Whats the possible problem if you use ARP rod bolts without resizing the rod? I had ARP rod bolts put in mine...

 

Havnt you read the hundreds of "I used ARP rod bolts and melted down my shortblock chernobyl-style" threads? I havnt found them either.

but to answer your question, there exists a possibility that the bolts may deform the big end of the rod.

 

While were agonizing over these details, I took another look at this pic showing the "alignment dowel" that I referenced previously (and which fouls the slightly larger OD of the ARP bolt on the left) I now realize it doesn't go all the way through the cap, and the only thing it might align is the bolts, so they will sit straight if the engine plant drops them in place before running them down and machine-torquing them on the assembly line.
If this is true, I assume we just yank the sleeves before installing the ARP bolts?
EDIT: Pic File is too big. What it shows is that the ARP bolt has a slightly larger under-head radius and a larger shank just below the head, which is a few thous. larger than the ID of the little sleeve, so will not install into same.

 

Installation is simple. Remove the old bolts and sleeves, add oil to the threads and torque to 50 ft/lbs. We have sold thousands of rod bolts and use them ourselves with no problems.

 

The difference is that katech (or A1 who manufactures them) paid close attention to keep the bolts as close to the stock size and shape. Since theyre nearly identical to teh stockers, they shouldnt need any resizing. Theyre a very high quality piece with extra engineering however theyre also more expensive because of this.

The real question is wether or not the extra engineering is critical to those that simply torque down the new bolts and drive. Many people have done the same with ARP bolts. Its just that Katech as a company is willing to tell you that you can simply swap and fly whereas ARP, to cover their asses, suggest that you check the roundness of the rods afterwards. The difference in price that you pay for the more expensive Katech bolts gains you piece of mind that the company outwardly states that you can simply swap. ARP does not make this claim no matter how many people have sucessfully done the same thing with their bolts. Whether or not its worth the added expense is up to you. Also to be noted is that while either ARP bolt is sufficient for high RPMs, the katech bolts are rated a bit higher in terms of tensile strength.

This is based on my research throughout the popular lsx forums. I have not done the swap myself. Im currently content using the stronger 01+ stock bolts since I dont spin the motor up very high, nor very often. However, I would not hesitate to use either the ARP High Perf (cheaper, not the PRO) or the Katechs, which are undoubtedly the finest rod bolt available for the lsx engine.

 

Well I figure since I have them I will try, and since I have been a Tool and Die maker for over 10 years I will take the proper measurements of the stock Rod bolts and the ARP Pro series and see if there is any differences, if not I will install! I will update in the next few days for those who are as curious as I am...

 

This has been implemented very successfully on a number of motors. Remember you are dealing with a "cracked" Rod very different from a "standard" rod. there will be no cap shift. Each cap is unique to the repective rod, like a puzzle piece. see link to pics on my first post. I would be very suprised in any signifigant changes to the rod when its torqued down.

 

Not that I don't beleive you or your first post, just want to measure the bolts to see if there are any differences. I already beleive that the rod won't go out of round...

 

the ARP pros are definately longer than the stockers.

Stockers don't go to the edge of the threaded hole. ARP Pros go all the way.

I've ran the pros without resizing quite successfully for the last 4 years

 

Thanks, I was waiting for somebody with first hand expereince!

 

Exactly. As long as the new bolts are putting the same stress on the assembly, there should be no problems.

 

 

The rods can be resized with special .002" oversize outside diameter bearings.
Thing is there are no std. size bearings, only .010 under from what I know of.
Unless someone makes a std bearing there is not much you can do with your rods if they are out of round.

Katech is the way to go, ARPs are longer and heavier, while the Katech mimic stock bolts very closely.

Lingenfelter uses them in their performance builds.

 

I did a engine build last year with stock rods and the arp pro none wave lock rod bolts. My engine builder was concerned about big end rod distortion. He checked three different rods. Also torqued the bolts three times to make sure we had enough stretch according to the instructions that came with them. There was no distortion on two rods and like .001 on the last rod.

 

Ideally I would prefer not to replace rod bolts without resizing.

 

In light of predator-z's above testamony, how would you accomplish resizing? You'd go through the trouble of having the crank ground to accomodate the .010 smaller I/D bearings? Seems like WAAAAAAAAY more trouble than anyone would ever go through.

 

Any updates...? I'm curious if you found any measurable difference with the Pro Series bolts...I measured the ARP 8740 series and found all measurment were dead nuts on of the stock bolts...

 

I would like to see a update myself.
I have used the ARP cracked series rod bolts in 5 or 6 H/C cars with very good success. I never measured anything though, but all the cars still run and run well.

 

UPDATE: ARP Pro series measurements
47mm below head
56mm length total
20.85 thread length
9mm diameter for 6.2mm from below the head to where it tapers to 7.74mm until the thread diameter which is 8.9mm

 

Stock bolt measurements:
49.7mm total length
42.7mm length below the head
18.3mm thread lenght
8.34mm diameter below the head
8.9mm thread diameter
sleeve measuements:
7.3mm length
8.47mm inside dia.
9.45mm outside dia.