Rod and Cap mismatch?

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dibbons

dibbons

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This 340 I purchased is weird ('73 block, front sump oil pan, forged crank, '68-'69 unsilenced air cleaner, '68 factory intake manifold, '71 440 (low-performance) Carter AVS carb, 292/.509 purple shaft cam, .040 over cast aluminum pistons with four notches).

The rods and caps were kept together the way I found them during disassembly. However, they kind of look like they are all mixed up. foto #1: The one bronze-colored rod has steel colored bolt heads and a steel colored rod has bronze-colored bolt heads. foto #2: The rod cap with the number "6" looks like it has nothing to do with the rod it is mated with. foto #3: Rod numbered "4" has a large ledge/edge on the left were the parting line is (maybe that is normal?). foto #4: Rod numbered "8" just looks like the cap and rod don't match at all (at least to me).

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take them to see good machine shop and have them checked for size, taper, out of round, etc. on a rod(and pin honing)machine, Sunnen is a good one. It'll cost some money, but this is probably the most stressed part in the short block. I wouldn't take a lot of chances, here. That being said, other than the stamping on no 6, nothing is that obviously unusual, to me anyway.
 
I have found that some rods have been reconed with mismatched caps but are fine after machine work on inside but don't look good on outside, they still work good if they are done correctly.

I would still have them checked
 
The #6 rod pictured has the bearing in place and tangs on same side, oil hole (in bearing) matches on the other side. The bearing has a deep scratch/groove showing a copper color.

The rods are not numbered 1 thru 8. They appear to be marked as follows:
one rod marked #1
two rods marked #3
one rod marked #4
one rod (cap) marked #6
three rods marked #8

no rods are marked with #2, #5, #7

A real "Hodgepodge"!
 
dibbons said:
The #6 rod pictured has the bearing in place and tangs on same side, oil hole (in bearing) matches on the other side. The bearing has a deep scratch/groove showing a copper color.

The rods are not numbered 1 thru 8. They appear to be marked as follows:
one rod marked #1
two rods marked #3
one rod marked #4
one rod (cap) marked #6
three rods marked #8

no rods are marked with #2, #5, #7

A real "Hodgepodge"!
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I think you have a "veteran" engine, one that's been rebuilt a couple times. It may not be a Virgin anymore, but if the pieces are right, it can still work just fine.
 
You can have the rods machined with new rod bolts or for about the same price you can buy a new set of rods. Something you don't want to trust.
 
Some of my rods weren't numbered either. But my caps were all attached to rods. I left the caps n rods together, put the numbered rods and caps where they should go, and plastigaged them with new bearings. All within spec. Make sure you orient the cap properly with the rod. When rod is installed the pad with the number faces the outside of the block. That means oiling grooves in cap face/spray oil to inside of other rod
Hope that makes sense?
I'm doing exact same thing right now so I can take pics if you want? Or check out my"273 302 318 340 build" thread.
 
I have a set of ARP bolts, now it's going to be up to the machine shop to get things sorted out/reconditioned. I think the date on the rod bearings was circa 1985. I noticed all the oil holes in the rods were facing away from the cylinder walls before I disassembled everything.

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toolmanmike said:
You can have the rods machined with new rod bolts or for about the same price you can buy a new set of rods. Something you don't want to trust.
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Which one don't you want to trust? The new china rod or the good old mopar rod?
 
brian6pac said:
Which one don't you want to trust? The new china rod or the good old mopar rod?
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In the case of the op, neither. I wouldn't buy a crank without checking it either. When I built my 273 I installed new rod bolts and reconditioned the rods but they were all marked and not a mis-matched mess like the op's are. His might be ok but it makes you wonder.
 
Often when I'm done making up a matched set of rods there will be no symbols or #'s left at all. To me it's more important to have the weights correct as a set, and to choose the best of multiple cores to offer the best of the pickings. Wrist pin hole on center, big end weight, small end weight and general appearance. Copper coted stuff is not a concern. I remove the #'s so there is no silly questions as to why there's 3 #8's (for example).
 
dibbons said:
I have a set of ARP bolts, now it's going to be up to the machine shop to get things sorted out/reconditioned. I think the date on the rod bearings was circa 1985. I noticed all the oil holes in the rods were facing away from the cylinder walls before I disassembled everything.

View attachment 1715122604
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on v8s oil spit holes on big ends are supposed to face camshaft.
 
I think I also found the notches in the pistons pointing to the rear (maybe the previous owner wanted it to run backwards?).
Edit
Wrong statement above. I double checked the piston arrangement on the connecting rods. The foto below shows cylinder number 8, so the piston notch is correct, it is pointing forward (but the rod is still turned around so the chamfer is facing away from the crankshaft journal).

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looks like it was tossed together to get it out the door. ARP bolts require you to resize the rods anyway as they put a different stress on the caps. These old rods wee not cracked, ie. not a pair until they put a rod on a cap and them finish honed the inside, now they are mated. I dont know why 4 brow pistons are clocked anyway., the reliefs look the same size.

brain fart, its the pin offset....duh.
 
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I recall back in the day (when building big blocks) I had a Mopar expert tell me to point the notches on the pistons 180 degrees off for added mid-range torque. His claim was the offset of the piston pin (when orientated the other direction) gave the added benefit. I tried it & I have to admit that the 440 I built really ran. I did not document it with a back to back build off but it worked that way for sure.
 
In post #10, it looks like some one took "reversing the parts" one step too far ! That rod 2'nd from the rear is in backwards. Chafer and crank radius would have been a close call.
 
MichaelB. said:
I recall back in the day (when building big blocks) I had a Mopar expert tell me to point the notches on the pistons 180 degrees off for added mid-range torque. His claim was the offset of the piston pin (when orientated the other direction) gave the added benefit. I tried it & I have to admit that the 440 I built really ran. I did not document it with a back to back build off but it worked that way for sure.
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Reversing an offset/production piston
 
If this is ever to be done, Piston ONLY gets reversed, if it can be, must have an offset wrist pin bore and a piston crown that is uni directional. It does seem to be of an advantage for applications that low piston speed is usually not a factor , as in "hobby stock" circle track class. The sound is detectable though.
 
years ago, a guy, I know, (Not Me!)was assembling a 426 hemi, and didnt pay attention to the valve reliefs and/or piston notches, and bent some stuff when he first rolled it over.
 
When reversing pistons, the common thing to do is put #1 plston/rod backwards in #2 hole, #2 piston/rod in backwards #1. Thus maintaining the proper chamfer/squirt-hole, valve relief relationship.. common stuff back then.
 
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