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Old 08-26-2014, 02:27 PM   #1
Christoph
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Default How deep are the 14 holes in the block?

14 bolts hold the Head on the engine.

How deep are the 14 holes in the block
(and how deep is the 7/16-14 thread)?

Additional : Did you ever drill any deeper??

Thank you very much

Best regards
Christoph


The head is still on the engine, but i know that a
heli-coil (bolt8, which holds the ignition-cable) did
let go while i retorqued to 55 ft-lbs
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Old 08-26-2014, 03:14 PM   #2
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Default Re: How deep are the 14 holes in the block?

the vendors here offer a special stud that is 1/2" going into the block and the upper portion of the stud is the usual 7/16. I would only do this if i couldnot get another heli-coil in properly. Chances are the helicoil was installed incorrectly; they usually last forever since they are stainless

There is about another 1/4" at the bottom of the stud hole before you hit the water jacket. You could drill this out and tap it but I doubt the extra 1/4 " would do you any good
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Old 08-26-2014, 04:18 PM   #3
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Default Re: How deep are the 14 holes in the block?

who sells that 1/2 stud? I have a block where somebody installed the heli-coil about 3 deg. of vertical.
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Old 08-26-2014, 04:20 PM   #4
BRENT in 10-uh-C
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Default Re: How deep are the 14 holes in the block?

Quote:
Originally Posted by rocket1 View Post
who sells that 1/2 stud? I have a block where somebody installed the heli-coil about 3 deg. of vertical.
http://www.snydersantiqueauto.com/4441
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Old 08-26-2014, 04:53 PM   #5
Christoph
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Default Re: How deep are the 14 holes in the block?

Thank you tbird.
Perfect info !

I need to figure out about things IN ADVANCE.
One Helicoil sadly is "soft"(i cant retorque it) but silicone-head-gasket is stilll ok.

Once i take head out again:
Will try to put in another Helicoil propper.
(only if it still fits PROPPER, i will use some aditional JBweld there).

If this fails (and i guess so) i will drill, screw in a big stud (together with Loctite) , drill that and put in original 7/16-14 again. To do so, i need to know how deep i can drill and how deep i can put in a big thread.

Thank you again.

BTW i will do a long-time-test and leave this silicone gasket alone, as long as it stays ok.
Stud 8 is down to 50% drag . 55ft-lbs would be 75Nm (actually it is at about 45Nm).

Last edited by Christoph; 08-26-2014 at 05:11 PM.
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Old 08-26-2014, 05:06 PM   #6
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Default Re: How deep are the 14 holes in the block?

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rocket:
Once you use a 7/16-14 with helicoil, the outside of this helicoil
is bigger than the outside of an 1/2-13 (special-Stud).
As so you would need to use this 1/2-13 with a helicoil too
They do not sell such helicoils at the vendors ( and it would really be a BIG-diameter).
If this bad-angle-stud still sits good in its heli-coil, i would push a somewhat bigger
drill through the head
Have fun
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Old 08-26-2014, 05:19 PM   #7
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Default Re: How deep are the 14 holes in the block?

slip a pipe over the misaligned stud and bend it verticle.
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Old 08-26-2014, 06:15 PM   #8
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Default Re: How deep are the 14 holes in the block?

Quote:
Originally Posted by Christoph View Post
rocket:
Once you use a 7/16-14 with helicoil, the outside of this helicoil
is bigger than the outside of an 1/2-13 (special-Stud).
As so you would need to use this 1/2-13 with a helicoil too
They do not sell such helicoils at the vendors ( and it would really be a BIG-diameter).
If this bad-angle-stud still sits good in its heli-coil, i would push a somewhat bigger
drill through the head
Have fun
Christoph
The uncompressed OD of a 7/16"-14 helicoil is 0.551. The compressed (target minimum) is 0.526. Thus the threads will "coincide" for a portion and likely interfere (cross thread?) preventing full strength.

There are other thread insert systems you could use. E-Z Loc comes to mind but I see that their 7/16-14 insert requires a 5/8-11 tapped hole - which will work, but may interfere with other cylinder things.

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Old 08-26-2014, 07:05 PM   #9
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Default Re: How deep are the 14 holes in the block?

There are different types of taps. If you use a taper or plug helicoil tap in a bottoming hole and try to cut the threads to the bottom of the hole, the last part of the tap will leave a tapered thread hole for the last 3-4 coil cuts.

Then when you install the helicoil the last 3 coils will have a reduced size.

Then when you install the stud the helicoil will bind up on the stud when you try to install it all the way to the bottom because the last three bottom threads are tapered.

Use a taper tap to start the threads and finish off with a bottoming tap so that the helicoil will not bind up on the last three threads.

