Milwaukee Midget

[Interested Observer]

MM,
If you have a dial indicator, you have most of a “stretch gauge”.  The rest can be cobbled up.  Use it!  Torquing the bolts using stretch is the best method, and often it is more expedient to make it a two-man operation, a torquer and a indicator operator.

Parenthetically, how did you arrive at the L19 material?  Do you really need that level of high strength and preload?  Its predilection for hydrogen embrittlement (stress corrosion cracking) is a bit worrisome. 

[Milwaukee Midget]

It's a 5/16 bolt.

The L19 is what Saenz uses as their standard bolt for a 6" A-series racing rod.  Given that this rod is typically twisted well north of 8 K on a significantly longer, whippier 1275 crank (3.2 v 2.45) with 3 mains, I suspect the forces put upon that combination warrant extra strength and clamping capacity.
 
Do I need it with a stiffer, balanced billet crank?  Maybe not. 

But on the other hand, despite my screw up, they didn't let go.

I might be able to save $100.00 by going with the ARP 2000.  But I would be kicking myself all the way home if one let loose.

I did look at the Aermet® bolts - so I can rationalize that I'm saving money by not using a bolt that has 20% more tensile strength than what I probably already don't need. 

[Rex Schimmer]

This is the ARP metallurgy info. Interesting reading.

Rex

http://arp-bolts.com/p/technical.php#p7TPMc1_4

[manta22]

ARP's quality control could be improved; I once bought a pack of ARP nuts that looked great but one had no threads, just a smooth round hole. 

Regards, Neil  Tucson, AZ

[Seldom Seen Slim]

I can imagine the response at Customer Service at ARP when you called them:

Neil:  "Hey -- what the heck is going on?  I got a nut from you that had just a smooth-walled hole through it -- no threads!"

ARP:  "Well, sir, that's not a surprise.  Did you specify that you wanted all of the nuts to be threaded?  If the customer does not specify we ship whatever we have in stock."

 

[manta22]

Well, Chris, at least they were all the same thread except one. Not a bad average. 

Regards, Neil  Tucson, AZ

[Milwaukee Midget]

Well, Chris, at least they were all the same thread except one. Not a bad average. 

Regards, Neil  Tucson, AZ

Yeah, but it begs the question.  If not ARP, then who would you turn to?

I'm unaware of another manufacturer whose fasteners are considered "go to", although I know the OEM MG/Rover K series head bolts are sourced out of Germany.

Actually, Neil, you know Europe better than I do.  Is there a German bolt manufacturer that might be a good alternative source?

[manta22]

Actually, Chris, I use new surplus AN/MS/NAS aerospace fasteners-- those I trust.

European fasteners are a mystery to me; maybe Pork Pie could give you a recommendation.

Regards, Neil  Tucson, AZ

[Milwaukee Midget]

Actually, Chris, I use new surplus AN/MS/NAS aerospace fasteners-- those I trust.

Of COURSE you do!

Where was my head?   

[Peter Jack]

Beware your sources Neil. A few years ago there was a flood of Chinese fakes hit the market. Hopefully that situation has been shut down.

Pete

[Milwaukee Midget]

Beware your sources Neil. A few years ago there was a flood of Chinese fakes hit the market. Hopefully that situation has been shut down.

Pete

I doubt if Neil's collection of high end retainers and ultraraium panels have any counterfeit issues.  If I'm not mistaken, a lot of it is NOS Skylab and Shuttle vintage surplus.

[wisdonm]

Will an SPS Carr Bolt used by Carillo fit? That's what MG LTD uses.

http://www.ebay.com/itm/NEW-5-16-CARRILLO-SPS-ROD-BOLTS-1-500-UNDER-HEAD-LENGTH-SBC-RACE-FORD-020314-13-/141188032823?pt=Race_Car_Parts&hash=item20df766937

[fordboy628]

It's a 5/16 bolt.

The L19 is what Saenz uses as their standard bolt for a 6" A-series racing rod.  Given that this rod is typically twisted well north of 8 K on a significantly longer, whippier 1275 crank (3.2 v 2.45) with 3 mains, I suspect the forces put upon that combination warrant extra strength and clamping capacity.
  
Do I need it with a stiffer, balanced billet crank?  Maybe not.  

But on the other hand, despite my screw up, they didn't let go.

I might be able to save $100.00 by going with the ARP 2000.  But I would be kicking myself all the way home if one let loose.

I did look at the Aermet® bolts - so I can rationalize that I'm saving money by not using a bolt that has 20% more tensile strength than what I probably already don't need.  

Fordboy's Rod Bolt Rules:

1)    Just my own opinion, mind you . . . . .

2)    Feel completely free to utilize your own "Rod Bolt Rules", at your own peril, and additionally, do not expect me to have a sympathetic ear if you experience a
       failure . . . . . .

