Helicoiling the head bolt holes in the block

[Mc Tool]

As above , I have acquired a good block that someone has stripped a couple of the threads in the block (fitted arp studs lubed everything with assembly grease and torqued to standard specs ) so Im going to have a go . Anyone got any brilliant ideas how to make sure the holes are drilled and threaded square to the head gasket surface ? I do have a pair of early small valve heads I am prepared to sacrifice so I could use them as a guide if that would do ....somehow .

[SuperV8]

Can you clamp a drill press to your deck?

[stevieturbo]

you can get various tools to assist with drilling square, but patience is a good one.

Is the engine in the car or out ? ie, do you have good access to make it easier to drill ?

You could have a steel plate/guide made up to affix to the head over any hole to try and ensure the drill bit and then tap doesn't deviate. Although you'd need multiple sizes for various threads.

When I tapped my head studs out to 1/2" on my LS, I made a large guide plate to bolt to the head with say 20mm holes in it, than had different snug inserts/sleeves made up to fit into these holes to suit the drill bit and then tap bit to ensure they were straight.

But for one or two small holes, even just having someone eyeball your drill bit as you go should suffice. Once the drill is straight, it should be easier to ensure the tap is then straight too.

[Mc Tool]

Motor is on engine stand , and I do have a big drill press but I cant really see a way to use that .
I sorta figured that the unc end of the stud will fit thru the bolt hole in the head ....and thusly so will a drill bit the right size to drill out the threads in the block ( might have to buy a longer drill bit ....200mm ). I havnt bought the re-thread kit yet but I figure that with the head located on them wee dowels I can drill the block to remove threads and then drill ¾ way thru the bolt holes in the head so as to align the re-thread tap and then tap out the head and on thru to the block . Im thinking that as long as I can start the tap square I should be able to then remove the head and finish the tapping of the block .
Ha ! even as Im typing this I thinking that this might not be the drama I was not looking forward to after all .
Just that I recall many years ago ( like 40 ish ) in a shed ,way past midnight and well into our 2nd crate of beers having re-studded a old Suzuki trail bike cylinder and giving the studs a good whack with a hammer to "align" the (8mm) studs so we could get the head on .
Those were the days ??

[SuperV8]

I also had a stud pull out when torquing my ARP stud nuts down - so I did a helicoil by hand, using a second set of eyeballs and a couple engineers squares and it worked fine, though neaveracking! Used a two helicoils so I had enough thread engagement.

This is what I was thinking for a cheap drill press - could clamp the base to your block, and cut out a large hole in the base so you can see/line up your hole :

[stevieturbo]

Head studs are a bit trickier and less room for error.

I did my RV8 manually years ago, thinking I was great, until I screwed the studs in and they were all crooked and the head wouldn't fit on !!

A big hammer did resolve this...and when it came apart some time later the head came off fine LOL.

But here is a better example of doing it DIY right, which is basically what I did although the fixture I made was only 4 holes so you could only do a couple at a time then it needed moved.

[Mc Tool]

I also had a stud pull out when torquing my ARP stud nuts down - so I did a helicoil by hand, using a second set of eyeballs and a couple engineers squares and it worked fine, though neaveracking! Used a two helicoils so I had enough thread engagement.

This is what I was thinking for a cheap drill press - could clamp the base to your block, and cut out a large hole in the base so you can see/line up your hole :

Ya know I not long gave away a small drill press that would have done that job .....maybe , I dont think the chuck would have been big enough.
I was thinking that I would use 2 helicoils too.
Now the question is ....do I do all the holes or just the stripped ones ......thinking that the p o had torqued all the studs and anything not actually stripped was likely to be close to stripped . Im inclined to do the 20 main holes as the p o did state that the other 8 ( along the outer edge of the heads ) he only torqued to 40 f/lb's

[SuperV8]

Now the question is ....do I do all the holes or just the stripped ones ......thinking that the p o had torqued all the studs and anything not actually stripped was likely to be close to stripped . Im inclined to do the 20 main holes as the p o did state that the other 8 ( along the outer edge of the heads ) he only torqued to 40 f/lb's

Ah the eternal question!
Do you feel lucky punk!
For me, all my stud nuts felt good - except one, which got nowhere near the torque - I kept going thinking this is strange and hopefully will get tight soon! waiting for my brain to click in and realise 'Houston we have a problem'!
If I had chosen to do all the threads - I don't think i'd have done them all by hand without some sort of jig/drill press.

[stevieturbo]

I also had a stud pull out when torquing my ARP stud nuts down - so I did a helicoil by hand, using a second set of eyeballs and a couple engineers squares and it worked fine, though neaveracking! Used a two helicoils so I had enough thread engagement.

This is what I was thinking for a cheap drill press - could clamp the base to your block, and cut out a large hole in the base so you can see/line up your hole :

Easier said than done.

Pretty sure when I did my RV8 block I tried to use this first, but it was just poop.

https://media.zinio.ahpc.us/images/wood ... 311467.png

The plate and guide method as per the Tick video and I did with my LS, is just more foolproof.

I had a first guide made up to locate on the OE bolt or stud. Then I'd clamp the guide block down. This then allowed the new drill bit guide, and then tap guide to be used to complete the task
It's slow, but worked very well.

Tick went one step further and made a guide plate to do all 10 studs at the same time. For me that wasn't as easy to make a plate with such accuracy.