Rod Bolt Length

I am finally getting to start building my engine and I am measuring my rod bolts (brand new L-19 GRP rods) for a reference. I figured now is a good time to do it because they haven't been run yet. Just picked a rod out of the box took the bolts out and they are .005" different Am I splitting hairs or is this a problem. I would have thought that ARP had better QC than that. I assumed they would all be the same but I guess not.

I'm going to continue checking them but I figured I'd ask now.

Should I be concerned with that .005" or not.

Thanks
Corey

 

Finished checking all the bolts and here is what I found.

All fall into the following

2.450" to 2.444"

.006" variance

Any opinions or advice would be great.

Corey

 

i never knew anyone ever checked the total length of a rod bolt down to the 1000th. as long as they don't bottom out, i wouldn't think it would matter if there were .100 difference. just my 2 cents

 

It should seem quite apparent that I have a lot of time on my hands I was checking them so I have something to compare too when the engine comes down again. (to see if they have yielded etc)

From your reaction it would seem I am in fact splitting some hairs.

Thanks

Corey

 

If you are intending to check bolt stretch, I don't think you are splitting hairs. Recently we had some bolts break, so now I am checking the lengths before and after torqueing; it would definitely be useful if they were all the same length. This would make it easy to check the stretch on each bolt, and would also give me an indicator of when the bolts were starting to permanently deform.

 

Bolt Length

I was also hoping they would be the same length because now I will have to chart each rod and its related bolts in order to do this correctly.

But like I said, lots of time.

Corey

 

Maybe you could engrave the last 2 digits of the length on the head of the bolt for quick reference no plotting and having to keep track of where they go.

 

Bolt length

Not a bad idea, only problem is I can barely see a micrometer, engraving that small a number on a bolt might be a problem

Corey

 

You need to use a stretch gauge to check this. I think GRP can set you up with one and also tell you how much stretch you need to see at proper torque. Doug

 

Rod Bolt

Thanks Doug, I actually have a stretch guage, As Ken said, I'm tying to get a starting point so when I take the engine apart I will know if the bolts have permanently deformed or not.

Thanks
Corey

 

The variation in length is not at all unusual, what you need to do is to record the length of each bolt prior to installation and record that number. After use when you remove the bolts for service if the bolt has stretched past .001 then the bolt has seen elastic deformation ( its stretched ) and should be pitched.

Also on the L-19 bolts it is very important to not just torque the bolts but rather to use bolt stretch ( if at all possible, I know some rods the holes are blind ) and use the recommended stretch to ensure adequate clamp strength.

Many people also feel that on new rods and bolts it is a good idea to torque the bolts several times to seat the bolts and the threads prior to final assembly.

Its also a good idea to keep the bolts oiled as they are very susceptible to rust resulting in fracture.

 

Bolt Length

Looks like my engine log book is just going to have a couple extra pages in it.
No problem, I'd rather spend the extra time logging everything than have a failure because I rushed through something.

Thanks for the info

Corey

 

Wouldn't it be pretty easy to thread a steel block and thread the bolt thru and surface grind the end? I'm doing that right now