Conn Rod Work - Excessive?

[cwestra]

My machine shop guy told me today that he recommends I replace the rod bolts before I re-assemble the motor.  That's great.  I was going to do that anyway.  However, he is telling me that he is going to have to re-hone the bore on the rods because of this, at a price of $120.  He claims that the new bolts will tend to distort the rod end differently, requiring them to be true'd up.  Is this correct?  How critical it is?

Also, I have full floating rods and on the small end he recommends new bushings be installed.  Is this an automatic on any rebuild job or rarely done?

Total, this will end up costing me an additional $225 not including the rod bolts.

Any advice would be appreciated.

[quagmire]

He's right.  New rod bolts should be mandatory on any performance or even stock build.  Especially when they are 40 yrs. old!  Pressing the rod bolts in and out will likely distort the bore, and the bushings in the wrist pin bore do wear out.  Seeing as rods and there fasteners are the most stressed components of the engine, I would not skimp out there.  The last thing you want after a fresh build is a thrown rod or wrist pin knock.  You may be able to find a new set of rods for that price.  The Eagle SIR rods have ARP waveloc bolts and are stronger than stock.  They aren't much more expensive, but even new rods may need honing. 

[bb71challenger]

I know it might sound like an unnecessary step but with all the expense of a rebuild I would bite the bullet and have the rods resized with new bolts installed. You want to have peace of mind that the rods are not the weak link and can take the punishment.

[72cudamaan]

absolutely what they said.  I was a automotive machinist for 23 years and u cant go wrong by doin it right

[Katfish]

Just curious, what is the cost of the work needed vs buying new rods?

[Katfish]

Looks like it's a wash, Mancini has a new set for $240

http://chucker54.stores.yahoo.net/corodse.html

[bb71challenger]

Something to keep in mind is the claim of "50% more strength than chevy pink rods".  I know that the larger 318 rods are meatier than 454 "pink" rods. I am sure the new rods are more than good enough and I would probably get them just because they are new metal and have not had all the fatigue of the old ones.

[femtnmax]

I ended up buying new rods.  They came with new small end bushings, ARP bolts, there are collars that positively locate the rod cap on the rod, and they are weight matched as a set.
Having the machine shop do the work probably won't include the locating collars or the weight matching.

[71chally416]

I agree with the new bolts and resizing the big end should be the minimum done on any performance rebuild re-using the stock rods but I've never seen a pin bushing go bad on a SB mope rod. I have seen the stock bolts stretch out and the nut back off though. I found one laying in the oil pan on a stock 383 that kicked a rod.

I also agree you can buy new rods for little more than what you'll spend reconditioning the old ones, so it's your call. I also got new rods for my 416 because I didn't like the looks of the stockers and couldn't see putting money in them. The 340 rods I used in my old 318 were way more consistent forgings than the ones I had for the 416 for whatever reason, so I elected to just resize and use them. If you have a pic of yours  I'll give you my opinion.   
 

[cwestra]

I agree with the new bolts and resizing the big end should be the minimum done on any performance rebuild re-using the stock rods but I've never seen a pin bushing go bad on a SB mope rod. I have seen the stock bolts stretch out and the nut back off though. I found one laying in the oil pan on a stock 383 that kicked a rod.

I also agree you can buy new rods for little more than what you'll spend reconditioning the old ones, so it's your call. I also got new rods for my 416 because I didn't like the looks of the stockers and couldn't see putting money in them. The 340 rods I used in my old 318 were way more consistent forgings than the ones I had for the 416 for whatever reason, so I elected to just resize and use them. If you have a pic of yours  I'll give you my opinion.   
 

Unfortunately, I don't have a pic to send you of the rods, however, they are stock pieces.  I plan to check out replacement rods so if you have any recommendations that would be great. 

With new rods should I worry about balancing the rotating assembly again?  Block was bored .030" with new KB pistons.

You mention that your 340 rods were much more consistent forgings.  How did you determine that?

Is the distortion on the big end caused, then, by the removal process of the old bolts, or is it from new stresses from new bolts?

[71chally416]

The real reason to resize the big end is to get it to the right size to get the proper "crush" on the bearings. The cap will also be slightly mis-aligned after changing the bolts.

What I look for with stock rods is beef on the crank end and a good amount of metal (the area where your feeler gage touches the rods when you check the side play) and if all the balancing pads are close to being equal. I've seen some that look as though the big end hole was machined off-center of the forging. Ditto with the small end. All the machined holes should be centered on the forgings.

[moper]

Depending on the rod and the effort of the shop, your new rods may need the same big end hone. It's normal. And weight matched means they all weigh the same as a unit. But they dont get factored as a single unit in balancing, so that's a load of crap. Not that you dont need to balance the assembly...

[cwestra]

Depending on the rod and the effort of the shop, your new rods may need the same big end hone. It's normal. And weight matched means they all weigh the same as a unit. But they dont get factored as a single unit in balancing, so that's a load of crap. Not that you dont need to balance the assembly...

It seems odd, to me, that new rods would still require honing.  I would think that would be done during manufacturing.  I can see doing it if I was running passes at the strip, but would I really need to do this for a street machine?

[71chally416]

An inside mic will quickly tell you if they do or not. The small side of the tolerance is ideal.

[moper]

That all depends on two things. The guy doing the final torquing, and the guy who tells him how to do it. If you are say, 440Source, his guy uses the wrong lube and the wrong spec. So when the builder torques it properly, the cap distorts and you're back to needing it honed. Where it gets used matters little. It is either right and in spec, or it's not. Take an aftermarket rod from any low to mid price range and cycle it, then torque it properly and have it checked on a rod bore gage, and you'll see what I mean.