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Need input on drilling block for new head studs.
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 09:44AM

I've had to purchase new head studs for my engine and I opted for the oversized from Clark's. Those were purchased several years ago so they can't be returned. The original studs were seized and damaged and several of the hole threads were damaged by a machine shop when removing the old studs. So I'm pretty much locked into these studs.
I'm incredibly nervous about doing this. The new studs are 7/16 x 14 thread requiring me to drill and tap each hole. I have the tools to do it properly. Would this best be done on a drill press? If so, at which speed? Would you use cutting oil?
I know a few of you are probably shaking your heads but this is where I'm at.



Edited 1 time(s). Last edit at 01/11/2020 09:54AM by 63 Spyder Ragtop.

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Re: Need input on drilling block for new head studs.
Posted by: Setterz54 ()
Date: January 11, 2020 10:15AM

Im not a machinist but I would say it would be best to do it on a drill press.You want to make sure you are straight. Also I would use cutting oil.I would also use low speed.Hopefully more people will chime in and correct me if I am wrong.If your still nervous about this maybe its better to take it to a machine shop. Good luck.

Setterz54
Fulton,MD.

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Re: Need input on drilling block for new head studs.
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 10:18AM

Thanks for the reply. I, too, hope more members respond.

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Re: Need input on drilling block for new head studs.
Posted by: roger65180 ()
Date: January 11, 2020 10:22AM

if all else fails just get anouther block . is your spyder a 64 engine. if so any block from 64 and up will work

Roger R
Madison Wi
62 ct pg turbo
65intercooled 180 4sp,autocrosser
62 Rampy

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Re: Need input on drilling block for new head studs.
Posted by: davemotohead ()
Date: January 11, 2020 10:24AM

Most times for a Job like that you use a insert installed in the hole that the stud screws into, I would not thread the aluminum and screw them in, they will pull out when you torque the heads, the originals have a weird Screw thread with interference fit from the factory that were never meant to be replaced, Time Sert actually makes the proper length insert for our engine cases.







1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Need input on drilling block for new head studs.
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 10:26AM

Mines a '63.

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Re: Need input on drilling block for new head studs.
Posted by: Setterz54 ()
Date: January 11, 2020 10:28AM

Glad you said something Dave. I had not thought about a time-cert.

Setterz54
Fulton,MD.

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Re: Need input on drilling block for new head studs.
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 10:29AM

davemotohead Wrote:
-------------------------------------------------------
> Most times for a Job like that you use a insert installed in the hole that the stud screws into, I would not thread the aluminum and screw them in, they will pull out when you torque the heads, the originals have a weird Screw thread with interference fit from the factory that were never meant to be replaced, Time Sert actually makes the proper length insert for our engine cases.

I'm not trying to dis a sponsor but why would Clark's sell these studs?

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Re: Need input on drilling block for new head studs.
Posted by: roger65180 ()
Date: January 11, 2020 10:31AM

if all else fails just get anouther block . is your spyder a 64 engine. if so any block from 64 and up will work does not have to be a turbo block

Roger R
Madison Wi
62 ct pg turbo
65intercooled 180 4sp,autocrosser
62 Rampy

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Re: Need input on drilling block for new head studs.
Posted by: davemotohead ()
Date: January 11, 2020 10:45AM

Later on when Studs started pulling out of engine cases GM did make over size thread replacement studs, I believe they were .001 and .003 over size threads that you heat the hole and thread in place of a pulled stud, Clarks replacement studs are fine and I believe they recommend a time sert as well with their replacement studs install, the insert is the recommended method for replacement studs, I have used them many times with no problem. When building big bore engines or long stroke engines you need to replace the studs with longer ones or stronger ones, I have done entire case's with inserts and the up graded screw in studs.







1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Need input on drilling block for new head studs.
Posted by: jjohnsonjo ()
Date: January 11, 2020 11:06AM

I did one time sert on, my last build. Pretty sure the holes were 90 degrees from the case half and I used my drill press. I also seem to remember have to run a die over the stock stud so it would screw into the sert.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: Need input on drilling block for new head studs.
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 11:15AM

Davemotohead, I am in no way questioning your expertise but trying to understand. You recommended using time certs as you stated that if I tapped the hole and threaded in the new stud that it would pull out when torqued. In order to install a time cert the block would have to be drilled and tapped to accept it. What would keep the time cert from pulling out as opposed to threading the stud into the block? Wouldn't both ways use the entire thread length?
My engine isn't a big bore or long stroke. Please help me understand.

