Do you think the engine was run with way to much spark advance? Knock knock.... If one piston has that kind of damage I'd suspect the others may too. Although it doesn't mater since you'll be putting in new pistons in anyway.
All the other pistons are fine, I don't know about the spark knock, but it def could be and he just didn't understand that's the noise it was making. I think that's unlikely as he's a "car guy"......but it could be. The pattern is what's bothering me - seems like it would be worn all across or the bearings would be pounded flat.....
One of the mysteries of this engine is what happened to the screen over the end of the oil pick up tube? You can see in these pics the imprint of the screen and where it might have been soldered on. I don't know if the screen got chewed up in the gears and run thru the engine or if maybe the tube didn't have one when it was assembled? Either way - it's a puzzle. Of course my assumption is it was there, came off and got chewed into tiny bits and sent thru the works......either way we'll put a new one in. I've looked thru the sump and can't find any trace of it, and absent a brass magnet or a complete stripdown of the gearbox I don't know if I will. So. My plan is to set the gearbox on it's end and spray some clean clear solvent in the case and see if anything washes out - it not I'll call it good. I already stood it on it's end in a clean pan to drain every smidgen of oil out and found no pieces in the oil....I'm thinking it's either been digested or it's in the oil filter in a billion bits.
Heard back from the machine shop, the bores are good, we can simply give it a good hone and keep the same size pistons. We're going to put all new pistons in it as one of the pistons broke and we don't want to take a chance on the others - but we're having a hard time finding some. Everyone is out of stock right now. The crank is straight and not bent or worn, so we'll just give it a good micro polish and call it good. The rods are also straight and OK. So, I'll drop off the new pistons (if we can source some) so they can balance the assembly then it all goes back together. With any luck, it'll be home for Xmas!
Thanks for the consensus. I thought that might be the case. The broken piston made me think knock. I have seen that before, but those bearings had me puzzled. Guess your customer needs to run good gas & less advance on the timing.
I don't think the gas was the problem, I think he just mis-timed it and didn't realize the sound he was hearing was not a rattle but detonation. I'll get it running in the test bed and get the initial timing set, but the best way would be to put it on a dyno and set it there. He's running an electronic distributor that has a bunch of built in advance curves, we'll pick one that's not quite so aggressive.
Pistons came in today, so I ran them over to the machine shop. The head and crank are already done so I brought them home with me. The block still needs to be honed to size, but we wanted to have the pistons before we did that - and he'll also swap the pistons onto the rods for me - while the old pistons are off he'll double check the rods to make sure they're straight and the big ends are round. He'll also match the weight of the new pistons to the old ones if they're close enough, otherwise I'll take the rotating assembly over and they'll balance the whole thing together....but they think just matching the pistons up will do it. The block and pistons should be done by midweek......and I'll go pick it all up and get ready to build it up once the rest of the parts we've ordered come in.
What's the old Chinese curse? "May you live in interesting times"? My machinist friend called me this morning to let me know he'll have the block done today, and that he was going back home cause he's had Covid for the last week and it's kicking his butt! Yet he's still going to work every day because he can't afford not to and the shop can't do without him as they're so backed up with work. I think the only reason our stuff got done so quickly is that it was fairly easy and he slid me in ahead of other work. So, I'm going over tomorrow to pick it all up....I'll have plenty of hand sanitizer, latex gloves and mask on and just hope for the best. I dunno if I need to spray everything down with Lysol when I get it home or what? I sure can't afford to get it, what with my other health issues and upcoming surgery in early January! My daughter called and said both her oldest boy and she had it and the whole family is quarantined - fortunately they live on a small farm so they have room to get out of each other's hair so they all don't go nuts being cooped up together. As for the block, he said it cleaned up with very little effort, he had to straighten and resize one of the rods slightly, and everything was close enough in spec that it took very little to balance it again. So, once it's all home I can start the cleanup and measuring..... New parts should be here both today and tomorrow, then I can get started in earnest. With any luck it will be home in time for Willie B to have it in the car by Xmas! My health issues are kicking my butt too, and really limiting what time I can spend in the shop - some days I can't even get off the couch! I have yet another Dr. appt Monday, we'll see if he can get me over this crap.....I'm still convinced it's a meds issue. Edit: My buddy is going to loan me his surface plate and burette so I can CC the head, and calculate the compression ratio...I'm sure it's fine but I want to document everything.
So I went over to the plague infested shop today and picked up the block and pistons, I think I got out unscathed, they carried the stuff out and put it in the car for me, and they were wearing masks and latex gloves. I got it all in the shop but the block will need a lot of cleanup before it's ready to build....I wonder if safety solvent kills the 'Rona? The box with the belt drive came in and it's a really nice bit of kit - he got a great deal on it IMHO. The cover and back plate are a lot heavier than I expected, but the whole setup is nicely made with great little touches like the TCD mark on the cover. Other projects will have to take precedence over the next few days, but I plan to get started on the build up phase early next week with the goal of shipping it by the end of the month or very early Dec.
Nice looking bit of machine work, glad they are taking it serious at that shop, masks and gloves. Stay safe, get the meds checked, you do not want the covid at our ages. Project is looking good, but you have a lot of other things to mess with too. What surgery is planned for January? Forget what you might have written earlier. Good grief getting old is a bitch. Take care, mask up. Don
Hey Dave maybe we should form a club. I've only been bone on bone in my left knee for 6 years or so. My right one is close. I've been getting a Monovisc shot in my knee every 6 months to lube the joint. Helps for a while. Let me know how it goes when you get that new heim joint.
First up today, I installed the cam bearings using my special came bearing installerator....a piece of all thread with some specially sized bushings and washers.... Then, this afternoon I worked on the cylinder head and rockers..... First up was to clean it, then set the valves in, install the stem seals, then the new double springs, caps and keepers. I don't know why the gasket sets only come with 4 stem seals as I and every other engine builder I know puts them on all the valves. I keep extras on hand so I'll always have a full set available. Next I run a tap in every threaded hole to make sure there's no crud in there that will keep the studs from setting properly. Lastly I'll run my flat block over the head surface with some 1200 wet or dry to make sure the head surface has a good "tooth", then I'll give it one last clean up. I also assembled the rocker arm assembly with a new heavy duty shaft and new forged Cooper S rockers. There's nothing wrong with the sintered rockers on here as they tend to wear the shaft more than the rockers, but I've read that they're not exactly real accurate for geometry or ratio - these Cooper S rockers are an honest 1.13% and well made, so I prefer to use them with the cam we're using. The shaft wear doesn't photograph well, but there was definitely some wear on it - they're considered a consumable and I always change them. So that should do it for the cylinder head, valves done, new stem seals, new double springs, new rockers and rocker shaft. Next up some more work on the block.