RAMBOW

Just a couple quick questions.

Do rods need to be mounted to the crank with the spit holes inward or outward?

Other than that, is there any rhyme or reason to their direction on the crank? (other than the spit hole & the direction of the piston itself)

I recall hearing something about the beveled edge of the large hole needs to face outward- but for the life of me i can't tell, some look like one side is beveled more than the other, and some barely any bevel... Plus that doesn't make any sense since the bearing sits in there anyway and is square to the rod, not beveled...

Thanks-
Ben

Edit... A little clarification-

Reason i am asking is, when I initially bought my motor... I got a virgin bare block, and a matched set of Rods/Pistsons & crank that came out of another block that had cracked from non-winterizing.

All machining is done, and i'm finally starting assembly. Got the crank in yesterday, and i'm getting ready for the rods & pistons- I just want to make sure they get installed right.

Ozzie

The spit hole goes inward. The notch in the piston (and "F") goes forward. There are specs for bearing clearance and side clearance between the rods.

RAMBOW

Thanks!

Apparently my Chevy friends were confusing me. Stuff like this is the reason people say you can't build an olds motor like a chevy. Another friend found this for me:

http://www.realoldspower.com/phpBB2/...er=asc&start=0

Shows that olds rods don't have the camfur & flats on the rods(whcih explains why i couldn't see a clear difference), it is the offset of the bearing that clears the radius on the crank journal. The spit holes or the notches are what have to be right.

Think i got it now.

Ozzie

You're right about Olds being different than Chevy. They were both GM products, and basic techniques apply, but there is also a lot which is different.
Usually with a conventional rebuild, it's a good idea to have the pistons and rods operating in the same cylinder that they were in before disassembly. In your case this won't apply. I once did a rebuild on an old Rambler engine with parts from different engines. It worked out well, and it is still running today, but it's good to check for certain things. If there is ANY ridge at the top of the cylinder wall and you install new rings without removing the ridge, there is a good chance that the top ring will break. Also you probably should check the piston to cylinder wall clearance. In a new Olds engine it is close (0.0015 to 0.0020") at the skirt. Some rebuilders go bigger. You probably should check all running tolerances before assembly, especially if the donor engine had noticeable wear. This will avoid piston slapping and problems with the rod bearings. If there is minimal wear on the old parts, it's O.K. to use them. And be sure to use some assembly lube so it won't start dry. Also cleanliness helps so you don't get abrasives or other crud in your engine. Best wishes.

380 Racer

OK, here's a question. Know a guy who has a fat motor, was a 461 that he overhauled/assembled himself. Raced it for a few years and it ran pretty fast for what it was. When he took it to be freshened, the machinest found he had installed rod and piston assemblies backwards. He reassembled the same way and never had a problem since. These were TRWs and old wives tales claim add compression doing this with these. I would never have the gonads to try it tho.

captjim

Not "probably", definitely! Good advice. Also, install the #1 piston and then degree the cam, much easier to spin the engine and get accurrate readings.

captjim

Isn't there a chamfer (sp??) on the rods that goes outward?

cutlassefi

Not typically. Sometimes it's hard to tell one side from the other and you should make sure the bearing offset is correct and the squirt hole goes towards the cam.
But even at that, with the rod journal being undercut the bearing offset isn't as critical. And if you oil the pan instead of the cam that won't kill you either as I've seen some BBO rods with no squirt hole at all.

And when it comes to machinists being "Olds" knowledgeable, I'll say it again. A good one will know what to do know no matter what. My guy in Jax pointed out the squirt hole issue to me years ago, and he's not only a "Chevy" and "Ford" guy, but a real smart machinist period.

captjim

If I recall correctly, almost every engine has the rod bearing tangs facing out

cutlassefi

But if you install the 455 rod with the squirt hole facing the cam the tangs will be that way as well.
Also SBF install with the tangs to the inside not out.

J-(Chicago)

There's a thread on ROP where Jim L. & I were debating this issue. It depends on the year of the motor, as some of the crankshaft journals are cut differently over the years. Attention to detail is KEY in this situation. I do things my way, and he does things his way. I will see if I can find it. BRB.

J-(Chicago)

I can't find it. ROP is a vast place with a lot of **** to step in over there.

Stock rods before 73 had spit holes to lube the opposite cylinder and the cam, so face them that way, as not to oil the oil pan rail.
If you get rods with no spit holes, such as 73-up rods or aftermarket rods......you will need to put a bearing in the rod.

Usually the bearing will be offset to one side of the big end. Install the rod so the gap is to the outside...... to clear the crank fillet, and the bearing is offset toward the center of the rod journal.

Since most rods you encounter won't have a spit hole bearing.... it's better to look at it from the location of the bearing tangs.
The tangs go inboard, toward the camshaft, or opposite cylinder.

If the crank has an undercut radius on the rod journals.....like a CN crank for example... then it really doesn't matter which way they go BUT I feel it is bad practice to flip them just because you can. That's not a good reason to me personally.