taper it has. Years back there were overhaul re-ring kits to use on out of round and tapered cylinders, not sure if they are as popular today. The rings were softer to allow them to break-in on funky cylinder surfaces. Measure up the crank, clean it good and you can polish it yourself. You need to carefully look at the pistons for scuff and abnormal wear. Any service that is over your head, an engine shop can do for you. Order an overhaul kit, Summit or other parts house, hone the cylinders, clean everything (brush sets are available at HF) and put it together.
I can tell from the crosshatch that it probably does not have any significant taper. What I can't tell, is the test that was mentioned about if your fingernail will hang up in any of the rust pits. I have a block that looks a lot like that, same thing happened to it, before I got it. After running a hone through the bores, and inspecting it, I decided it would probably need either an overbore or sleeve to fix at least one cylinder well enough to make it worth the effort of putting it back together. But it's hard to tell exactly from pictures.
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