Anyone have an ARP part number for head studs on a Predator engine. Called ARP and did not get a lot of help, maybe the guy was having a bad day but did not get far. Have the set that came with the heads from Indy but the coarse threaded end that goes into the block is VERY short and would prefer something with a longer thread on the block end for more thread engagement into an aluminum block. Hoping maybe we just got a bum set but these are really short on the head end and prefer something with more thread on that end. Any help is appreciated.

FWIW the coarse end has only .650" of thread engagement.

Kb block or Indy? Give the dimensions of the "above deck" portion of the studs to ARP and then tell them how long you want them to go in the block. 2.5-2.75" usually with an aluminum water block.

You might have to order individual studs

Block is a World piece. And looking like we will need individual ones at this point.

Al

when you get the correct Part #'s can you update this tread or send me a PM.


Thanks
Joe

7/16, or 1/2

Al, Both of my Predators have World blocks. I just called Todd Marsh and ordered them, but they were off the shelf parts. Maybe you are after something special?

.650 thread engagement for a 7/16 stud should be plenty. Engineering spec is usually 8 threads of engagement for 100% strength. Rule of thumb is 1.5 diameter of engagement for full strength. So .650 thread passes both of those rules.

Well while it MAY be enough from an engineering standpoint IF it had 8 threads fact is these only have 7 full threads of engagement. We are wanting more thread engagement considering it is an aluminum block, which is designed for a longer thread. The 6 long bolts on the center of the deck are the only ones that are .650" in length, the rest of the studs are .850" or .900" in length on the block side. So we are looking for something closer to .850" or more for those studs.

They are 7/16" studs. Just an NA motor and feel this is more than adequate for what we are doing. If I scrounge up a part number will be happy to share. Will be headed over to an big engine shop today to see what they have. Only concerned about the 6 center studs really.

I have a whole set of regular ones for a KB block and a set of 625+ 7/16 studs for predators also.

Let me know if those might work for ya.

Well some have been located locally that we are happy with. So thanks for the help gents.

be interested to hear some dimension on the ones you have...

I personally like the stud to bottom out in the hole on aluminum blocks. On some blocks, where the threads haven't been deep enough to allow the nub on the stud to bottom out, I have dropped ball bearings in the bottom of the hole, for the stud to bottom on

Exactly what we are after Monte, a much thread engagement as possible being that it is an aluminum block.

Wow, my Hemi blocks use 2.75" of thread engagement. 1.00" or less seems odd to me in an aluminum block.

Al,what did you end up with?

Found some studs that have 1.125 of thread on the block side and we feel much better about it now. Sorry no part number we raided the drawers of a well known Comp Engine builder to find these

You may have found what you need, but is info from our engine.

Head stud info:

KB (4)-52211 7/16" x 6.500
KB (6)-52205 7/16" x 6.980
KB (8)-52212 7/16" x 4.180
ARP (16)-44201 7/16" x 3.540
ARP #2008531 head stud washers
ARP #3008333 head stud nuts

My memory might be off, block might be 1.75" and not 2.75" of thread.

efi dart,if you still have the head studs for kb block for predator heads or know part number please give me a call 502-350-7726.i need them bad.i called ken black three weeks ago but he was to busy to take my order or call back....

I had KB make mine because the are 1/2" in the block 7/16" from the deck up.

Grip length is 4.575" for the 3 center head bolts. So you need 1.00" fine and 1.500" coarse.

I think you can use a 7.00 inch stud with 1.00" top (fine) and 1.50" bottom (coarse).