What kind of a chore is it to enlarge the bolt holes in the block from 10 to 11mm and how does one go about it without screwing things up?
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What kind of a chore is it to enlarge the bolt holes in the block from 10 to 11mm and how does one go about it without screwing things up?
When I do it in car, I bolt on my deck plate to use as a guide for the drill bit. If you don't have a deck plate, you probably should make up a jig so you drill those holes perfectly straight. You have to make sure your drilling straight. The good news is they are both 1.5 pitch. After drilling, the leftover threads from the 10mm , will help you guide the 11mm tap.
Buy a good quality HSS "bottoming" tap and it will last you a long time. Buy a Chinese POS tap and it will probably be dull by the time your done. Use plenty of cutting oil and back out tap frequently when tapping. If you haven't done this before, I would suggest viewing some U-tube videos before starting on your block.
Also if this is a 85 block & using a 85 g-head, you will need to drill out the head as well. This sounds more difficult than it actually is. The head can be done in like 10 minutes.
Todd
if it's going to stay unmodified it might be easier to just go O-C-D on the head gasket installation
but IF you want to "do something" with it then yeah do the threads
Something like this might help keep the drill aligned.
https://smile.amazon.com/BIG-GATOR-T...-no-redirect=1
Exactly, If you can't or don't want to make your own jig, this would work. I made similar ones for drilling and tapping for 4 bolt main caps.Quote:
Originally Posted by cordes