Originally Posted by 7.3Lariat
Thanks for the replies. I guess my original post wasn't very clear. I want to get it done in the manifold for sure. My question is can it be done without welding. How thick is the manifold, ie is there enough to be able to hold the probe in?
Yes, no welding required. Mine has been tapped directly in the manifold since 2001 without any problems. I recall the material is about 1/4" thick. It's enough to hold the probe.
As you are aware you need to find an area that is deep enough for the length or the probe. Mine is at the bend where the manifold is widest. I was also careful to tap as shallow (narrow) as possible so more threads would be exposed outside of the manifold rather than inside. This gives you another chance in the future to re-tighten the probe if it gets loose from heat/cool cycles, and it might loosen a a little bit a couple times till it sets. Mine did.
When the engine is cold you might feel the probe is the tiniest bit loose until you snug it up a little after first install. Never really got loose and never was a problem.
Work slowly and cautiously. Try to recover any metal chips by using grease on the drill bit and tap then use a shop vac to make sure no chips are in the manifold.