re-taping head bolts

has anyone changed a block that had 10mm head bolts to 11mm head bolts. Was the threads deep enough to be as strong as a regular 11mm block? How did it work out for you? Thanks

[laserxe84]

Did it on my '84 Laser XE. There's plenty of block material in those holes to tap after you drill out the 10mm threads. I worked for a Chrysler dealer when I did this so I special ordered the MP 11mm tap kit from our parts department for $53. When it came, all it was was a standard 11mm tap and a standard drill bit(I can't remember the size). I was expecting a lot more for $53. The parts guy was nice and didn't make me purchase it. Just went to the local harware store and got a tap and drill bit for around $5! Worked great. No stripping problems(good bolt clamping force) and no headgasket failures. If I were you, I'd get a set of 11mm MP Bolts or ARP Studs, get an 11mm tap that matches those threads, and get the right size drill bit- usually stamped on the tap. To avoid getting metal shavings in the cylinders and water/oil passages, just mask them off with tape, then use a shop vac or compressed air to remove the shavings.

Hope this helps,

Justin Fournier

[ShelbyGLHS592]

I did it to my 1985 block a few years ago. I still have the correct size tap. You can borrow it if you'd like. It would work best if you can put your engine block in a press. I used a press that clamped onto the block.

[QuikTurboZ]

You'll definately want to use some kind of press to keep the drill bit perpendicular to the block surface. This would be very important.

thanks for the info. I will use a mill to do the work, just wanted to make sure the threads would work first.