I bought a used 250 for the Wife's 62 Nova wagon and I finally got around to pulling the head off to get a look at the cylinders. I am trying to determine if the it needs to be honed, rebuilt or good to run. What do you guys think? Here are a few pics of the clyinders. In order of the pics #1 Looks like there is a scratch in the cylinder wall. #2 #4 on left and #3 on right #6 on left and #5 on right
Hard thing is deciding where to stop. If you hone it you might as well do rings. If you got it down that far you might as well polish the crank and slide in a new set of bearings. If you go that far then you might as well do a valve job. On and on. But to answer your question from what it looks like in the pic's it probably could use a hone job.
I agree with Tman, internet pictures are hard to interpret. I've never seen a crack propigate along the circumfance of a cylinder...but there is also no reason for there to be a scratch in that direction; usually, scratches are in the same direction as piston travel. Ok, I just saw the bigger pictures. To me, it looks like pitting. The motor may have sat for some length of time with this #1 exhaust valve open. This would allow water vapor to enter the cylinder from the exhaust port, condense, and accumulate on the top ring. As for rebuild, re-ring, hone or whatever...was the motor running recently? If so, did it run OK? One good indicator of wear is cylinder glaze. From the pictures, it looks like the cylinders are fairly glazed and no hone marks remain. This meens that the rings and cylinders have worn each other down and won't seal as well as when they were new. However, that doesn't mean it won't be a good motor for your wife's grocery getter. I think a lot of people, on this board and in general, would be very suprised if they opened up thier motors and saw the condition of the internals. I've seen some great running motors that looked terrible on the inside. In it's time on this earth, that #1 cylinder on your 250 has undoubtedly seen BILLIONS of violent explosions, extreme heat, pressure, metal shavings, dirt and lots of other stuff and it has lasted this long. If it were my motor, I'd put it in and run it until there is a reason to rebuild it. 250's are notoriously rugged and robust motors with extremely long lives. If you are inquisitive and just want to know, I suggest buying/borrowing a bore guage. Scrape the carbon ring at the top and measure the cylinder bore at the top, then rotate the crank and measure the bore as close to the bottom as you can get. There will likely be some cylinder taper, but I think most Chiltons or Motors manuals will tell the allowable cylinder taper. Good luck dude.
#1 looks like a broken ring and a piece is trapped in the piston groove. You will probably find the piston damaged. The vertical scratches are made by chips from the broken ring.
Thank you all for the input. I bought the engine used and the guy I bought it from said it ran when it was pulled. But we have all heard that before haven't we. The thought of having a broken ring and piston scares me a bit. I think I may pull the pan and pull out the piston on #1 and inspect it for damage. If everything looks OK I will check the taper like drgnwgn289 suggested. If everything looks OK, I will put in new oil pump fuel pump, cam (want to match the Clifford manifold and header I already have on the 194 that is in the Nova already) and run it. What is the worse thing that could happen? I have to put the 194 back in? I am looking at putting in the 250 for a little more power and to better match the performance parts I already have. Hopefully will have more info over the weekend.
if you are going to all the trouble of new cam oil pump and pick up, performence intake, new timing gears are you sure you want to use it as is. i bet you will find the cyl has some taper and slop at the top, well i at least i am never lucky enought to find one that doesn't. i think i have read you can use 307 flat top pistons in a 250 if you need to go .030 or .040 over. i think you can also use the 194 head for a little more compression as well.i think everyone is right it will prob run fine, but do you want to put that many aftermarket parts and upgrades on a iffy motor? good luck on whatever you do though.
I have to think I would have checked the compression first and not worried about what I didn't see, but now that you're this far, best make sure there's no ring damage on the #1 where the scratches are. 250s are so common and cheap I'd almost buy one I could see run before I rebuilt one, unless budget was no option and I wanted to be 100% sure of the thing without the trial and error of running it for a while and maybe find out the hard way there's trouble. But I'm sure it will run like that. Guy I knew who went to the same school a couple years ahead of me told me how the one instructor liked to take older cars that ran and drain the oil and see how long they lasted. While he was there the guy did this with like a '77 Nova with a 250. He said they drained the oil out, it ran and ran and ran, they poured anti-freeze in in place of the oil, it still ran, the worst they could get was it would get so hot it would stall - then when it cooled down would start right up again. I would have liked to have seen that myself.
