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-   -   Drill/Tap Specifications for Clutch Mount Boss on Block (https://www.corvetteforum.com/forums/c1-and-c2-corvettes/1606308-drill-tap-specifications-for-clutch-mount-boss-on-block.html)

c66vet 01-24-2007 07:22 AM
Drill/Tap Specifications for Clutch Mount Boss on Block
 
I am planning to install a different engine Block in my car. The clutch mount boss on the block does not have the hole drilled to mount the clutch bellcrank ball stud. Is there anywhere I can get the specifications on depth to tap etc.. I have looked at some other blocks and some of the holes are off center , does this have any effect on the operation of the cluch Z bar? The Block is a Bowtie 10051107, I am assuming that all 66 Corvette Big Block components will mount correctly. Any help is greatly appreciated, Thanks

knight37128 01-24-2007 10:21 AM
If you can find someone to drill and tap the outside of an iron block; let me know who/where.

There is a Z bar conversion piece that bolts up. :thumbs:

http://www.sdpc2000.com/catalog/1006...l-Brackets.htm

67L36Driver 01-24-2007 11:25 AM
Edit:
Refer to post below. Wrong hole, that's one of the oil cooler/plug holes.

I see the correct hole but there is no reference dimensions. You could scale the drawing but that would be a crap shoot.

c66vet 01-24-2007 11:49 AM
Originally Posted by 67L36Driver (Post 1558655125)
A medium to large radial arm drill press should get the job done. Carefull setup is the key to success.

An old Chevy Power catalog I have shows the hole 2.52" forward of the crankcase/bellhousing face and 2.36" above the pan rail. For the thread, just measure the stud. Check the tap drill depth on any SB or BB with a dial caliper.

Keep the drill depth to a min. and use a bottoming tap.:thumbs:
The boss for the corvette clutch bar is located at 11PM above the rear freeze plug. I do not belive these measurments are for that location. This is good information, thanks.

JohnZ 01-24-2007 05:02 PM
The Z-Bar ball stud has a 1/2"-13 thread; on original blocks, the tap drill hole is 0.86" deep, tap depth is 0.70". :thumbs:

c66vet 01-24-2007 09:06 PM
Thank you for the technical detail. I have been on the internet all day trying to find this information. My next step was to call GM.

buns 01-25-2007 01:01 AM
Originally Posted by knight37128 (Post 1558654260)
If you can find someone to drill and tap the outside of an iron block; let me know who/where.
I'm confused by this statement/question. It sounds like you are suggesting that drilling and tapping a cast iron block is difficult.







http://i53.photobucket.com/albums/g6...funny/gif3.gif

knight37128 01-25-2007 10:03 AM
Originally Posted by buns (Post 1558666659)
I'm confused by this statement/question. It sounds like you are suggesting that drilling and tapping a cast iron block is difficult.
Bingo. :yesnod:

New cast iron is not difficult. Old cast iron will crack. Most of the outfits (that I have seen) heat it in an oven before any work is done to cast iron.

JohnZ 01-25-2007 12:17 PM
Originally Posted by c66vet (Post 1558663665)
Thank you for the technical detail. I have been on the internet all day trying to find this information. My next step was to call GM.
They wouldn't have been able to help you anyway - there's nobody left there who even knows what a clutch cross shaft ball stud IS. :)

JohnZ 01-25-2007 12:20 PM
Originally Posted by knight37128 (Post 1558669104)
Bingo. :yesnod:

New cast iron is not difficult. Old cast iron will crack. Most of the outfits (that I have seen) heat it in an oven before any work is done to cast iron.
That's a new one on me - true for weld repairs with nickel rod, but not for machining; never heard of having to oven-heat an iron block before drilling/tapping/machining. :toetap:


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