One Carb Or Two?
Posted 14 April 2025 - 08:31 AM
Hello
Could someone measure the depth of this hole on an 998 A+ block ?
Another three holes are ~16-17 mm, this one is ~11-12 mm, in which I would not tighten a screw
Maybe a broken screw is in it but I am not sure.
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Moved Into The Garage
Posted 14 April 2025 - 09:23 AM
That's a dowel hole - it should have no thread.
Looking at the condition of the cooling jacket - it needs a good acid soaking !
Moved Into The Garage
Posted 14 April 2025 - 09:45 AM
Mmmmm did not the A+ lose the dowels?
One Carb Or Two?
Posted 14 April 2025 - 10:06 AM
Here is my '83 A+ 998
One Carb Or Two?
Posted 14 April 2025 - 10:12 AM
Looking more closely, the location of the dowels on my photo, the dowel should be located on the outer hole (where the finger nail is) so it looks like a broken bolt
One Carb Or Two?
Posted 14 April 2025 - 10:28 AM
That's interesting. I've made a blanking plate - using an old coolant pump for template - to closing the coolant pump opening, I want to fill the block for soaking. All 4 holes are in the correct position for the threaded holes. That shallow is definitely threaded (5/16 UNF)
You can see the "trace" of the dowels but it looks like this block never had them. Maybe it comes from the gasket....
One Carb Or Two?
Posted 14 April 2025 - 04:07 PM
Well it was a screw indeed. I was able to drill it through and broke it pieces. Now I have a pretty clean thread 
I can't imagine how that liitle piece broken from the screw...
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Edited by gaspen, 14 April 2025 - 04:08 PM.
One Carb Or Two?
Moved Into The Garage
Posted Yesterday, 11:14 AM
People just leave them in and they get machined flat with the top face. Then drill a new hole and bash a new scrivit in place.
reusing the hole does not really work as is shape is made when the rivet is hammered home.
Moved Into The Garage
Posted Yesterday, 06:21 PM
They are on the hard side, certainly much harder than the block, HSS drill bits will cut them but they will tend to wander being such a small size. I put the blocks up in the mill and peck at them with a 3 mm carbide end mill, they quickly make mince meat of them, leaving the hole undamaged.
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