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Sat Sep 24, 2011 8:31 pm

I'm assembling an engine with some chinese 4140 rods, they have some knock off rod bolts that are 3/8 and stamped 8740 on the head. I usually use ARP bolts, but I'm gonna run these bolts if I can figure out the torque/ stretch spec.

Can I use ARP data or would you just see how much torque it takes to get them to just under .0047 stretch or is that even the proper stretch?

Sat Sep 24, 2011 8:37 pm

who knows,ask him. or his brother rong.I would think a 3/8, 8740 should go 48-52 with molly.but shit happens, better find out.or get some more bolts.

Sat Sep 24, 2011 9:16 pm

Torque them up 10% shy of ARP spec and check the stretch
If they don't have nice machined ends like arp then you can't really check stretch, toss em

Were the bolts torqued and was there lube on them as recieved?
If not how did they hone the rod?

Sat Sep 24, 2011 9:22 pm

modok wrote: Torque them up 10% shy of ARP spec and check the stretch
If they don't have nice machined ends like arp then you can't really check stretch, toss em

Were the bolts torqued and was there lube on them as recieved?
If not how did they hone the rod?

They are descent looking. They are torqued up, I guess I can see what they are torqued to huh, I haven't loosened one to see if it is lubed.

Sat Sep 24, 2011 9:25 pm

ok cool

you can mark the position of the head and loosen it, then see what it takes to get it back to that same spot

not high tech, but the more you know the better

Sun Sep 25, 2011 6:58 am

some rods are sized with mule bolts. and you can always dimple the end. remember with moly it takes 3 torques to get to the corect torque.I doubt that is done when the rods are sized.

Sun Sep 25, 2011 7:40 am

mark tucker wrote: some rods are sized with mule bolts. and you can always dimple the end. remember with moly it takes 3 torques to get to the corect torque.I doubt that is done when the rods are sized.

who knows, I'm just gonna stretch them and see if they hold up, I'm guessing I'm gonna have at least 1 fail on the stretch and have to order some good bolts.

Sun Sep 25, 2011 8:00 am

SamT wrote: mark tucker wrote: some rods are sized with mule bolts. and you can always dimple the end. remember with moly it takes 3 torques to get to the corect torque.I doubt that is done when the rods are sized.

who knows, I'm just gonna stretch them and see if they hold up, I'm guessing I'm gonna have at least 1 fail on the stretch and have to order some good bolts. just remember that it dosent have to break to be bad or damaged, you can feal it when it is past it,s yeild strength in most cases.but some do snap crackle pop.

Sun Sep 25, 2011 10:22 am

mark tucker wrote: SamT wrote: mark tucker wrote: some rods are sized with mule bolts. and you can always dimple the end. remember with moly it takes 3 torques to get to the corect torque.I doubt that is done when the rods are sized.

who knows, I'm just gonna stretch them and see if they hold up, I'm guessing I'm gonna have at least 1 fail on the stretch and have to order some good bolts. just remember that it dosent have to break to be bad or damaged, you can feal it when it is past it,s yeild strength in most cases.but some do snap crackle pop.

I will be using a stretch gauge and if they over stretch, in the trash they go!

Sun Sep 25, 2011 4:43 pm

Having seen and used "one" set of AA rods and how crappy those bolts were I was much more sure of the EMPI 8740 bolts. The AA bolt heads didn't even all fit the socket and had to be modified....never again.

RC

Sun Sep 25, 2011 5:00 pm

The worst I ever saw was pro-comp
the bolts were rough machined, and they didn't torque the rods or lube the bolts.
They were torqued to like 25 ft-lb out of the box, and when I took out the bolts the threads jammed and got tore up.
When torqued, the big end assumed a kind if square type shape :lol:

It can't be worse than that

Sun Sep 25, 2011 5:05 pm

well I was balancing some AA pistons today, they were as close as any Mahle pistons I have seen. Actually the pistons alone were within .3 grams, but the wrist pins were .5 grams difference between them, after juggling the pins around I only had to remove material from 1 piston to get within .1 gram.

These AA rods are another story, 7 grams of difference in total weight. Guess I'm gonna have to build a jig so I can balance the small end.

For reference I checked a set of CB Unitech rods and they were within 2 grams total weight. I read that .5 gram is acceptable.

Sun Sep 25, 2011 6:09 pm

I forget what the total weight difference was on the AA rod set we tried but it was very close....like 1 gram or less....I really forget. :oops: When doing small/big end though there was a large amount of difference to compensate for. It was the most difficult set I ever balanced. From the lightest untouched small end to the worst required a major almost rod polishing effort so as not to effect rod integrity. Like I said.....never again. I couldn't charge the customer for the amount of time I put into that set of rods because he went with them based on my idea that it was worth a try.

Don't even want to discuss the OEM rods for that engine that were supposed to be a balanced set but had about 8 grams total weight difference and the lightest rod had the heaviest small end.....what a nightmare.

Go figure....

RC

Sun Sep 25, 2011 7:42 pm

Yesterday I torqued my AA 3/8" bolt I-beams to about 42lbs with blue loctite.

Sun Sep 25, 2011 8:06 pm

why the locktite? you think they gonna come loose?
:P

Just weld them nuts in place, that's fix it even better

Sun Sep 25, 2011 10:48 pm

modok wrote: why the locktite? you think they gonna come loose?
:P

Just weld them nuts in place, that's fix it even better

No, but I'm using a beam type torque wrench...not real exact so I just wanted to play it safe.

Sun Sep 25, 2011 11:52 pm

bomberbaja
There is nothing wrong with a beam type torque wrench, they never need to be recalibrated. the only thing that clicker type have over beam is they are faster to do V-8 head bolts, I have both types and on a ACVW I will only use a beam type, with a beam type you can see when some thing is wrong. now If some one would make a BT with a ratchet head. I would like to have a 3/4" clicker type for gland and axle nuts

Casey

Mon Sep 26, 2011 3:48 am

bomberbaja wrote: modok wrote: why the locktite? you think they gonna come loose?
:P

Just weld them nuts in place, that's fix it even better

No, but I'm using a beam type torque wrench...not real exact so I just wanted to play it safe.

There are some pretty good builders that do locktite rod bolts.

I just think it's redundant because if the bolt is loose enough to need locktite, the rod will self destruct anyway.

Rod bolts good enough that they don't need locking have been around since WW2, but many kept doing it till the 70s. Some still do it today.
Can't argue with tradition

Mon Sep 26, 2011 12:59 pm

Just put a dab of JB Weld on the rod bolt threads....It goes hand in hand with JB welding the case halves together. :lol: :lol:

NOTE: THE ABOVE IS MEANT AS A JOKE

Mon Sep 26, 2011 1:03 pm

HAHA!! another Sig. line quote for Darth!