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| bkrantz |
 May 24 2021, 07:37 PM
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#1
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914 Guru  Group: Members Posts: 7,791 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains 
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As I showed in my rebuild thread, I found one of my cylinder heads with an insert for one exhaust stud, but installed at an angle. The other head has one oversize stud hole (9mm?).
My first thoughts: remove the insert and inspect the hole. I may attempt to drill a larger hole at the proper angle and install a bigger insert. If I do that, I may do the same for the other head, which will be the same hole position. Comments? Attached thumbnail(s) 
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| infraredcalvin |
May 24 2021, 09:57 PM
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#2
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Distracted Member Group: Members Posts: 1,523 Joined: 25-August 08 From: Ladera Ranch, CA Member No.: 9,463 Region Association: Southern California
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Look to have plenty of meat, you definitely need straight studs otherwise you won’t get headers/heat exchangers on.
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| JamesM |
May 25 2021, 12:24 AM
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#3
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Senior Member Group: Members Posts: 1,915 Joined: 6-April 06 From: Kearns, UT Member No.: 5,834 Region Association: Intermountain Region |
QUOTE(bkrantz @ May 24 2021, 05:37 PM)  Comments? How much money you looking to spend? Quite a few ways you could go but that all depends on your goals here. The safest bet, get brand new heads, but that obviously isnt an option for everyone. Frugal approach? Assuming you are not looking to have any other work done on the heads, and assuming the insert is the solid style and not a heli-coil, screw a stud and test fit your heat exchangers on the bench. If the stud is still angled well enough to let the heat exchangers slide on properly then I would say that may be the best you could hope for with that head. If you have the proper setup to do so you could attempt to re-drill it straighter and run an oversized insert, but that could be a gamble as well, especially if the current insert is actually functional as is. Personal opinion here, but anything beyond that requiring welding on the head I would just get new (as in brand new) heads. Exhaust stud issues may be my least favorite thing to deal with on 914s |
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| 930cabman |
May 25 2021, 04:36 AM
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#4
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Advanced Member Group: Members Posts: 3,128 Joined: 12-November 20 From: Buffalo Member No.: 24,877 Region Association: North East States
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Agreed with the available meat, but location, location, ..... If you know a friendly machinist I would have him look it over. Given the correct setup, this is simple stuff, given a cordless drill and a bench vise, it's another story
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| stownsen914 |
May 25 2021, 05:57 AM
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#5
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Senior Member Group: Members Posts: 913 Joined: 3-October 06 From: Ossining, NY Member No.: 6,985 Region Association: None |
Ugh, what quality. Should be correctable though. Probably best to have a machinist do it and use a timesert.
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| ClayPerrine |
May 25 2021, 09:37 AM
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#6
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Life's been good to me so far..... Group: Admin Posts: 15,498 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille
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The absolute best way is to have someone remove the insert, and TIG up the hole. Then re-face the surface around the hole, re-drill the hole straight with a 6.8mm drill, and re-tap it. To do it absolutely right requires a vertical milling machine.
Clay |
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| pilothyer |
May 25 2021, 10:10 AM
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#7
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Member Group: Members Posts: 838 Joined: 21-May 08 From: N. Alabama Member No.: 9,080 Region Association: South East States |
QUOTE(ClayPerrine @ May 25 2021, 10:37 AM) The absolute best way is to have someone remove the insert, and TIG up the hole. Then re-face the surface around the hole, re-drill the hole straight with a 6.8mm drill, and re-tap it. To do it absolutely right requires a vertical milling machine. Clay (IMG:style_emoticons/default/agree.gif) This would be the best way to address this problem. |
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| 914_teener |
May 25 2021, 11:31 AM
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#8
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914 Guru Group: Members Posts: 5,201 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
QUOTE(pilothyer @ May 25 2021, 09:10 AM) QUOTE(ClayPerrine @ May 25 2021, 10:37 AM) The absolute best way is to have someone remove the insert, and TIG up the hole. Then re-face the surface around the hole, re-drill the hole straight with a 6.8mm drill, and re-tap it. To do it absolutely right requires a vertical milling machine. Clay (IMG:style_emoticons/default/agree.gif) This would be the best way to address this problem. You are halfway to a new head given this fix. If I were rebuilding a TIV I'd just get new castings and spend the bucks. Just not worth it |
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| Front yard mechanic |
May 25 2021, 06:59 PM
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#9
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Senior Member Group: Members Posts: 1,169 Joined: 23-July 15 From: New Mexico Member No.: 18,984 Region Association: None
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Bolt it up and run it
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| bkrantz |
May 28 2021, 04:08 PM
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#10
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914 Guru Group: Members Posts: 7,791 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains
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I found a machine shop owner that is willing to try removing the insert, welding the hole, and re-drilling for the stud. But he needs an exhaust to be sure the stud position is correct.
