how to fix a stripped thread under locator dowel

[stimpy]

I have recieved a BBc that when we tried to remove a head the bolt wouldn't come out of the hole , it was turning but not backing out , upon removing the water pump what do I find ?? a nut ! apparently some Bozo stripped ou the threads in the block and used a longer bolt and nut to hold the head on , now I want to repair this stripped outhole but don't want to screw up the locating dowel location will a Helicoil work in this situation ?? and NO I don't want to have to buy another block .

[Geezer2]

Heli-coil it!

[brianrupnow]

Stimpy---To save the locating dowel position, and save the block without taking it to a machine shop, you may have to make a drill jig out of 3/4" or 1" plate, with a shape and bolt pattern that exactly matches the waterpump housing. Use a set of transfer punches to exactly duplicate the positions of the water pump bolts and the dowel pin, but don't drill the holes oversize---drill them about .005 thou. greater than the actual water pump bolts and dowel.---On the position that has the broken stud, drill that hole the same diameter as the tap drill for whatever sized bolt you are removing. Bolt the plate onto the block, and use it as a guide to drill out the broken bolt. That way, your drill will not "wander" and the position will be dead nuts. If the threads are totally stripped out, you can use the same method to accurately position a helicoil----Or---drill and tap one size larger and use a "stepped" stud, on which the threads on one end screw into the block, while the smaller threads on the other end match your waterpump bolts.

[R Pope]

The helicoil kit comes with a drill bit to clean out the old threads. This bit should be a tight fit in the hole in the head. I have used a spare head as a guide when drilling the pilot hole, so the bit doesn't wander. Fixed a few engines that way.
Never heard of anybody putting a nut inside the block before! Of course, most head bolts aren't accessible from the water pump holes. Somebody was thinking cheap!

[pat mccarthy]

the drill for the helicoil should center up good to do the job just fine i wish i could tell you i never put any in a bbc but i have the older block and the more times the heads have been on and off so many times .it seams to only happen just when your tq the heads up for the last time i use a 2-3 block to hold the drill square and step drill up to the size of drill but if the threads are gone then it is just about to tap size i used the block is a sight down the side of the drill bit and i ues the 2-3 block to start the tap to .i had a 427 i put in 4 in one side of the deck you do not need to put it up on a mill if you take some time the hollow dowel will work it will just dead head up to the new threads

[stimpy]

very funny denny , I left my x-ray glasses at someones house ... Pat so what your saying is the helicoil isn't larger than the hole of the dowel O.D.? well I guess I shall drill and fi this one out , its a 74 2bolt block out of a burb nothing special . just might use it for a mild upbuild .

[stimpy]

sorry it took so long denny I have been on the road this last week ,I will try to get a picture of it this weekend

[pat mccarthy]

very funny denny , I left my x-ray glasses at someones house ... Pat so what your saying is the helicoil isn't larger than the hole of the dowel O.D.? well I guess I shall drill and fi this one out , its a 74 2bolt block out of a burb nothing special . just might use it for a mild upbuild .

yes it will be just fine