3)    I base my rod bolt selection, both size and material, on the load I calculate for the maximum safe operating rpm I expect the engine to "reasonably encounter" in the
       course of operation.    I tend to be "Republican" about this, (that is to say "conservative"), simply because it is foolish to be otherwise.    I will always choose to use the
       next size up, when loads tend to be "marginal" for the fastener's load carrying capability.     Fastener designers think I am "too conservative" for using a design spec.
       limit of 80% of the yield strength.     DO NOT USE "Ultimate Tensile Strength" for your calculations, in spite of what anybody tells you!     BAD THINGS happen when rod
       bolts yield . . . . . .       A "small" weight penalty in terms of big end weight is the cost of "reliability", something I consider to be a performance factor . . . . . . .

4)    I ALWAYS discard bolts at a mfg's recommended cycle limit: ie, x number of hours of operation at y rpm, etc.
       OR, if the maximum safe recommended rpm has been exceeded.

5)    I also discard all rod bolts if ANY rod bolt fails ANY inspection process.    Such as:
       A)    Visual
       B)    Magnaflux, dye penetrant, etc, etc.
       C)    Micrometer length inspection.    Bolts MUST match the mfg's dimension & tolerance.   For obvious reasons.   Bolts that are long, are "stretched", AND HAVE YIELDED IN USE!
       D)    If I don't like the current moon phase . . . . . .  

The bottom line for me is:

I like to disassemble racing engines at whatever service interval.   A lot can be learned in the process.    I have done MANY racing engine "post mortems" trying to determine which part failed first.    Nobody is ever happy about those . . . . . .     The usual culprits are: rod bolts, other tensioned fasteners, valve springs, certain types of valves, steel retainers, and assembly and/or interference errors.    Not in any particular order.

A sensible engine builder weighs the cost of a set of new rod bolts ($$) Vs. the repair cost of a rod bolt failure . . . . . .($$$$)   A "Big Blast" can destroy "everything" below the head(s) . . . . .    

Caveat Emptor . . . . .
Fordboy

edit:

Midget,
The only way to do this properly is with a rod bolt stretch gauge.    We can use mine.
rodboltparanoidboy

[fordboy628]

Parenthetically, how did you arrive at the L19 material?  Do you really need that level of high strength and preload?  Its predilection for hydrogen embrittlement (stress corrosion cracking) is a bit worrisome. 

I'm sure MM did not choose the LD19 bolts.    When the various con-rod mfg's go ultra-light weight, the designers typically specify an LD19 bolt for "insurance" at the 5/16ths diameter.    LD19 AND 5/16ths diameter would not be MY first choice . . . . . .     Although I am willing to admit that they have been working reliably, the reality is they are a replacement item at EVERY rebuild, or else . . . . . .        A 3/8ths diameter bolt would have made the rod "slightly" heavier, would have been as reliable as a stone, could have been made from a less "sensitive" material, and could have provided more clamp load for a higher safe operating rpm . . . . . .   

It's a 5/16 bolt.

The L19 is what Saenz uses as their standard bolt for a 6" A-series racing rod.  Given that this rod is typically twisted well north of 8 K on a significantly longer, whippier 1275 crank (3.2 v 2.45) with 3 mains, I suspect the forces put upon that combination warrant extra strength and clamping capacity.
 
Do I need it with a stiffer, balanced billet crank?  Maybe not. 

But on the other hand, despite my screw up, they didn't let go.

I might be able to save $100.00 by going with the ARP 2000.  But I would be kicking myself all the way home if one let loose.

I did look at the Aermet® bolts - so I can rationalize that I'm saving money by not using a bolt that has 20% more tensile strength than what I probably already don't need. 

So we are all on the same page here.    The highest load the rod bolt "sees" is at "unloaded TDC rock-over", ie, TDC during overlap of the open valves.    Only the bolts (or the bolts and nuts, depending on your con-rod set), hold things together during the load reversal.    There must be sufficient tensile strength and "preload" for the fastener to withstand these loads, repeatedly.

Factors that contribute to the load the bolts must withstand, in order:

A)   Mass (weight) of the components; piston, wrist pin & locks, rings, entrapped or surface oil, con-rod and bolts above the split line, upper bearing.    I disagree with some
      other professionals on this, but IMO, this is what the load is.
2)   Acceleration forces dependent on the rpm range used, and also the maximum safe operating rpm desired.   (The "safety factor")
d)   Acceleration forces dependent on the con-rod length/crankshaft stroke length.    These are less of a factor at TDC and more of a factor when the rod is at 90 degrees to
      the crankpin.    This is not 90 degrees ATDC . . . . . .

Bolts are only glorified springs - you know what happens when you open the screen door too far or too many times! 

Exactly.

I believe I'll now cool my brain with an Oktoberfest, one of the last . . .   
 
Fordboy

[manta22]

Fordboy & MM;

"So we are all on the same page here.    The highest load the rod bolt "sees" is at "unloaded TDC rock-over", ie, TDC during overlap of the open valves.    Only the bolts (or the bolts and nuts, depending on your con-rod set), hold things together during the load reversal.    There must be sufficient tensile strength and "preload" for the fastener to withstand these loads, repeatedly."

That's a key point regarding fatigue life that is often overlooked or misunderstood. You NEVER want the tension in the (rod) bolt to drop to zero during the cycle. If it does, that bolt will fail VERY soon.

Regards, Neil  Tucson, AZ