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Re: Need input on drilling block for new head studs.
Posted by: davemotohead ()
Date: January 11, 2020 11:35AM

The time sert insert has the lower portion of the threads smaller than the rest of the insert, When you install them with the installation tool, when it hits bottom the tool expands the lower threads and embeds them into the aluminum locking the insert in place, a interference fit that locks the insert in place, the stud by itself cannot do this, here is a page that explains the process, watch the 6th vid down from the top. [www.timesert.com]







1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Need input on drilling block for new head studs.
Posted by: alphasud ()
Date: January 11, 2020 11:39AM

Time ceros are of a larger diameter and you use a tool that swells the insert slightly to lock it into the hole (at least the last one I used) more surface area equals more strength in the aluminum.

David North Idaho
1965 Corsa Turbo converted to 140
1971 Super Beetle with 2.5L Subaru engine
1965 Corsa mid engine project
1973 Mercedes 280 project

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Re: Need input on drilling block for new head studs.
Posted by: alphasud ()
Date: January 11, 2020 11:46AM

Based on what you are saying about the condition of the head studs, damaged threads I would opt for another engine case unless you have the original case that matches the car and you don’t want to loose that. Even then put out a request on the forum and see if someone has a case with a similar date code.

David North Idaho
1965 Corsa Turbo converted to 140
1971 Super Beetle with 2.5L Subaru engine
1965 Corsa mid engine project
1973 Mercedes 280 project

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Re: Need input on drilling block for new head studs.
Posted by: Spectre ()
Date: January 11, 2020 12:08PM

Time certs the best solution, long helicons work also. In a pinch, I have installed two regular helicons into the hole. I used red locktite on the insert and the stud and never had an issue.

David Clamp


1965 Corsa convertible - 140 4spd/3.55/AM-FM

2013 Mustang GT convertible - 5.0, 6spd auto, Procharger i-1

2003 Miata SE - 6spd manual (wife's toy)

"Victory is mine!" - SG

Norman, OK

<a href="[www.wunderground.com] src="[weathersticker.wunderground.com]; alt="Click for Norman, Oklahoma Forecast" height="90" width="160"></a>

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Re: Need input on drilling block for new head studs.
Posted by: JimBrandberg ()
Date: January 11, 2020 01:50PM

I prefer to weld a nut onto whatever is left of the stud to try and get the old stud to screw out, heating the aluminum might help.
Drilling the studs would be a last resort for me. They are very hard and super easy for a drill to wander off into the aluminum especially when you get to the bigger sizes and almost there.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Need input on drilling block for new head studs.
Posted by: 66vairman ()
Date: January 11, 2020 05:46PM

davemotohead Wrote:
-------------------------------------------------------
> Most times for a Job like that you use a insert installed in the hole that the stud screws into, I would not thread the aluminum and screw them in, they will pull out when you torque the heads, the originals have a weird Screw thread with interference fit from the factory that were never meant to be replaced, Time Sert actually makes the proper length insert for our engine cases.

Correct about the interference thread on the studs. A buddy who is a retired machinist examined a stud that pulled out of a Vair block. The last three to four thread on the stud that screws into the block have the same pitch and crest height, BUT the lower portion of the valley is not as deep, or put another way the inner diameter of the threaded area is greater than the normal thread specifications. This larger diameter is what binds the stud in the block and it's very effective. I got a LM turbo block with a lot of spare parts and someone had removed ALL the studs and in the process BROKE OFF THREE OF THE STUDS nearly flush with the block! BTW breaking a head stud off is not easy.

BTW if you use an TimeSert I highly suggest using a high quality die to cut the the interference threads on stock studs or they tend to jamb in the TimeSert before they screw all the way in. I use Loctite, but ONLY use it after confirming the stud screws into the insert smoothly AND QUICKLY to the desired depth.

Dave - feel free to correct me.

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Re: Need input on drilling block for new head studs.
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 06:05PM

What is the correct length of the time cert for my engine?

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Re: Need input on drilling block for new head studs.
Posted by: JimBrandberg ()
Date: January 12, 2020 06:51AM

I'm sorry I misunderstood that you already have the studs out so my previous post does not apply.
I agree that the stock studs are special. Very hard and tough to reform with a regular grade die.
I usually stay with the stock stud unless I have to change.
Are the aftermarket stock size studs and oversize studs threaded in a special way? Are they super hard like the originals? I don't remember offhand.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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