Can this be done with the short 75-76 exhaust pipe section? Any difference in exhaust ports or stud locations on the 75-76 heads? |
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| Shivers |
May 28 2021, 04:22 PM
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#11
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Senior Member Group: Members Posts: 2,408 Joined: 19-October 20 From: La Quinta, CA Member No.: 24,781 Region Association: Southern California |
Should be the same
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| DRPHIL914 |
May 28 2021, 04:56 PM
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#12
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Dr. Phil Group: Members Posts: 5,768 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States
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QUOTE(bkrantz @ May 24 2021, 09:37 PM) As I showed in my rebuild thread, I found one of my cylinder heads with an insert for one exhaust stud, but installed at an angle. The other head has one oversize stud hole (9mm?). My first thoughts: remove the insert and inspect the hole. I may attempt to drill a larger hole at the proper angle and install a bigger insert. If I do that, I may do the same for the other head, which will be the same hole position. Comments? @bkrantz is this a new casting?? |
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| JamesM |
May 28 2021, 05:38 PM
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#13
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Senior Member Group: Members Posts: 1,915 Joined: 6-April 06 From: Kearns, UT Member No.: 5,834 Region Association: Intermountain Region |
QUOTE(bkrantz @ May 28 2021, 02:08 PM) I found a machine shop owner that is willing to try removing the insert, welding the hole, and re-drilling for the stud. But he needs an exhaust to be sure the stud position is correct. Can this be done with the short 75-76 exhaust pipe section? Any difference in exhaust ports or stud locations on the 75-76 heads? If this isnt a machine shop that regularly works on type4 heads you might want to rethink that approach. Given the location of that particular stud and its proximity to the combustion chamber and valve seat they may wind up doing more harm than good. |
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| bkrantz |
May 28 2021, 10:06 PM
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#14
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914 Guru Group: Members Posts: 7,791 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains
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QUOTE(DRPHIL914 @ May 28 2021, 04:56 PM) QUOTE(bkrantz @ May 24 2021, 09:37 PM) As I showed in my rebuild thread, I found one of my cylinder heads with an insert for one exhaust stud, but installed at an angle. The other head has one oversize stud hole (9mm?). My first thoughts: remove the insert and inspect the hole. I may attempt to drill a larger hole at the proper angle and install a bigger insert. If I do that, I may do the same for the other head, which will be the same hole position. Comments? @bkrantz is this a new casting?? No, the original head on my 2.0 (I think). But I was dumb and did not recognize the issue before I paid for valve work. |
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| ClayPerrine |
May 28 2021, 10:15 PM
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#15
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Life's been good to me so far..... Group: Admin Posts: 15,498 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille
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QUOTE(bkrantz @ May 28 2021, 05:08 PM) I found a machine shop owner that is willing to try removing the insert, welding the hole, and re-drilling for the stud. But he needs an exhaust to be sure the stud position is correct. Can this be done with the short 75-76 exhaust pipe section? Any difference in exhaust ports or stud locations on the 75-76 heads? When I repair them on the car, I use the short cast section cut off of a 71 914 heat exchanger. I bolt it up with the other stud, and use it as a guide to re-drill the hole. |
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| bkrantz |
May 29 2021, 10:15 PM
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#16
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914 Guru Group: Members Posts: 7,791 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains
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QUOTE(ClayPerrine @ May 28 2021, 10:15 PM) QUOTE(bkrantz @ May 28 2021, 05:08 PM) I found a machine shop owner that is willing to try removing the insert, welding the hole, and re-drilling for the stud. But he needs an exhaust to be sure the stud position is correct. Can this be done with the short 75-76 exhaust pipe section? Any difference in exhaust ports or stud locations on the 75-76 heads? When I repair them on the car, I use the short cast section cut off of a 71 914 heat exchanger. I bolt it up with the other stud, and use it as a guide to re-drill the hole. @ClayPerrine do you have that section handy, and can I rent/borrow it? |
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| ClayPerrine |
May 29 2021, 10:49 PM
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#17
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Life's been good to me so far..... Group: Admin Posts: 15,498 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille
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QUOTE(bkrantz @ May 29 2021, 11:15 PM) QUOTE(ClayPerrine @ May 28 2021, 10:15 PM) QUOTE(bkrantz @ May 28 2021, 05:08 PM) I found a machine shop owner that is willing to try removing the insert, welding the hole, and re-drilling for the stud. But he needs an exhaust to be sure the stud position is correct. Can this be done with the short 75-76 exhaust pipe section? Any difference in exhaust ports or stud locations on the 75-76 heads? When I repair them on the car, I use the short cast section cut off of a 71 914 heat exchanger. I bolt it up with the other stud, and use it as a guide to re-drill the hole. @ClayPerrine do you have that section handy, and can I rent/borrow it? Yes. It is in my tool box. PM me your address and I will send it. Clay |
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| 914werke |
May 30 2021, 09:08 AM
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#18
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"I got blisters on me fingers" Group: Members Posts: 10,116 Joined: 22-March 03 From: USofA Member No.: 453 Region Association: Pacific Northwest
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QUOTE(ClayPerrine @ May 28 2021, 09:15 PM) I use the short cast section cut off of a 71 914 heat exchanger. I bolt it up with the other stud, and use it as a guide to re-drill the hole. (IMG:style_emoticons/default/smile.gif) Keen minds think alike. I did the same but I also drilled it up to accept an actual hardened drill guide. Then got 2-3 guides of varing ID size so I could driil-out the broken stud & preserve the head whenever possible. |
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| bkrantz |
May 30 2021, 08:33 PM
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#19
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914 Guru Group: Members Posts: 7,791 Joined: 3-August 19 From: SW Colorado Member No.: 23,343 Region Association: Rocky Mountains
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QUOTE(ClayPerrine @ May 29 2021, 10:49 PM) QUOTE(bkrantz @ May 29 2021, 11:15 PM) QUOTE(ClayPerrine @ May 28 2021, 10:15 PM) QUOTE(bkrantz @ May 28 2021, 05:08 PM) I found a machine shop owner that is willing to try removing the insert, welding the hole, and re-drilling for the stud. But he needs an exhaust to be sure the stud position is correct. Can this be done with the short 75-76 exhaust pipe section? Any difference in exhaust ports or stud locations on the 75-76 heads? When I repair them on the car, I use the short cast section cut off of a 71 914 heat exchanger. I bolt it up with the other stud, and use it as a guide to re-drill the hole. @ClayPerrine do you have that section handy, and can I rent/borrow it? Yes. It is in my tool box. PM me your address and I will send it. Clay Thanks. PM sent. |
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