I'm in total agreement with Old Buzzard here, there's either a broken ring or piston ring land on that cylinder. Hard to tell how much of a ridge is in the cylinders. If it's a damaged piston/ring and you really want to run that engine, then it's time for a bore job. I'm going to sound like a broken record here, but find a 194 cylinder head, casting #3864883, it will bump up your compression to 10.5:1 with a .060 cut off the heads surface. It'll still be around 9.5:1 with just the head swap. Now, I have a flyer that came with my Langdon's Stovebolt Catalog, and they sell a reconditioned 194 head assembly for $125.00, to me, that's a bargain. Be sure to upgrade to an HEI distributor. To put a 250 into a 62-67 Nova/Chevy II you have to use a front sump pan. Only thing is, when you do that, you lose the ability to check your oil; no dipstick. You'll have to, drill the 250 block for a front sump style dipstick, or make an oil pan mounted dip stick. 250's are rear sump engines, and the 250 dipstick will go into the low point of a from sump pan. I did know a fella once who put a 250, with a rear sump pan, into a 63 Chevy II 2 dr sedan, and the rear sump pan did clear the cross shaft and steering linkage, but that is not supposed to work (?). Butch/56sedandelivery.
I totally agree with drgnwgn289 I would also suggest a bore gauge and dont swing the gauge fast or hard from side to side take a slow and accurate reading at top and bottom then mic it and not with calipers to get your readings as he stated....
Hey dude, whatever you decide to do.......its best if you freshen her up with at least new rings and gaskets....that way you'll know the shape before putting her in. While you have her down, take the engine down to the machine shop for a machine honing session.....relative cheap, plus they vat the block and clean it........cheap insurance. When they see that little mark, chances are they're gonna magnafux it.....so your mind will be at ease...........a good hone job, everything cleaned up, your good to go.........
this is good advice. but just to clarify, don't re-ring it without having the cyliders honed. the rings will take a long time to seat...if they ever seat at all. then it will most likely burn oil, smoke, foul plugs, get fuel in the oil and you'll be worse off than when you started. 56sedandelivery is exactly right about how hard it is to kill a 250...or any chevy or gmc 6 cyl. Have you ever seen one of those oil-attitive companies that give demonstrations at shows and swap meets by first using thier product, then draining all the oil, removing the oil pan and runing the motor for hours on end? They all use chevy 6's...
The late Chevy inline six family is as tough as nails. As is the Ford inline six family and the Chrysler inline but slanted six family. I've got a 250 with a CLifford finned 6=8 cover, Offenhauser 3X1 manifold, chrome side covers sitting in the garage waiting for a ride. You piqued my interest in it again so I need to do some thinking on where to put it.
My personal 2cents is If your already running the 194 for now,And that 250 looks like it could use a rebuild AN you want to use the perfromance parts you have along with other up grades.Why not just do the rebuild on the 250 and then put all your goodies on it after it,s nice and fresh.Why do the job twice when you can and will be much happier in the long run. Put a set of 307 piston in it along with the 194 head and you'll be looking at ruffly a 10-1 compression motor and a better cam. then you have something much more power & better performance in the long run.
Thank you all for the advice. I want to do what is right for the least amount of money. I need to do a clutch job on it and the current motor leaks a bit. So I was hoping that when I opened up the 250 I would find it in good condition that I could put it in and run it for a few years then pull and rebuild it when it really needed it. My plan is to use the 194 head I have as everyone has suggested. If I am going to go as far as a rering and hone job I am at the point of might as well rebuild it. The cost savings is not worth the uncertainty. Looks like I have some investigating to do on how much to rebuild and where in the hell in this economy I will find the money to rebuild both the motor, the head and the clutch.
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