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Discussion Starter · #1 ·
Hoping someone here can point me in the right direction. I have the boss modular iron block and had the passenger side timing chain arm pivot dowel break off in the block.

Looking for advice on the best way to remove the press in dowel as id rather not mess the block up. I've looked into this issue myself and most the problems I've seen are with the aluminum thread in dowels not the iron press in.

Not exactly sure why it broke as it has been in there for 6+ years but if anyone thinks I'm under thinking this and just replacing it and the damage it caused and moving on feel free to let me know.

Picture is included. Thanks.
175608
 

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The best way to remove and replace the damaged dowel is to have it EDM'd out. If you are not familiar, EDM stands for electrical discharge machining. The service provider will be to easily remove the dowel. This service approach will require removing the block from the car, disassembling the engine and taking the empty block to the EDM shop.

Th alternatives to the EDM approach all involve some sort of drilling and tapping which is at best difficult to do accurately and more often than not results in a damaged block.

Once the dowel is removed I would suggest replacing it with an industry standard metric dowel pin from a place like McMaster-Carr. Some of the dowels Ford uses are relatively soft with a low tensile strength although this is not one that I would anticipate being weak however, when all is said and done yours is broken,

Dowel pin breaking strength is rated in pounds for the pin in double shear. An 8mm dowel pin made from 52100 alloy steel will carry a double shear breaking strength rating of 11,800 lbs. The McMaster website listing does not indicate the single shear rating, which would be lower. I would encourage you to use the strongest pin you can find.

You have-not indicated how the engine is operated. If you are using a two step for launching you might want to consider a more rigorous maintenance schedule for cam drive components. The staccato on/off, on/off engine operation delivered by two steps to maintain launch rpm is demanding on cam drive components, including the pivot dowels. On the other hand you may have been the victim of just bad luck however, if you do use a two step you might want to consider upgrading your maintenance regimen for the cam drive components including chains, pivots and chain sprockets.


Ed
 

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I broke an 8mm pin in my teksid block and had to use a dremel with a tungsten bit to grind it. I then helicoiled it. It wasn't super fun, but we got 'er done. Block is still in service today.
 

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Discussion Starter · #4 ·
Thanks for your input Ed. Truly appreciate it.

Its a turbo 4v car with a manual transmission that is not set up for drag racing. More or less road race so no two step, hard launching, etc.

With that being said tho I've rebuilt it a few times over the years as I've been changing things or noticing potential issues and have replaced the timing components (chains, tensioners, sprockets, followers, all the guides have been replaced each time, etc).

I have normally would not have an issue and would have already taken it to a shop to remove however, all are booked up with race season, are a crap shop I'd never go to, or have no interest in doing it as their profit isn't worth the time for them to do it. Which that one is a direct quote so I'm kind of annoyed at that shop as I've went there for years and likely will never go back now as they do good work but no longer care about customers apparently.
 

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Discussion Starter · #5 ·
I broke an 8mm pin in my teksid block and had to use a dremel with a tungsten bit to grind it. I then helicoiled it. It wasn't super fun, but we got 'er done. Block is still in service today.
Oh I wish this block was thread in dowels as I'd just do the same and upgrade to the stronger thread in dowels while I was at it.
 

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Thanks for your input Ed. Truly appreciate it.

Its a turbo 4v car with a manual transmission that is not set up for drag racing. More or less road race so no two step, hard launching, etc.

With that being said tho I've rebuilt it a few times over the years as I've been changing things or noticing potential issues and have replaced the timing components (chains, tensioners, sprockets, followers, all the guides have been replaced each time, etc).

I have normally would not have an issue and would have already taken it to a shop to remove however, all are booked up with race season, are a crap shop I'd never go to, or have no interest in doing it as their profit isn't worth the time for them to do it. Which that one is a direct quote so I'm kind of annoyed at that shop as I've went there for years and likely will never go back now as they do good work but no longer care about customers apparently.

You just drew a bad hand on this particular round 98_svt. We all get one of those from time to time. Check out the EDM shops in your local area. They do a really nice job of removing these sorts of things. Last time I had one extracted the price was right around $100. I think the price you experience will be related to geographic location and the number of competitive alternatives available.

When you see the job they do you will be impressed. They leave no marks just an empty dowel pin hole waiting for the replacement pin.


Ed
 

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Discussion Starter · #7 ·
So I called around a bunch today and didn't have luck.

So I tried my hand at a drill and tap removal and had great success. Pulled it straight out after threading a small bolt through it.


Which brings me to my next observation. There is the remains of a very thin sleeve that appears to be placed inside the dowel hole that i can only imagine was put in after casting to fix a mistake at the factory. Is this a common practice?

****note I bought the block new from Ford and the broken dowel I removed was the original one that was installed after purchase.
 

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Measure the ID of the hole. If it is the same as the good dowel then it was a factory repair. If not then it has to come out so a properly sized dowel pin can go in.


Ed


p.s. congrats on the good luck removing the broken pin. Usually they are hardened making drilling not an option.
 

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Discussion Starter · #9 ·
I wasn't even going to attempt to do the drilling until i dug the broken dowel out of the oil pan. After no good news calling different shops focusing on an edm removal i did some sample drilling into the broken off dowel and decided it was something I could easily drill..

ID of the sleeve/bushing is the correct size for the dowel but its partially shattered. Going to attempt to remove the rest of it today. It looks like I'll either be using around a 9/10mm dowel after its out but will get a final measurement of that and if needed adjust to a proper dowel size.
Thanks again for your help.
 

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Glad to hear the removal went as well as it did. The repair is waiting, lets hope it is a replay of the removal effort. 👍

Ed
 
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