What is the consensus concerning crack cap rods with arp bolts? Will the bore in rod get shorter in the vertical? Or does the nature of the crack keep the horizontal joint from slipping? Thanks

quote:

Originally posted by fasterat:
What is the consensus concerning crack cap rods with arp bolts? Will the bore in rod get shorter in the vertical? Or does the nature of the crack keep the horizontal joint from slipping? Thanks

With a standard off the stock bolts, a dial bore gauge can better answer this question Sir.

I'd have to see it to believe it, either way. Consensus wouldn't suffice.

With the increased clamping force of an ARP fastener, you should always recheck bore size after replacing an existing bolt/stud with an ARP. This is true with rods, mains even cylinder bores.

i dont know.but why use that rod type

Fasterat. Educate me on these rods. I may be mistaken but are these rods like the ones use in the Ford performance Mustang engine.

Slickster, yes. I despise these rods. I’m building a 6.1 Hemi for an acquaintance and those are the factory rods. He’s financially unable to purchase good rods at this time. The bearings have.001” too much clearance and I m wondering if arp bolts would close the gap any. With this design I wonder if it’s possible. Currently the clearance is .004” using bore gauges and in my humble opinion it’s too much for street engine.

I think the LS engines used cracked rod caps too don't they?

By closing the gap, wouldn't it just be squeezing it out of round in this case? Possible to get different bearings?

This topic raises some good questions. Not a fan of cracked cap rods, but I hadn't thought about resizing them until now. Is that even possible?
Resizing rods used to be highly recommended any time you replaced rod bolts, because of the pressing involved, distortion from interference fit, etc. I haven't always resized them, some rods measure out just fine after pressing in new bolts.
In this case, (too much clearance with cracked cap rods), I don't know what options there are, other than undersize bearings?

I can just imagine the cost saving project meetings on this one....a great and stupid idea all wrapped up into one. Great for production and saving machining the cap ends.....dumb if you want to ever rebuild it. Pretty ingenious but not a hot rods best friend for sure.

I took 16 Gen4 LS rods to the machine shop and a set of 8 ARP bolts. I wanted 1 good set of rods. Ended up with 10 that passed. 8 are in a motor that made 570hp the other 2 I gave to the machine shop and 6 in the trash. I got a set of Oliver Rods for the next motor.

Cracked cap rods were great in a 2-stroke outboard engine, but those were roller bearings and clearances don't mean much.

Clevite, makes an undersized bearing but as with everything else in today’s world there are none to be had. I guess I’ll stack this pile of parts next to the other 3 piles of engine builds awaiting parts for completion.

quote:

Originally posted by BG7X77:
I can just imagine the cost saving project meetings on this one....a great and stupid idea all wrapped up into one. Great for production and saving machining the cap ends.....dumb if you want to ever rebuild it. Pretty ingenious but not a hot rods best friend for sure.

I was complaining to a friend of mine once about how the stock transmission pan on my dually had no drain plug - he replied "GM makes 10 million cars every year.... think about how much more money they make when they save $.50 here or $1 there".
I think about that all the time!!

quote:

Originally posted by BD104X:

quote:

Originally posted by BG7X77:
I can just imagine the cost saving project meetings on this one....a great and stupid idea all wrapped up into one. Great for production and saving machining the cap ends.....dumb if you want to ever rebuild it. Pretty ingenious but not a hot rods best friend for sure.

I was complaining to a friend of mine once about how the stock transmission pan on my dually had no drain plug - he replied "GM makes 10 million cars every year.... think about how much more money they make when they save $.50 here or $1 there".
I think about that all the time!!

No doubt. When I worked in electrical automotive industry tenths of a cent on a terminal crimp was real money. Now take those 10 million vehicles and multiply by how many terminal crimps are made in total. It all adds up.

Problem solved. Using my abrasive blast cabinet I found that using the right grit I could blast both of the horizontal joints of the cap and rod and after a cleaning when assembled the vertical measurement showed that it lost .0009” in diameter. The parting line was still almost invisible and it mated together like it did prior to my science experiment. So technically, crack cap rods can be resized.

If your goal is to recondition or re-size a "cracked cap" connecting rod, there are several bearing manufactures that offer an oversize bearing that allows you to hone the bore bigger so you just use the oversize o.d. bearing like a regular bearing. These bearings became available about 1 hour after cracked rods came out years ago.

Oh I’m aware of the undersized bearings. I’m also aware that not one of the parts wholesalers I have accounts with have any undersized bearings available. They barely have any thing available.

How about the dealer I know guys used to get 001 bearings from GM

I would also be concerned with blasting them I understand the idea but how can you be sure the consistency