Trouble torquing the head studs

[Unregistered]

I am coming back to you for yet another question on my A-4. I recently had to take off the head to free up two stuck valve. When I put back the head I could not torque two of the studs back to 35lb-ft. The positions of these two studs are the corner two on the port side (sorry I left my Moyer manual on the boat and cannot remember the numbers). I read your instruction in one of the guest logs on how to repair failed stud. My question is (1) if I can use your new 7/16 stud repair package to fix them or I need to take the head off again to fix them with 1/2" bushing, or (2) I can use JB Weld to simply "weld" the existing 3/8 stud in the block (a bit of wishful thinking on my part). I have not taken the A-4 off my boat and the access from the top is very poor. So, if I need to drill the hole with 7/16 drill the access can be a significant challenge.

[Don Moyer]

The 7/16" repair studs should work well in your application. JB Weld will seldom hold once the studs have pulled free as yours have obviously done.

The big advantage of these repair studs is that they can be installed through the head without removing the head, but it's best to run a 7/16" drill through the hole in the head before using the tap. This is not difficult since the holes are just several thousands under 7/16" originally. In cases of very limited access, it's usually possible to work a 7/16" drill bit down through the head by turning it with a vise grip or small pipe wrench. You should put tape or a drill stop on the drill so that you don't drill into the block. Enlarging the holes in the head to 7/16" gives you a better feel for using the 7/16" taps in the block and seating the studs.

You can check out the studs (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=OBLK_06_42) in our online catalog at moyermarine.com. We also have recently introduced a kit (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=KTAS_04_446) designed to make it easy to install the studs. I'm attaching a set of the instructions that comes with the kits.

Regards,

Don

[gilbert landin]

Don, I have read the PDF for installing the repair stud on the engine head. I cant tell how much thread is in the block or if there is any of the old stud left in the hole, how deep should the stud hole be? Or how deep should I drill into the block thru the head?

[Don Moyer]

Gilbert,

Each of the stud holes on top of the block enter into the water jacket, except for one; this is the center hole in the rear of the block, just ahead of the coil bracket. This means that you can safely drill into the water jacket in any of the other stud holes, and because the one ahead of the coil bracket doesn't enter the water jacket, we've never seen that hole to need any remediation effort.

In the unlikely event that you would twist off the stud in the hole that doesn't enter the water jacket, you can safely drill to a depth of 3/4", and even then, you would only encounter the bolt hole for the coil bracket, which usually doesn't create a problem.

All that being said, you will encounter the contour of the water jacket off to the side of most holes if you continue to run a tapered threading tap straight down to the required depth below most holes. This is the reason we include a blunt "bottoming" tap in our installation kits. After getting a good start with the tapered tap, you can switch to the bottoming tap to thread the hole deep enough to accommodate the coarse threads on the bottom of the repair stud.

In some cases, a very hard calcified deposit of crud will build up in the stud hole, just ahead of the stud, which can give the impression that a piece of the stud has broken off and is still in the hole. You can quickly resolve that issue by taking an ice pick or small screwdriver and tapping your way through the hole and into the water jacket.

Don

[gilbert landin]

I dont know what I was thinking I guess I wanted to cover all the bases before my kit arrived. You are right when i pulled the stud out cooling water gushed out. I have a fresh water cooling system under pressure. How do you tighten the stud w/o taking off the head?

[Don Moyer]

Gilbert,

All 7/16" repair studs come with extra length on top of the stud, so you can usually seat the stud all the way to the top of the lower threaded section by "double nutting" the top of the stud. Double nutting is done by tightening two nuts against each other on top of the stud, and then using an open ended wrench on the top nut to turn the stud into the block. After the job is finished you can either cut the excess stud off with a hack saw, or leave it on.

Don

[gilbert landin]

I knew that.. as usall you guys think of everything to make our job easier.