head studs

[70wayfarer]

screwed in the arp head studs into the block, slipped the head gasket on and dropped the heads in place. all good so far. lubed the washers and top of studs and screwed the nuts on. here is the problem. all the long studs are short about 3-4 treads below top of nut. all the short ones have about 3-4 threads above the nut.
they are eddy rpm heads. has anyone encountered this before. either the studs are short or eddy has not milled the nut seats deep enough?

 

[jimjimjimmy]

is the picture of torqued or finger tight nuts ?

 

[70wayfarer]

nipped up with socket. there should still be thread above the nut regardless.
thought about backing the stud out of the block a tad, but this will see 18 psi boost, so me think not.

 

[SGBARRACUDA]

I used a set of ARP head studs on my Indybrock heads but they were purchased from Indy.
The Indy part number is 360-H4-17. I don't know what the equivalent ARP part number would be but mine fit better than that and are actually a bit long

 

[70aarcuda]

http://www.summitracing.com/parts/arp-144-4005/overview/make/chrysler

part number says it is correct....

 

[nm9stheham]

ARP Kit number 144-4005 is the PN listed for RPM Performer heads.

http://arp-bolts.com/kits/Make.php?_Make=200&_EngModelID=*

Some very rough numbers on the stud axial force needed to tear out the block threads:
0.8" thread engagement in block: roughly 2500 lbs
1" thread engagement in block: roughly 4300 lbs
Stud preload force: roughly 1000 lbs
Max force per bolt for boosted mean cylinder pressure: roughly 500-750 lbs

These are just numbers I would look at if looking at this myself; it's not guaranteed.

So with near 1" of block thread engagement, you have decent safety margin, over 100%. 0.8" thread engagement in the block has only about 50% safety margin. (But, my assumption on the effect of cylinder pressure force on the studs may be too conservative.)

Assumes:
- standard grey cast iron block (40 ksi yield) and ARP's 8750 steel (150 ksi or more yield)
- block threads are in good shape and pretty tight to the stud threads
My thread yield computations use this: http://www.engineersedge.com/calculators/thread_yield_and_tensile_strength_13423.htm)

 

[L4staero]

I had the same thing with eddy heads and the correct arp studs for the heads. It was down in the nut a turn or 2. I just run it although its a low power 318

 

[IQ52]

The studs I use are the 144-4002 listed for the W2 heads. If you want bolts use the ARP-144-3601.

 

[70wayfarer]

ARP Kit number 144-4005 is the PN listed for RPM Performer heads.

http://arp-bolts.com/kits/Make.php?_Make=200&_EngModelID=*

Some very rough numbers on the stud axial force needed to tear out the block threads:
0.8" thread engagement in block: roughly 2500 lbs
1" thread engagement in block: roughly 4300 lbs
Stud preload force: roughly 1000 lbs
Max force per bolt for boosted mean cylinder pressure: roughly 500-750 lbs

These are just numbers I would look at if looking at this myself; it's not guaranteed.

So with near 1" of block thread engagement, you have decent safety margin, over 100%. 0.8" thread engagement in the block has only about 50% safety margin. (But, my assumption on the effect of cylinder pressure force on the studs may be too conservative.)

Assumes:
- standard grey cast iron block (40 ksi yield) and ARP's 8750 steel (150 ksi or more yield)
- block threads are in good shape and pretty tight to the stud threads
My thread yield computations use this: http://www.engineersedge.com/calculators/thread_yield_and_tensile_strength_13423.htm)

backing the stud outa the head a turn will be enough and leaves over 1" thread in block. if i did that and used locktite in the bock it most likely be good.

 

[Treblig]

Rule of thumb on any threaded bolt/nut...minimum engagement must be at least the diameter of the thread. 3/8" bolt must have a least 3/8" thread engagement, 7/16" bolt should have at least 7/16" thread engagement. This holds true for Grade 3 thru Grade 8 bolts. Now the number of threads into the head itself will depend on what type of block cast iron or aluminum.

treblig

 

[justinp61]

I'd call ARP and get their thoughts. Never use loc tite on head or main studs, use only the recommended ARP lube.

 

[70wayfarer]

I'd call ARP and get their thoughts. Never use loc tite on head or main studs, use only the recommended ARP lube.

tech info that come in box with studs says loctite can be used if a more permanent for a permanent mounting of studs is preferred, but the studs must be torqued prior to the loctite setting up.

 

[raymond]

If you have more than an inch of stud threaded into the block, then it seems that some one has tapped the threads deeper than needed. An inch of thread engagement is way more than enough,

 

[nm9stheham]

If you could hold the studs while torquing the nuts, then locktite on the stud threads into the block would not make any difference since they are not turning and thus contributing any drag to the torque reading. But how to do that with a standard socket and torque wrench is the problem. Perhaps put the studs in with the locktite, set the torque on the nuts to an intermediate level with a box end wrench to squeeze the locktite into its final position, and then wait for the locktite to set up before final tightening to full torque.

And for the OP, my numbers are just very rough computations but it should show that backing out to 1" thread engagement retains a fair amount of thread strength. I used lower than average yield strength numbers for the iron block to be careful, and high end mean cylinder pressures (250 psi), but there are still a number of assumptions in any such computation. Actual peak combustion forces will be somewhat higher but also absorbed somewhat by the head material, so I just guessed that MEP would be good number to use. It would be interesting to understand more on that.

 

[IQ52]

Here is the next wrench in the pudding. What thread depth did you use when you had the block bored with the deck plate? If you used a deck plate, make sure you use that thread depth.

Otherwise yeah, just screw them in or out to whatever depth you want! Loctite, jello, motor oil or ARP lube, the bores aren't going to be round anyway.

 

[pishta]

I got a bag of lead shot.....backfill the stud holes to 1" depth...I never heard of studs being torqued.
ARP head studs for B/RB wont let a header sit flush. WTF?

 

[Treblig]

Here is the next wrench in the pudding. What thread depth did you use when you had the block bored with the deck plate? If you used a deck plate, make sure you use that thread depth.

Otherwise yeah, just screw them in or out to whatever depth you want! Loctite, jello, motor oil or ARP lube, the bores aren't going to be round anyway.

There's always room for J-E-L-L-O!!!!!!

treblig

 

[mech1nxh]

Here is the next wrench in the pudding. What thread depth did you use when you had the block bored with the deck plate? If you used a deck plate, make sure you use that thread depth.

Otherwise yeah, just screw them in or out to whatever depth you want! Loctite, jello, motor oil or ARP lube, the bores aren't going to be round anyway.

Thank You Sir !!!
I did not 'connect the dots' (as it were) between center line alignment !!!
...deck... cam ... crank.
Solves a 18 year old 'stuck in My head' Mystery block failure !

Apologies to the O/P , IQ52, & Honored Posters for the hijack !

 

[nm9stheham]

I got a bag of lead shot.....backfill the stud holes to 1" depth...I never heard of studs being torqued.
ARP head studs for B/RB wont let a header sit flush. WTF?

That seems like a good thought!