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Old Opeler
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5,564 Posts
Discussion Starter · #1 ·
Opel, in their wisdom, used 9mm X 1.25 pitch , non-standard, bolts to attach the exhaust/intake manifolds to the head. If the PO throws away these bolts when stripping a motor - or you lose them - the you are doomed to wander Opeldom trying to find someone who has spares ....

That, coupled with the fact the original hex bolts are very difficult to reach and do up with Irmscher DSD intake manifolds and a later style swept back exhaust, has lead me to make a set of "special" non-standard bolts by turning down the shank of some 10mm stainless, allen-head, cap screws.

I will be able to use a ball-ended allen key to run them intothe head now.
 

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Old Opeler
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5,564 Posts
Discussion Starter · #3 ·
Lots!

RK,
The original 10mm, marine grade, capscrews are $4.50 each and I spent an hour last night, after my 'real' job, turning them to size and threading the first one (five more to go tonight!). So $27 cost price for 10mm cap screws and an hour of labour - plus postage from NZ to there would not leave much change from $100!
Besides which I am not into commercial production as the time would have to come out of my own Opel fixin' time! LOTS more stuff for me to do for myself yet - sorry.

Just loadd up the pic to show what can be done so if there is anyone over there that can do them for you ........
 

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Another option, just sitting here looking at this post, without knowing the possibility, is to put in some ARP 12 point, 10 mm head, exhaust bolts that are 8 X 1.25 stainless. The ones I'm using on my V-6 are 1 inch long, about, come in 5 bolt bubble packs with stainless washers, or you can get them in grade 8 steel too. Also the heli-coil 8 X 1.25 kit is available from NAPA with a bunch of inserts, tap and installation tool. Just a suggestion.
 

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I almost spit my coffee on the computer screen when I saw this post. I would have eaten a roach for a couple the other day. When installing the new engine in the GT week before last, I noticed there were a couple bolts in the exhaust manifold that weren't the same and didn't fit correctly. We checked the size of the bolts(the correct ones)...9mm. Everyone at the dealership was like, "You're kidding, right? If not, you're SOL! Better start looking overseas." So I did the next best thing and called OGTS. Even NOS is a bit expensive, BTW.
 

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Kick a little asphalt
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1,485 Posts
Another option is to modify the original bolts. I milled the heads to fit a 13mm socket rather than the 15mm that is needed originally. It's a simple process on a milling machine or you could have any local machine shop do it for you for about 20 bucks. It allows much more room to get on the bolt and turn it without being up against the manifolds.

Duane
 

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Certified Opelholic
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1,539 Posts
Did you guys know that Rally Bob used to sell 9 mm stainless Allen-head, cap screws.

One of these times I will scan one of his price sheets of all the stuff that was offered at one time.

you should see the stuff in the Manta-Part catalog also


Davegt27
 

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PrOpeller
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707 Posts
OGTS sells 9mm allen-head bolts (GM parts). These might not be listed in their catalog.

I still had to make a crazy looking wrench out of a bicycle hex brake tool in order to reach the bolts on my short sidedraft manifolds...would like to find a better solution that requires even less clearance. :eek:
 

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The neat thing about the twelve point bolts is that first, you don't have to turn it very far (thirty degrees) before you can lift the wrench and get another bite. Allen heads are still six points, so you have to go twice as far before getting another bite. The next good point is that the twelve point bolt head is much smaller than normal, you'll be using a very small wrench in that nasty little tight spot.
I use them whenever and wherever possible. As for my GT, countless bolt holes have been helicoiled to 1/4, 5/16 and 3/8. Race cars have to be easy to work on, when you booby trap them to be difficult they become no fun.
Before every race somebody has to check every single nut and bolt on the car. Make it simple. When there is a problem there is no time to be fighting a booby trap. Make it easy.
Try them on the middle holes of a small block chevy intake manifold. And the headers on anything. You'll like it.
Besides, metric threads just suck. They just seem to sieze or gall or strip so much easier than standard. When taking apart big trucks I prefer to impact them tighter to twist them off, it's quicker and easier than trying to remove them properly. Unless they go into a blind hole, naturally...
 

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Opeler
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399 Posts
manifold screws

Hi everybody,
Just finished taking the manifolds out and this is what i got..
One screw broke in the block and six others broke in the exhaust manifold (where the exhaust pipe is installed).Any ideas on how to take the screw out of the block,it is all rusted.The six in the exhaust manifold I drilled out but I need to re-thread.What size do you recommend.Would like to go to US not metric.
Any help,direction and such would be greatly appreciated
 

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why are you saying that these bolts are hard to find? when i attached the manifolds to my engine for my gt when the engine was put it, it was done at my school's mechanics shop, i just found a random box of bolts, which was a new box, probably bought less than a month before, and they fit perfect... it was a metric size, i don't remember the size though

:confused:
 

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'72 Opel GT (Sara)
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2,119 Posts
I've had one of my manifold bolts wiggle lose and disappear. Is there a known source for these such as a national auto parts chain or one of the on-line hardware sites? While it would be a great excuse to buy something else :), it seems silly to have one bolt shipped from OGTS. If you know of a source, please link it here and then it will be available for future reference.

Thanks,

Matt
 

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Super Moderator
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I've had one of my manifold bolts wiggle lose and disappear. Is there a known source for these such as a national auto parts chain or one of the on-line hardware sites? While it would be a great excuse to buy something else :), it seems silly to have one bolt shipped from OGTS. If you know of a source, please link it here and then it will be available for future reference.

Thanks,

Matt
Matt;
Most fastener houses may have a good laugh at your expense. You'd be better off just getting one from another member.
 

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'72 Opel GT (Sara)
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2,119 Posts
Matt;
Most fastener houses may have a good laugh at your expense. You'd be better off just getting one from another member.
Yeah - I was hoping someone might know that Pep Boys (for example) happens to stock these for some other car or something like that - something I can get local.
 
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...it seems silly to have one bolt shipped from OGTS.
I found OGTS very good helping me when I am missing single bolt or other small item. They will put it in the envelope and mail it to me. The cost of mailing is negligible.
This is how I got from them one bolt for transmission to block connection (the thread was stripped), one 27 mm driveshaft nut (MIA) and the other day, plastic 90 degrees knee between brake fluid tank and the master cylinder.
We are lucky to have OGTS.:yup:
 
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