Weird rod bolt interference

[zztot]

I am having 2 liter 6 built. Most likely unneeded ARP rod bolts were. Everything went together but on very last cylinder (#5) something interfered with rotation. It turned out to be a rod bolt projecting further than all others once torqued….. like 3+ or so threads.
It hit the bottom edge of the cylinder .
Once it had a few thousands ground off everything cleared and it rotates freely.
Question……WTF?
Seriously what’s going on?
Kind of spooked so looking for explanation…
Any ideas???
Thanks

[PeteKz]

Strange. The ARP bolts should all be the same length. Pull that rod and measure the bolts. ARP provides a spec for bolt length.

[Dpmulvan]

If it’s not the bolt, my guess would be it’s got to be that rod, rod bearing or crank journal.

[stownsen914]

Any chance you got one 2.2-2.7 rod bolt in your set? They're similar but longer. 2.0L rod caps are shaped differently than 2.2-2.7 rods so have a shorter bolt.

[Henry Schmidt]

Originally Posted by stownsen914

Any chance you got one 2.2-2.7 rod bolt in your set? They're similar but longer. 2.0L rod caps are shaped differently than 2.2-2.7 rods so have a shorter bolt.

Good thought but the 2.2 (70-71) and 2.4/2.7& 3.0 (72-83) bolts are different. ARP never made a rod bolt for the 2.2 rod. The 70-71 rod was unique to the 2.2 and ARP never saw a big enough market to make a bolt to fit that rod.

[stownsen914]

Ah gotcha, makes sense.

I'd want to pull the bolts out of the #5 rod and see what's different about the offending bolt. For example, since it's obviously different, maybe the widened shoulder in the middle of the bolt is different too. Could just be a bolt that's meant for some other application but got mixed in with OP's set for whatever reason.

[zztot]

ARP has tech assistance on line. they feel incorrect bolt was packed based on dimension.
Sending me a new one.

[Krieger914]

You definitely need more than a few thousands clearance in there.

[zztot]

So appears as though we have a satisfactory resolution.
I contacted ARP through their online helpline and explained the issue.
Very quickly they told me wrong bolt length apparently got packed with set.
A new bolt was sent overnight.
Here’s the best part………once installed and torqued, only one thread was showing just like all of the others and unlike the three or so that were showing on the other bolt. Dimension was not off as far as originally reported but something definitely not right.
Thanks for the input.

[zztot]

So one more question Henry.
Based on issue wanting to confirm (for builder) that .5mm/.020 clearance between rod bolt and base of cylinder is adequate?
Thank you

[PeteKz]

If the rod gets loose enough or swings wide enough to take up .020" of clearance, you will have much bigger problems.

[zztot]

Pete:
I believe (with my limited knowledge) that to be true…….The question was asked of me but could be bc I rely on this forum for input on the build to keep us in current good practice. Thanks to all for continuing help in keeping me out of the woods.