After re-arranging the valley pan gasket slightly, cleaning out all bolt holes for it with a band new tap, drilling and installing the helicoil (generic) in one bolt hole; I was ready to put intake back. I sealed the lip seals, the corners, and around the 4 water channels per Cannibal's web page. Made sense to me, as the valley pan didn't want to line up.

Last time I did this I got to 51 nm on every bolt except one, which I heli coiled today.

Today I got to 51 nm on one bolt of 12. At least 8, perhaps 10, would only go to 40 nm (approx) before loss of tension (stripped out). This included the heli-coiled bolt.

I attribute this to my own stupidity; cleaning out bolt holes with a tap, and perhaps an old tension torque wrench that is not as accurate as it needed to be.

Path "A" would be to leave as is and see what happens when finished. RTV is around coolant passages at front. There is no oil pressure to deal with in the intake manifold, and the air passages are a vacuum, not pressure.

Path "B" would be to remove intake, and purchase another brand of Helicoil for all bolt holes with longer inserts. And a new torque wrench.

Path "C" would be to drill out each of the 12 holes to a new diameter and tap and use brand new bolts of a slightly larger size. Bolt holes are not drilled 90 degree to face, seems "tilted" a bit.

Path "D" would be to use one of the epoxy products, that fills the hole, but I believe most of those are not rated for 51 nm.

Path "E" involves a match and five gallons of .....

What do ya'll think?

 

Buzz, I have never been blessed with a stripped bolt on one of our engines hence I am not one for helping you, but when all else fails, yes, 5 gallons of gas and a bottle of whisky may be required.
Let us know what you try and the results.

 

Some of this old school liquid should help. I'm going for new 7/16 bolts. Problem is helicoiled hole was drilled out to 25/64th, which same drill size for a 7/16 tap.... There appears to be enough meat to drill into, and the bolt holes on the intake could handle a 1/2.

 

I think a new torque wrench is in order. Or at least calibrate yours.
How to Calibrate a Torque Wrench

Disclaimer: I haven't used these particular instructions so YMMV. But there are lots on the net.