So I have an SBC lying around which had a cracked head(s) causing it to steam heavily out the exhaust after startup. I ended up junking the heads. I figured I'd go ahead and refresh the bottom with new bearings and rings. A local machine shop checked the block and crank. No boring or turning required and ok'ed using standard bearings and rings. So I picked up a basic rebuild kit and NOW I notice the #6 connecting rod is bent. Like BENT BENT... argh. This engine I want for a driver. No high rpm and around 250hp. I'm thinking the leaking head hydo locked the piston at some point and did the damage? The crack was in that area. Can I scavenge a rod from a similar engine and keep going? Or.. replace them all? Remember, this is a grocery getter, not a powerhouse.
Try and find a rod that weighs the same . New cast or hyperutectic pistons are pretty cheap especially if its 350. It would be a good time to recondition the rods replace the bolts for a bit more. It's apart now is the time.
Hydrauliced on a start up, at one time I had a 65 Chevelle that I bought with 13,000 and took it apart a 117,000 that looked the same. The compression check was always 15 psi low and a very slight miss at idle.
It's easy to spend someone elses money doing something that isn't needed isn't it? It will be fine for what he wants to use it for with a replacement rod and maybe a piston if it shows damage to it.
Yep, I have a rod hanging on the wall that is shaped similar after dropping a valve in a SBC about 30 years ago. I just replaced that rod and piston, sleeved the block, and ran it for a long time after.
I worked for a Lincoln/Mercury dealer where we had 2 - 3 Pantera's in stock. One was a bit sluggish. After a customer test drive it developed an engine noise. Since it was brand new, it got a new short block. We found there were two bent rods. The air intake on a Pantera is behind the rear window and there is a grille above the air cleaner. In the winter snow would cover the grille and as it melted it would run down into the air cleaner. Eventually it would fill a cylinder with water. This would mainly happen in holding lots and some Pantera's set in lots for a couple of years. Try to start the engine and you could bend a rod or two.
I would be taking a real close look at the other rods and pistons, especially on the bank with the bad head gasket. If #6 took a hit hard enough to bend the rod, there could be damage in those other rods or pistons that isn't obvious. I'd look at all the pin bosses for cracks if you reuse any pistons, mic all the rods, check for straightness and polish out any stress risers. I always have rods resized if new bearings are going in. Cheap insurance against putting a window in the block. I don't think new bolts are necessary for your application. You don't have to spend a bundle on this, just make sure that one of those rods doesn't turn into a buzz saw that tries to cut the block in half. I hate it when that happens.
With my last SBC build, it was close to a tie of costs between having the old rods reconditioned and getting a new set of **** rods. Their entry level rod is pretty good IMO. Well... now they are over $300 a set for starters. I paid just over $200 for mine 8 years ago.You may be fine with a single new rod. Or a used one. But have them all checked out. The price I was quoted in 2015 for having my stock rods checked, resized and fitted with ARP hardware was $175.
that looks like a powderedmetal rod compe***ion products catalog had a run down on them when they first showed up they explained they are so precise that out of the forge they are n tolerance therefore no balance pads the shop that balance mine explained to me it was difficult to find anywhere to remove weight they were a bit more precise than gm
If you have an engine rebuilding co. nearby, go ask them if they might have a decent rod and same piston you can buy. Likely you wont be able to buy one new and be sure it's the same as that one. Once you have a donor rod and piston I'd weigh an existing ***embly, and make sure the new donor is close to the same weight.
In order to bend that rod, the other components in the engine also received some abnormal stress levels. Do the rod bolts need replacement ? Have the rod bolts been torqued more than once ? I'd just bite the bullet and buy a cheap set of replacement rods with better quality rod bolts and swap them out rather than wonder if something might fail later after its all ***embled and installed. I have to wonder how a used engine didn't need any block work if it hadn't been rebuilt sometime or another.
Just got back from the local machine shop where I’ve been doing business for 39 years. Old school shop which are hard to find these days. Stan hooked me up with a replacement rod and pressed my piston on. Good to go.
Yep-bent #1 rod in my 57Fuel Injected Chevy with gas leaking by in FI unit. Replaced rod and piston-no problem.
SBC are a very tough little engine. Rod -piston donor, you will be fine. It's bin done countless times. I did this very thing when I was in high school, and continued to beat the **** out of that SBC for years.
The rod's you have look to be of the newer, powdered metal variety, with fractured cap's. Hopefully your machine shop checked the weight of the replacement rod to make sure it was a close match. IIRC, the powdered metal rod's are lighter than the standard old style rod's.
I bought a 71 Ford pickup from a neighbor who was rebuilding it from a wreck. He told me it had set out with the hood off and gotten water in the engine so he ended up replacing the heads. It was a 360 and it ran fine and was low mileage. I needed a tow truck for my race car. On a early morning trip to do a moving favor, my brother-in-law was driving and it developed a dead miss. I was napping and he said it made a big bang and started missing. I told him to pull over and I would check it out (expected a plug wire off). Nothing appeared to be wrong, but it did have a dead miss. While checking things I pulled the dipstick and found the end of it missing. We started and stopped the engine multiple times and finally decided we needed a tow. No cell phones (1975) so my brother-in-law got a ride to find a phone. After a long day, we finally got back home behind a tow truck. I started it up to drive it in the garage and it made another bang and quit. A rod had broken in the middle which was the cause of the miss. The piston and half the rod was up in the cylinder while the other half was still on the crank. The last time I went to start it, the piece on the crank went up and broke the cam. When I tore it down, it became apparent that the rod had been bent probably from water in the cylinders. The truck ended up with a 390.
What's it cost to do it twice ? I suggested stuff that's pretty cheap to do now while its apart. A used rod is about free. Free to weigh it. Having all 8 checked is not that expensive or mic them yourself . Haven't had stock rods reconditioned in a long time but it's not horrible. You don't have to go ARP bolts. I broke a rod bolt on a cheap overhaul ( rering ) once was not pretty in a 61 chevy Impala . Back then $50 would have prevented that . That said thousands of SBC redone with original bolts no argument . New pistons can be had for about $100 . Not saying there going to fit his block better or worse . Its what id do unless I had a identical used piston. I cant really see how bad his is . I don't know his budget or how long he plans on driving it . Im aware money doesn't grow on trees . I once emery clothed a rod journal smooth and installed a used bearing from junk engine . we sanded down the rod cap on a gl*** plate a thousands and ran it for about a year in a 55 chevy PU that had a 235 in it . Years back I used to use the $169 northern auto rebuild kits with pistons to do a cheap overhaul or rebuild and steal valves from used heads to get what I could grind to fit on my old Black and Decker grinder . OP I'm sure what you're doing will run fine as long as the piston is OK . I would at least measure the skirt to see if not collapsed . Sure you did
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