Anyone know of a reasonable Bottoming Tap?

[JFaughn]

I've got all kinds of magnets , the sneakiest is a small round put into a piece of hose , then your not limited by over hang , also when I did my ETG probe I would spin it , it would fan out to catch more chips , then even trickier , is to put a piece of wire inside of the tube to get you to a spot nothing els will .
We have to be smarter than the problem .
My reading of tapping head bolt & stud holes is that to gauge the TQ , your need a clean even threads , every industrial eng I've come across also use's a lube , many send out with either the gaskets , bolts/studs , most of it is a molly based , the reasoning behind this is that to get the correct TQ , you do not want the TQ wrench to get any extra reading from dirt/carbon , ruff metal surface , metal shavings , the TQ is not what is put against the threads , but what is put against the shaft of the bolt/stud , also referred to as stretch tension .





t

 

[JHardwick]

also referred to as stretch tension .

High end engine builders no longer check torque on rod bolts etc ..... they measure the stretch with an indicator.



I'b be hesitant to add any grease to the situation. I'd want the bottom of the hole as dry as possible. Adding grease to the tap could hold chips at the bottom of the hole.



As MACHINIST said, copper tubing on an air gun works very well.

 

[MACHINEST]

On the second thought you may not want to use compressed air to blow out the holes under the valve cover,Chips down in the engine not good,How about a vaccum cleaner with rubber gas line on it?

 

[R_Painter]

i put a shop rage over the hole and my hand as I was blowing air into the hole. Changed oil right after stud install and no problems. .

 

[AMassaro]

if you are pulling one head bolt tapping cleaning and installing head studs you only have to do it once I did mine at 125 ftlb and went to the next one. I am running 50 psi of boost and nitrous and factory gasket with just studs. If you cant find a tap you pay for shipping and you can borrow mine.

I spoke with ARP directly about intalling their studs. They recommend 3 torques total to relieve any friction and get the most accurate torque reading. Remove one bolt at a time as mentioned, bottom tap then clean (magnet) the hole. Install stud, use generous ARP lube on top of stud threads, inside the nut and on both sides of the washer, torque to 125ft/lbs. Do the same for all studs, then go back, loosen each one at at time, and torque back down to 125. Then a third and final time and you're done. If you are only doing one torque to 125 you have not removed enough friction from the threads to have the best pull/clamp on the stud and thus on the head.

btw- this is the tap I bought... . Select TAPS - M12X1.75X6" D6 4FL HSS SP PULLEY PLUG TAP

 

[JHardwick]

btw- this is the tap I bought... . Select TAPS - M12X1. 75X6" D6 4FL HSS SP PULLEY PLUG TAP

All good advise, but be aware that a plug tap is not a bottom tap. A plug tap will leave a few tapered threads at the bottom of the hole.



BTW, it seams that un-torqueing and re-torqueing 3 times would dry the thread out making it a "loose" torque?

 

[AMassaro]

When you loosen the nut, you have to re-lube it all over again... not dry. Spoke with Doug (jetpilot) and he confirmed that this is the way to do it BUT he also confirmed that ARP doesn't supply enough lube in that tiny packet to do this correctly. Soooo... I bought a pint of ARP lube from him... I think I have enough to do around 20 sets of studs now... :-laf

 

[ENafziger]

Well, I'm in the middle of installing studs right now, and thought I'd post some pictures for someone thinking about doing this.



#ad


This is with the plastic valve cover box removed.





#ad


Here, the rocker box and the injector gasket/wire assembly have been removed as well.





#ad


View with intake and exhaust rockers removed... ready to start removing one bolt at a time and tapping.





#ad


Rockers laid out in order...







#ad


This is a picture after "bottom-tapping" one of the holes. The additional depth that could be tapped varied slightly, but this is about the average number of holding threads gained by tapping.





I used a M12 x 1. 75 bottoming tap from McMaster Carr for about $12. A 12-point 5/16 socket fit perfectly over the tap, and I welded it to prevent the tap from coming out. It worked very well, as I simply used the right length 1/4" drive extension that would fit in the hole.



I used a magnet in a flexible hose to retrieve metal filings resulting from the tapping process. This may be more beneficial than using compressed air and chancing metal shavings from being blown around. Also, the 6 bolts under the rockers had a significant amount of oil in them... I used a turkey baster type suction bulb to remove the oil.



Have to finish doing the re-torques tonight after work... --Eric

 

[AK RAM]

You know what is really funny?



I talked to ARP not long after they released these studs looking for advice on installing them. At the time, their response was to not bother with a bottom tap…. . take advantage of the Allen key and crank on them as hard as I wanted to run them to the bottom of the hole. Said the stud material is a lot harder than the block and will make new threads as it goes and the little bit of twisting force that this will subject the stud to will not affect it at all. They said to just make sure I lubed the washer and nut well so they do not twist the stud as I torqued them since the stud is not going to turn in the new threads it made (it has a firm grip at that point). 4 years and 6 or 7 retorques later and all is apparently still OK.



Just thought I would share that.

 

[hotram03]

Well I see this is quite the job, oil removal so it does not drain into the bolt holes, I better make sure I ordered a bottoming tap, I thought I did, its the one from MSC. Gee I believe this is now going to be a Sat and Sun project now, especially since its the first time I've ever installed studs on a B motor period. Fun Fun Fun... ... . thanks for all the wisdom guys, my job now takes me out of town for about a month, so when I get into mine I will repost on some of the things you all have told me to try, thanks for the pics they help alot.

 

[jwilliams3]

You know what is really funny?



I talked to ARP not long after they released these studs looking for advice on installing them. At the time, their response was to not bother with a bottom tap…. . take advantage of the Allen key and crank on them as hard as I wanted to run them to the bottom of the hole. Said the stud material is a lot harder than the block and will make new threads as it goes and the little bit of twisting force that this will subject the stud to will not affect it at all. They said to just make sure I lubed the washer and nut well so they do not twist the stud as I torqued them since the stud is not going to turn in the new threads it made (it has a firm grip at that point). 4 years and 6 or 7 retorques later and all is apparently still OK.



Just thought I would share that.

Making new threads with the stud is dangerous... You open yourself up to the potential of spreading the hole boss.

 

[PHeadings]

Just got off the phone with ARP and I was told there is no need to bottom tap with there new 24 valve set of studs. They said they will clear the rocker box issue.

Has anyone held up a stock head bolt to a ARP head stud. The stock head bolt has twice the thread area as the head studs.

 

[jwilliams3]

Ask ARP if they'll buy you a new engine if you rip the threads out of the block:-laf

 

[PHeadings]

Has anyone held up a stock head bolt to a ARP head stud. The stock head bolt has twice the thread area as the head studs.

 

[jwilliams3]

Has anyone held up a stock head bolt to a ARP head stud. The stock head bolt has twice the thread area as the head studs.

Hey Cali dude go outside and measure how thick the head on your engine is.

You'll see that only about an inch of threads on that bolt will engage in your engine block...