New Rod Bolts

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Captainkirk

Captainkirk

Old School Mopar Warrior
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I am considering replacing my 40-something year old rod bolts with new ARP rod bolts on this build, although there is nothing physically wrong with them. My son is trying to convince me that even after pre-torquing and checking clearances that the big ends may require align-honing due to variances in bolt stretch from old to new bolts.
What do you think?
 
Captainkirk said:
I am considering replacing my 40-something year old rod bolts with new ARP rod bolts on this build, although there is nothing physically wrong with them. My son is trying to convince me that even after pre-torquing and checking clearances that the big ends may require align-honing due to variances in bolt stretch from old to new bolts.
What do you think?
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If the rods are 40+ years old too..I'd replace them also..
 
Is this something I can check with T-gauges and a mic after installing the new rod bolts?
 
The concern would be for the big ends to be distorted differently by the higher ARP torque: 50 ft-lbs AND thread lube versus 45 ft-lbs dry. (And perhaps by slightly different bolt diameters.) If you measure size and roundness, with the old bolts torqued vs. the new, you will need something that accurately measures and/or finds changes in the .0001-.0002" range, not just down to .001". I am decently skilled with a t-gage but I don't think I am that good. And you gotta check it all around, not just in one axis.

The ARP instructions caution that the ends should be resized after new bolts are installed. I am not smart enough to not try it however.... YMMV.

http://arpinstructions.com/instructions/144-6001.pdf
 
New rod bolts and re-size big end vs. new rods completely. I think the cost is around $50 more for the new rods by the time you factor in the cost of the bolts and machine shop labor.
 
Captainkirk said:
I am considering replacing my 40-something year old rod bolts with new ARP rod bolts on this build, although there is nothing physically wrong with them. My son is trying to convince me that even after pre-torquing and checking clearances that the big ends may require align-honing due to variances in bolt stretch from old to new bolts.
What do you think?
Click to expand...
He is right about the bolts being stretched to death, but the reasoning behind resizing the rods because of the new bolts being installed is that the new bolts have a tad larger shoulder and will expand the bolt holes and move material in the rod and cap towards the bores making them oval and can even misalign the caps.
As for the rods themselves...they are some of thee best factory production pieces in the history of the American v8 engine. I have rebuilt and used ,to the tune of 7400 rpm, the same set of 1970 340 rods, don't waste money replacing them...buy a good carburetor and or distributor 1st.
 
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Captainkirk said:
I am considering replacing my 40-something year old rod bolts with new ARP rod bolts on this build, although there is nothing physically wrong with them. My son is trying to convince me that even after pre-torquing and checking clearances that the big ends may require align-honing due to variances in bolt stretch from old to new bolts.
What do you think?[/QUOT

How many time have the nuts been cycled? Have they been cycled once, twice, 3 times.......how many.......I would be more concerned about number of clamp cycles than they fact they are 40 years old......if you know that they have been clamp cycled four or more times then I would make a case for changing them out....your car could be 40 years old or more...what pieces of it are you throwing away just because they are old?

Also when torquing up hardware, you are not torquing to yield and therefore putting a permanent stretch on the bolt.

My opinion
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When selecting the ARP bolts we've had better results using the "wave" style bolt 144-6401 instead of the 144-6001 regular "knurled" shank type. Some times the knurling when being installed will damage the rod. Also make sure the connecting rod is chamfered to accept the new ARP's tapered under head. If this is not done, it can sheer off the head of the bolt!
 
JBurch said:
How many time have the nuts been cycled? Have they been cycled once, twice, 3 times.......how many.......I would be more concerned about number of clamp cycles than they fact they are 40 years old......if you know that they have been clamp cycled four or more times then I would make a case for changing them out....your car could be 40 years old or more...what pieces of it are you throwing away just because they are old?

Also when torquing up hardware, you are not torquing to yield and therefore putting a permanent stretch on the bolt.

My opinion
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I honestly don't know...Once at the factory, at least once when the engine was built by Mr. Norm's, and once by me back when I built the engine back in '76-77. That's three for sure. Maybe more, if they were assembled and torqued during checks for sizing.
 
"I honestly don't know...Once at the factory, at least once when the engine was built by Mr. Norm's, and once by me back when I built the engine back in '76-77. That's three for sure. Maybe more, if they were assembled and torqued during checks for sizing."

At this point it seems as though you have a case for new rod bolts........Here's a question: when Mr. Norm built the engine, did they do a bolt up grade at that time? MP/Direct Connection had/has a heavy duty rod bolt package, they may have installed a set when they built the engine.
 
JBurch said:
"I honestly don't know...Once at the factory, at least once when the engine was built by Mr. Norm's, and once by me back when I built the engine back in '76-77. That's three for sure. Maybe more, if they were assembled and torqued during checks for sizing."