Styles Of Taps
The kind of hole to be tapped has much to do with the style of tap that’s best suited. Some holes go all the way through. Others, while not throughholes, still are relatively deep. Some are quite shallow, little deeper than diameter. Each of these three kinds of holes through, deep-bottoming blind, and shallow bottoming, has a tap or group of taps best suited to requirements.
1. Taper Taps have 7 to 10 thread chamfers to distribute cutting action over many teeth and the taper also acts as a guide in starting.

2. Plug Taps, with a chamfer over four threads, is most widely used in through holes and where there is sufficient room at the bottom in blind holes.

3. Bottoming Taps are made with just enough chamfer for starting in the hole, only 1 to 2 half threads. As the name implies, it is designed to thread blind holes to the bottom.




Last edited by Benson; 08-26-2014 at 08:16 PM.
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Old 08-26-2014, 07:41 PM   #10
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Default Re: How deep are the 14 holes in the block?

Quote:
Originally Posted by rocket1 View Post
who sells that 1/2 stud? I have a block where somebody installed the heli-coil about 3 deg. of vertical.
Helicoils are very compliant because they are a wound spring and the threads can move independently. Here's a few crooked ones (not my work!!) in an engine I rebuilt. If you apply some force to the stud with a pipe and deliver a few taps with an 8 oz machinist's hammer to the enlarged diameter base of the stud, they will straighten without bending the stud.

The special helicoil taps leave a lot of 'slop' clearance to thread the spring into, one of the reasons I'm not overly partial to them. I did proof the studs by torquing a sleeve to 65 ft-lbs. Typical of newly installed helicoils, they felt a bit spongy 'till about 50 ft-lbs, then they stop moving against the clearance and feel solid. Proofing the repair with a sleeve and torque wrench saves learning after-the-fact if it will hold.

Either a solid Locknstitch FPS series or Time-sert solid 'bigsert' is a far superior option to correct a hole problem but if there is already a helicoil in place and it is slightly off-vertical I wouldn’t immediately reach for a bigger drill and tap.

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Old 08-27-2014, 12:33 PM   #11
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Default Re: How deep are the 14 holes in the block?

In a "pinch" I've made a "BOTTOMING" tap, by cutting off 1/2 the length of a tapered tap, with a cut off wheel.---BETTER THAN A KICK IN THE HEAD!
Wish I could learn to sharpen DRILL BITS-----------------!
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Old 08-27-2014, 01:16 PM   #12
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Default Re: How deep are the 14 holes in the block?

While I was in the Army in El Paso I worked some weekends welding goose neck trailers for a builder. He showed me how to sharpen drill bits and it sure helped, but I'm still not a pro at it. I'd bet there must be something on the internet showing how it's done. Myabe find something on UTube.
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Old 08-27-2014, 01:42 PM   #13
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Default Re: How deep are the 14 holes in the block?

Bill I didn't cut it off because of a being in a pinch I have cut them off because I was to broke to buy another tap!
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Old 08-27-2014, 02:53 PM   #14
George Miller
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Default Re: How deep are the 14 holes in the block?

Sharping drill bits just takes practice, being a machinist had lots of practice.
You have to keep the point in the center or it will drill over size. Just study a new drill and grind your old one as close as you can to the new one. A fine wheel on your grinder will help.
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Old 08-27-2014, 03:00 PM   #15
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Default Re: How deep are the 14 holes in the block?

Quote:
Originally Posted by Christoph View Post
14 bolts hold the Head on the engine.

How deep are the 14 holes in the block
(and how deep is the 7/16-14 thread)?

Additional : Did you ever drill any deeper??

Thank you very much

Best regards
Christoph


The head is still on the engine, but i know that a
heli-coil (bolt8, which holds the ignition-cable) did
let go while i retorqued to 55 ft-lbs
Not sure how deep the hole is on a Model A head bolt. You could check it with a wire or small drill bit on one of the other holes.
The rule of thumb is 1 and a half the dia of the thread. So about 3/4 of a inch.
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Old 08-27-2014, 03:27 PM   #16
Brentwood Bob
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Default Re: How deep are the 14 holes in the block?

The bottom of the hole is thin and very easy to drill thru. deeper is not good in this case. Bob
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Old 08-27-2014, 03:54 PM   #17
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Default Re: How deep are the 14 holes in the block?

Quote:
Originally Posted by 1930 coupe View Post
I sharpened drill bits by hand for 50 years, and they worked OK. Then my wife got me a Drill Doctor for Christmas and I like it so well that I wish I had one 50 years ago. Get you a Drill Doctor.
I will second that motion!
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