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Discussion Starter #1
Hey guys,

if im using stock rods that are in VERY good shape and still very concentric, do I have to have the big end honed when stepping up to ARP rod bolts? Im just wondering if I can just use the new bolts as getting them honed is a ripoff around here, and for the price I could just buy brand new rods, which id rather not do. This is going into a very mild stock bottom end smallblock. Everyone says that the stock bolts are a huge weak link, so i figured new bolts are better than nothing right?

whatcha guys think?
 

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Unless you have a dial bore guage and can measure them, I would resize them. More than likely the bores will distort, mostly due to the better clamping force of the ARP fasteners, and you'll have to resize anyway.
 

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Discussion Starter #3
I do have a dial bore gauge, my dad brought it home from his job. What is an acceptable out of round spec on the big end?
 

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While I'm not against dial bore gauges, I will say they can be "inconsistent", especially inexpensive ones. It's a good idea to be able to confirm what the dial bore gauge is telling you.
Having said that, yes, you should check the rod bores. Your machine shop should be able to check them in a matter of minutes as a courtesy (if they want your business). They should be round within a few tenths, but the 12:00/6:00 measurement is what you need to focus on. If you can measure your rods before, and after you change bolts, that'll tell you how much they change. If they change more than a couple tenths, I'd have them re sized. If you're torquing your fasteners, don't forget to cycle them a few times (like 5 times) before you measure anything. After you torque and loosen them a few times they'll take a set and the threads and under the head of the bolt, or the nut, will all "mate" changing the amount of friction it takes to tighten them, and how far they'll stretch with the same amount of torque.
 

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the most exact mannor to measure the rod big end is with the gage that is mounted on the sunnen hone machine.

it is common to find that even with stock bolts, the roundness will change with as little as 5 pounds of clamping force...
and distortion will be off the map with a replacement bolt........especially if it is a press in bolt with a nut.

average cost to resize a rod..cut the cap and then press in bolts and then deburr and hone it round....

ten to fifteen dollars each........plus the bolt kits

I dunno about canada,...
but,
if you feel that that relative cost is too much at your local shop,..then ship it out to another shop.
 

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the sunnen gage that is mounted to the rod hone machine can do something that no "hand held" dial bore gage can do.....
and that is being able to tell if the bore is square to the sides (thrust-endplay) sides of the rod....
 

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Take them to the machine shop and have them checked, it will cost you a hell of alot more if you run them and then have to pay to have repair work done to the bottom end , and on a side note i even have new rods checked espically the cheaper ones as you might be supprised just how far off some of the cheaper rods are when you get them new
 

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Discussion Starter #8
So general consensus then is if installing new bolts I have to resize?

What if I measure before hand, install new rod bolts, then measure again, and if out of spec get them resized. Is that a safe route to take?
 

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so its probably actually safer to keep the rods the way they are now with the stock bolts then to upgrade bolts and not resize...I no no, i sound like the stingiest person right now, but im trying to keep my eye on the dollar here since this is just a temporary motor until i built the stroker...bone stock bottom end, motor had less than 150 clicks on it- bearings, rings, and crank all look and measured out close to perfect!
 

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so its probably actually safer to keep the rods the way they are now with the stock bolts then to upgrade bolts and not resize...I no no, i sound like the stingiest person right now, but im trying to keep my eye on the dollar here since this is just a temporary motor until i built the stroker...bone stock bottom end, motor had less than 150 clicks on it- bearings, rings, and crank all look and measured out close to perfect!
Myself personally i dont like stock rod bolts in anything,, but thats just me,,, i know you are trying to save a dollar but be carefull that dollar you save might cost you a hundered,,, seen it happen
 

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im only thinking this since i plan on keeping the rpms down...not much more than 6k, at most 6200 id say..I guess Ill see when i do it
 

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Take these guys advice, they're right. Change the bolts and get the rods resized. Small expense compared to the possible damage that could happen otherwise...................Hell, I'm even having my rods redone..........New rod bolts, rods resized. Carrillo H-beams with ARP2000 bolts.............Old ones are SPS Carr, but are done...........
 

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o.p. never stated what actual exact rod or engine this is.....

but a totally stock rod aint suppose to spin up to his so called "safe 6000 rpm" ...that he is targeting....!!!!!!

?........SAVE MONEY BY DOING IT RIGHT THE FIRST TIME....
 

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All these engine builders aint gonna like this but.....RUN IT!

But I do agree with the bolt change deal, if you replace OEM bolts with stronger fastners with more clamping loads such as ARPS's, it will distort the big-end, so run the OEM bolts and keep the R's low (below 6K) and have some fun till you get that bad boy stroker done, hell I bet if you tried to blow it up you couldn't, but dont..lol

Chow>Cp
 

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All these engine builders aint gonna like this but.....RUN IT!

But I do agree with the bolt change deal, if you replace OEM bolts with stronger fastners with more clamping loads such as ARPS's, it will distort the big-end, so run the OEM bolts and keep the R's low (below 6K) and have some fun till you get that bad boy stroker done, hell I bet if you tried to blow it up you couldn't, but dont..lol

Chow>Cp
The reason i think i might just run it the way it is is because look at alot of cars out there running hard on stock bottom ends- guys in fox bodies, LT1 and LS1 camaro's, magnum mopar smallblocks with stock bottom ends...the list goes on...and they are putting more to those things than I know I will be...this is the only reason why i get the reasoning for this

The amount im going to spend to get new bolts, get the pistons removed so they can be checked and bored on the big end, and then pistons reinstalled (these are press fit stock stuff), im going to be in alot of cash...if i was to ship it somewhere else, id still be in for the shipping back and forth....not exactly budget like i planned since this motor will only be temporary until the stroker goes in

The engine in question is a mopar smallblock LA...
 

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I've tried it (eons ago), here's what happens. I even used some magazine's instructions about leaving 1 side torqued while replacing the other, blah, blah. The locating diameter on the ARP bolts was unique; it was knurled, while the stockers weren't (SBF). Theoretically, this shouldn't matter, but in the real world, it did; as the ARP bolt moved thru the rod, the knurl actually removed some material, I could see the tiny chips. As a result, the way it located the cap was not exactly the same, and the cap ended up being offset longways just a hair. Not good, since a hair is about the same thickness as the oil film.

However, I have replaced a stock bolt with an identical one with no issues.
 
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