At this point it seems as though you have a case for new rod bolts........Here's a question: when Mr. Norm built the engine, did they do a bolt up grade at that time? MP/Direct Connection had/has a heavy duty rod bolt package, they may have installed a set when they built the engine.
Click to expand...

No idea...I was not the owner of the car at the time. Likely not, as it was only 3 years old when I bought it.
 
gliderider06 said:
New rod bolts and re-size big end vs. new rods completely. I think the cost is around $50 more for the new rods by the time you factor in the cost of the bolts and machine shop labor.
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True statement. However, if new rods require the rotating assembly to be re-balanced, the price of balancing could put it over the top. Just thinking out loud...
 
gliderider06 said:
New rod bolts and re-size big end vs. new rods completely. I think the cost is around $50 more for the new rods by the time you factor in the cost of the bolts and machine shop labor.
Click to expand...


Been awhile since I had a set of rods re-built, so I called my local shops (5 in all), 3 don't re-build any more, 1 got an answering machine, maybe they'll call back, last one gets $18.00 per rod labor to resize big end, add cost of bolts, Summit gets $72.01 for ARP set 144-6001 bolts for a total of $216.01 for them to be rebuilt.

That falls pretty close to Mancini's $269.95 for a set of Eagle SIR's; Eagle "H" Beams are $479.95 from Mancini. Scat "I" beams from Summit are $357.97.

Math isn't my strong suit, so with the exception of the SIR's (everybody hates them, think they are junk, they break with the engine sitting still, at least that is urban legend) every thing else falls out side the "around $50.00 more" range.

Maybe rebuilding the stockers isn't so bad.
 
JBurch said:
Been awhile since I had a set of rods re-built, so I called my local shops (5 in all), 3 don't re-build any more, 1 got an answering machine, maybe they'll call back, last one gets $18.00 per rod labor to resize big end, add cost of bolts, Summit gets $72.01 for ARP set 144-6001 bolts for a total of $216.01 for them to be rebuilt.

That falls pretty close to Mancini's $269.95 for a set of Eagle SIR's; Eagle "H" Beams are $479.95 from Mancini. Scat "I" beams from Summit are $357.97.

Math isn't my strong suit, so with the exception of the SIR's (everybody hates them, think they are junk, they break with the engine sitting still, at least that is urban legend) every thing else falls out side the "around $50.00 more" range.

Maybe rebuilding the stockers isn't so bad.
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I guess it may hinge on what my machinist will charge, then. Of course, I have yet to check eBay. I saved over $200.00 on the pistons and rings.
 
Math isn't my strong suit, so with the exception of the SIR's (everybody hates them, think they are junk, they break with the engine sitting still, at least that is urban legend) every thing else falls out side the "around $50.00 more" range.
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True to a point I'd never run them in a 500+ h.p. engine(again) but I've got a set in my 400 h.p. 360 with no issues after 5 seasons of racing..as far as using them the problem in my 416 was the ROD BOLT that failed NOT the rod!!!
 
stroked340 said:
True to a point I'd never run them in a 500+ h.p. engine(again) but I've got a set in my 400 h.p. 360 with no issues after 5 seasons of racing..as far as using them the problem in my 416 was the ROD BOLT that failed NOT the rod!!!
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Exactly my thoughts....
 
gliderider06 said:
New rod bolts and re-size big end vs. new rods completely. I think the cost is around $50 more for the new rods by the time you factor in the cost of the bolts and machine shop labor.
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My shop just quoted $144.00 to install and align hone, not including parts. So, around $225.00 roughly.

Versus....Eagle SIR I-Beam Connecting Rods

What would YOU do?
 
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3418645 con rod 749.9 grams. sir 6123cb con rod 593.1 grams. just weighed them. Stock means no change to ballance of your assembly, unless the piston and pin are not close to stock original weight.
 
It's a tough call..........my comments about the SIR"s are just that....comments.......not my opinion......in fact I do have a set in my 360, bought them before controversy sprang up here on the internet, so that puts them at like 14 years old or there a bouts. I bought them because they are light and I was looking to put together a light rotating/reciprocating assembly and they were/are cost effective.

Buy them........the shop that I got an answering machine called back.....they ger $25.00 a rod labor
 
Max1196 said:
3418645 con rod 749.9 grams. sir 6123cb con rod 593.1 grams. just weighed them. Stock means no change to ballance of your assembly, unless the piston and pin are not close to stock original weight.
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New pistons are weighing in at around 728 grams, which is very close the original piston weight of 719g but a ways away from the forged TRW's that were in there prior at 660g.
The Eagle SRI rods in my post above are spec'd at 605g....
 
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