A blown head gasket really pours the junk down holes, but just running high boost & drive pressure allows combustion seepage.
Production also under taps holes and worn taps don't leave a high quality hole.
problem is you don't really know what's in the hole until you run a tap down there.

 

see 98.5 POS's thread on head stud retorque

 

I did and here is what he said

 

sure it was the right tap?!?!? something went wrong there............


With the correct thread and pitch on the stud correct the thread and pitch on the tap correct......... there is no way 125ftlbs should "pull" threads. So thing was very wrong there.


and if you drive the stud into the bottom of the hole and torque it against the end of the threads it will likely pull threads when you try to remove it, not while you're torquing.

Something doesn't add up there.

 

thats what i thought


now i was instructed when i installed mine to run them all the way down with my fingers, then back them out 1/4-1/2 a turn, then torque it down. i did this with no problems

 

i thought the stud was only supposed to be in the block tight enough to keep it from backing out? and the bolt on top of the head is the one you torque down? didn't they discuss this in that thread?

 

Thats what I've learned about studs too........... its not the stud that gets torqued it the nut on top that divides the torque and clamping force over both ends of the stud..........but thats neither here nor there if the ARP directions say different.


BIGBLUE If you don't have one already

I have a 3 flute bottoming M12x1.75 but its only 3 1/2" long. an extention will have to be welded on...........if you can get a measurement from your head on how long the extension needs to be I'll get one welded on. Factor in the 3.5" for the tap from the bottom of the hole and tell me what length extension. I'll get a 3/8s drive welded on, and mail it down for you to use. then mail it back and I'll probably be ready to use it. I'll be studding my head soon too.

 

I agree with BigBlue, why go to all the trouble of installing studs half a$h, then only to turn around and have to bottom tap them again in 6 months. I say tap them!

 

The problem with welding an extension onto a bottoming tap is that with the head on, the tap will have to be about 8” long. It is not possible to get a tap that long into the head under the cowl near the firewall. Having a two-piece tap that can be separated is needed.

 

.........hmm interesting, good point didn't think of that.


OK, bigblue if you can get me exactly the length needed. I'll see about getting on of my machinist buddies to make a female/male square drive extension.

 

What is the size of the tap where a tap handle would go? Get one (or make one) so its 3/8" across and use a 3/8" extension upside down on it. Could still use a tap handle then.

 

The tap I pictured a few posts ago worked on mine?

 

DANG, your smrt. good idea. I'll go check...............




.........its a 1/4" exactly. Nice job Tate.

 

Blue the total length of the tap with the extension welded on is 8.25"
Granted this is for a 12v but I'm sure you can just measure the longest stud to find out what you need. Removing the large rubber plugs in the cowl allowed me to get the tap in.

 

I believe the 12 valve must have more space under the cowl. Here is a picture of my 24 valve with a measurement of 6 ½” between the top of the head and cowl. I had to cut the sound insulation away and pry up the cowl to install the head studs where the rubber plugs were not near enough. My 6” tap will fit under the cowl but an 8” tap would not. The two-piece tap is needed.