I picked this 327 up for my 55 it had been sitting for years. The heads and cam were sold years ago. And it and been sitting for a long time without the heads and front cover. The cylinders were well oiled but years of garage dirt was everywhere. The pictures are after some serious cleaning. Looks like a fresh rebuild befor sitting in the corner for years. Does anyone know why 1,3,5,7 have large rod caps weights and 2,4,6,8 have small weights. Thanks Ron
maybe the 2468 rods were heavier and needed more weight removed to balance the set? or maybe it's not a balanced set?
I don't think it matters for a daily driver engine ,If you don't feel comfortable get the rotating ***embly balanced .I'll go check my 350 Its on the stand ,Because I've never noticed this .It might be factory...My 350 is the same way Weights are larger on one connecting rod compared to the adjacent cylinder .
I would take it to the machine shop and have them re-balance the rotating ***embly, or at the least have them check it out and make sure its good to go. I have had quite a few engines balanced and never was there that big of a visable difference between the rod balance pads, but I am no expert and have not seen it all.
Nice Forged Crank... Ditto on the balancing the rotating ***embly; the engine should last forever and spin up nice n' tight as well.
??? I pulled apart an all original 63' split window corvette Fuel injected 327 at the machine shop I worked at and all the connecting rods were the same on that particular engine and all the other sbc Ive pulled apart Ive never seen mis matched rods before. I also did a google search and didnt see anything. Id talk to a local machine shop about why its that way and about balancing the rotating ***embly before going any further.
Look at the cap in the pics. One is slitely thinner in the lower area,,the other is thicker. These rods were m*** produced from the factory,,and there are variances from set to set. I had an old racer friend that used to go through many sets to find 8 that he liked,,he wanted 8 with as small a balance pad as possible. His reasoning was that since all should be close to balanced the same from GM,,,,,if they have a small balance pad,,then the extra metal must be in the beam,,where it is needed. He never had rod failures with stock rods. Your parts look very good,,,,I like the pop up pistons. Block and steel crank look great as well. Good luck. Tommy
350 horse 327. Good engine, but if you've got to get heads you might consider getting the large chamber heads to kill off a little compression. They're 11 to 1 from the factory. And if I were even a little worried about the rods, I'd have them checked and the rotating ***embly balanced. It would definately be worth it in a high performance engine. Larry T
On second thought Why take a chance ,Balance the rotating ***embly and then you will be able to sleep tonight ........
After dis***embling at least a couple of hundred of those engines I can tell you its very unusual to have the balance pads like that in the same engine. In fact I've NEVER seen it. It's almost as though someone took 1/2 of the rods out of one engine and the other 1/2 out of another. Just to protect your investment if you intend to run this engine to its potential (It should be good for at least 6500 RPM) I would at least have the balance checked. Frank
Im just wondering ,If they are brand new connecting rods that have been balanced for the oversized pistons .I think that is the case ,I'd still get them checked or try to get more info on motor ......
Thanks everyone lot of good info. Ive had several 283. a 302 lots of 350 and never seen this set up on the rods. But never had a 327 and it appears to be a fairly well built motor thought someone might have seen a rod combo like this. If you flip the rods over thay look the same. Some good points are the factory rod weight and how thay are on the same crank journals 1-2, 3-4, 5-6, 7-8,. I have a set or 882 heads with large combustion chambers and using an trx1 tunnel ram but would like something that looks more period. Any ideas Thanks again Ron
Is it a small-journal crank? Post a pic of the entire bearing area of both rods... I'm wondering if you have half a set of the good, hi-po rods, and half a set of the earlier rods with less material in them. The tell is a little more material on the top part of the bearing area. There's a little out-kick, while the earlier rods are simply round in this area. -Brad
These pistons actually are 10.35:1 CR with 64 cc heads; everyone refers to them as 11:1 for some reason. 76 CC heads will knock it down to lousy quality gasoline level; probably something like 9:1. The posting above is also right, the smaller the rod end balance pad, the more metal where it does more good, BUT, it's actually in the ROD END, and that makes the rod end stronger. I would'nt worry about the balance pads. I have two of these 327's, one a small journal, the other large. Butch/56sedandelivery.
In my opinion, using 76 cc chamber heads to lower compression on an engine with domed pistons is going in the wrong direction.A set of 64-67 cc heads with flat top pistons is better for power and avoiding detonation.Of course I'm spending your money on new pistons
I've seen this lots of times although never noticed one with all the even numbered rods ballanced one way & the odd numbered rods ballanced different. Coincidence ? Don't know but there are also ballancing pads on the top of the small end as well. You won't be able to see them very well with the pistons installed though. Rods are ballanced on both ends not just an overall weight. Since the pistons are .030 over and obviously not original from the factory it would be a good idea to have the rotating ***embly reballanced. Looks like a great start to a nice smallblock. Piston numbers look to be a TRW forged piston.
Do you have a good scale? Weigh them and see if they come out the same. I'm betting they do. Out of 2 different engines, but made 2 different ways. Even if they do come out the same, I'd cross them up when I put it together. 1&2, one of each, 3&4 one of each, etc ,etc..
I would also weigh each ***embly just for the heck of it on a good accurate gram scale. Do the smaller pads appear to have been machined? Bob
Look for part numbers on all the rods to see if they match, and look at the very bottom to see if there is any raised letters on the bottom cap. That's quite a bit of difference in the balancing pads fo sure. Need some really upclose pictures to really tell. One other ideal, but rare is to look up towards the upper beam and see if there is a dimple on the rods about a inch below the pin. I've only seen one set of sbc dimple rods, but have seen several bbc dimple rods.
I've never seen a part number or a casting number on any Chevy smallblock rod. Casting marks such as an X or an O on the cap is generally a large journal thing as well.
I just took a big block of mine apart and it has two different sets of rods in it. It appears to have been balanced and the balance pads on the caps have different amounts of material on them. Look to see if the balance pads have been ground on. Another thing that gave mine away was the duplicate numbers on the rods. Must have spun a couple of rods in the past and had them replaced. I ran the block suffice code and it comes back 66 Corvette 350hp 327. Some Corvette restorer would really like to have that block.
The rods with the heavy balance pad don't have as much meat in the rest of the rod....are they weaker? (stirring the pot....)
No, but I complained to chevrolet because they caused my 350 in my p.u. to run on after I shut it off because of the heavier rods on one side. Lippy
I have never built a set of rods with that much of a pad difference. I used to go thru 55 gallon drums of rods to blueprint and if they weren't wired together as a set I would go by there looks, and get the pads as close as possible. When you go thru hundreds of them you will see alot of differences. If I did anything to them rods, I'd have them weighted first, new rod bolts second, and then have the big end resized. Blancing an engine was a natural where I worked. All depends on what your going to do with it.
The pics tell the story... The rod castings are not the same. The big end balance pads are fatter on the thin rods to make up the weight difference. FAT end = thin pad , Skinny end = fat pad.. Factory motor, 8 rods from the parts bin, factory balance.. If they weigh the same, run them. If you are going to spin this thing 7500 all day under a full load...Replace them. BTW x2 on the nice steel crank ! Dave
One of the basic rules of engine building: If you have doubts about a component, do not use it! A whole set of rods are reasonable enough to get and send them out with the balance job. You'll sleep better. Bob
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