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[hrdtail78]

I have noticed that some combinations will only yield about a 1/2 inch of engagement.  On bigger builds and high compression I have been taking the time and going with the S&S alternative longer bolts and have been getting about 3/4's of an inch of engagement.  BTW  I like to use stock studs.

This has caused me no problems.  My question comes about because sometimes I do things with the best intentions but in reality.  It just doesn't matter.  Has this been a concern for anybody else, or has anybody else address this?

S&S head bolts are $99 for the set.  They are actually on the cheaper side of things out there. 

TIA

[HD Street Performance]

Jason
Be careful doing this with heads that have been milled quite a bit. I have seen the stock bolts bottom out. May have been just the particular case, a 120R, but worth a few seconds of a measurement with calipers.

[Phaq2]

Jason, Jim@ Mega Flo noticed had the same concern on my recent 124 build and opt for the S&S head bolts. You might want to get more details from him the next time you talk to him.

[FlaHeatWave]

The rule of thumb used to be, thread engagement equals to the diameter of fastener ( say 1/2 inch Bolt and you have one half inch of thread engagement) is more than enough, it will give all the mechanical integrity that can be had. Any more engagement is superfluous...

[hrdtail78]

I was always taught that the rule of thumb was 1.5 the diameter of the bolt.  A 1/2-13 bolt wants 3/4 engagement.

[hrdtail78]

The above pic is with stock length bolts.   According to my ROT I need a minimum of .5625 engagement.

[hrdtail78]

I am dealing with 5.040 S&S cylinders on this one that puts studs below the deck.

[hrdtail78]

Jason, Jim@ Mega Flo noticed had the same concern on my recent 124 build and opt for the S&S head bolts. You might want to get more details from him the next time you talk to him.

Jim is a great motivator to measure everything, and don't assume anything.

[HD Street Performance]

 
Think you nailed this.

[FlaHeatWave]

I was always taught that the rule of thumb was 1.5 the diameter of the bolt.  A 1/2-13 bolt wants 3/4 engagement.

Standard 1/2" nuts are not anywhere near that thick...

[hrdtail78]

Standard 1/2" nuts are not anywhere near that thick...

Not disagreeing but there are a couple of other considerations.  Bolt application, is it tension or shear loaded.  In a pure shear load.  The nut has a very different job than in a tension application.  Also with nuts.  There is minimum thread that needs to stick out of the nut.  Material of hardware and the material of the blind hole.  I wouldn't think that a 3/8 cylinder stud would last very long only having 3/8 thread engagement into the cast case.  My ROT of .5625 doesn't work here either.  Stock studs usually have 1.25 of thread engagement into the case, and it can still pull out or pull the case deck up around the stud.

[wfolarry]

This might help explain it better than me:
https://www.fastenal.com/en/78/screw-thread-design

[Mr. Warlock]

This might help explain it better than me:
https://www.fastenal.com/en/78/screw-thread-design

1 1/2 times the diameter for aluminum.