try using an allen bolt they tend to come in all types of heads from socket to oval.

 

Monday - chased down 7/16 bolts, got Fastenal to break packages (did not need 25 of each); only other bolt store near me has $50 minimum. Bought 7/16-14 tap. Spec was drill bit size "U", purchased that as well.

Here's a question though - should tap drill size be different in aluminium vs steel (the old 75% vs 50% thread question)?

Removed the one helicoil I had installed. Threads in the hole were stripped out where helicoil was, I wonder if the bit size for it was too large for aluminum?

Tuesday - cleaned up intake again, must have used a little too much RTV, spread very thin is the next plan.

The slot under the water hose connector (no hole) won't pass the 7/16. Will just have to get out my Armstrong Milling Machine (flat bastard file).

Holes in valley pan gasket clear a 7/16, but barely, so alignment would be even more of a problem. Enlarge? Comments from attending partz vulturez on higher branches of the shade tree are encouraged.

 

Buzz, a few things.
McMaster Carr. Almost always cheaper than Fastenal and I get me stuff in 1-2 days max.
What are you using the fix a threads for? I thought you were drilling and tapping for 7/16" bolt, period?
I've never used RTV around that coolant passage and I don't think the RAVE calls for it. And none of my valley pan jobs have leaked there. Only goop up the RTV in the corners of the end gaskets.

 

Availability vs shipping delays, gotta get this thing done. Yes, I have a McMaster Carr catalog that is thicker than a phone book.

On first try, I had just one that stripped out, so tried the generic helicoil route. I suspect that their stated drill size is for steel, and it stripped out. On second try I had more regular holes strip out and then I "discovered" that torque in RAVE for a D2 and some Rangies is 51 nm and D1 is 38 nm.

Since gaskets didn't line up, I though about using the method on Cannibal's web site
Valley Pan Gasket & End Seals - just used too much. Agree should not need it per RAVE, other than corners, but with alignment I was trying to cover other possibilities.

So now I am set to start tapping, but want to be sure I have right sized bit for aluminum. Like in this reference. Tap Drill Chart

Also wondering what impact larger bolts will have on valley gasket alignment - the existing gasket holes are just a clear drill for the 7/16.

 

from dweb:

"When you put the heads back on, there is sufficient movement on the head dowels to enable the heads to be tightened down out of alignment with the inlet manifold.

When we do ours, we assemble the inlet manifold to the heads using the old gasket and one bolt at each corner, just nipped up.

Then we tighten the heads down, knowing that they are matched to the inlet manifold. Subsequently you can fit the manifold with a new gasket. " - listerdiesel

 

At this point, with new head bolts torqued down, I'd be looking at new bolts for heads I guess, although some will say measure them and re-use as they have not gone thru any heat cycles. Since I now have to drill and tap new holes for intake bolts, enlarging those in the gasket can also be done. Perhaps avoiding second set of new head bolts and re-do of that.

I must confess that I don't spend a lot of time on Dweb, and until this point had utmost faith in the RAVE. Rover's Are Very Exasperating.....

One thing about the RTV, it left a trail that showed gasket was lined up better than I thought.

 

Here's what I found on tapping aluminum.
tapping aluminum, help! - GT40s.com
There's mention of special tapping fluid and even special aluminum taps, but nothing about different sizes.
Here's another interesting read suggesting thread forming taps vs thread cutting taps.
The Home Machinist! • View topic - Tapping aluminum.

The one reccuring tip is to go slow, use lubricant, back off the tap to clean the threads, and pull the tap out to clean out the shavings.
I've drilled and tapped the bottoms of 4-5 diffs to go from 3/8-20 BSF to 7/16-16 for mounting diff gaurds. I've had no problems at all and I just used PB Blaster as Lube and went slow.

I think the two most crucial things are that you have a quality drill bit and a quality tap.

 

Buzz,The way it is shown on your link is how I did mine with the ultra black rtv and let sit for a few days to be sure it is cured

 

The RAVE method has never failed me. And seeing all that RTV cakes inside the intake should tell you something.

 

The "U" drill bit is correct for aluminum. And yes, use lots of oil, back the tap out frequently to clear the cuttings and take your time. Aluminum will chip during tapping if you try to force it. Plus, without a through-hole you end up with lots of cuttings piled up in the bottom of the hole if you aren't careful.

Good luck. I feel your pain.