Performer RPM carb stud holes through into runner?

[drdano]

Had to fix some threads on my intake and noticed each carb stud hole was drilled into the runners.  Is this common with what others see with theirs?

Or, more likely, was mine machined by the same ace factory machinists that drilled my left side pushrod tubes .100 too high, milled the left valve cover rail .030 too high and drilled the distributor hole so far off its in a different area code?   

Whats best to seal the studs with to prevent ant potential vacuum leak?  thread tape, rtv?

[machoneman]

I use Loctite's 565 thread sealer. Won't harden like thread lockers. Many intakes, not just Ford or aftermarket FE Ford, suffer from carb holes drilled too deep. The same applies for rocker arm studs in many aftermarket aluminum heads.....meaning it's important to use a thread sealer here too.

http://www.gluemytruck.com/HENKELthread.pdf

[thatdarncat]

Although it sounds like there were plenty of "challenges" with that manifold, it may have the holes drilled on purpose. Some FE's used a hollow carb stud as a vacuum port. See the photo and link.



http://www.dearbornclassics.com/carburetor-stud-hollow-for-intake-vaccum-fairlane-mustang-torino-1968-1969.html

[machoneman]

True! Old and I mean really old GM '50's engines (Oldsmobiles, Buick nailheads, etc.) also used the hollow carb stud for vacuum operation of heater doors, wipers, etc.  A pal I helped with a '53 Buick rebuild back in the late 70's had missed this point and man, that engine on initial start up whistled loudly like you can't believe! 

[drdano]

Definitely learned something new here!  I thought it was just plain ridiculous that they'd drill in an extra 2.5" on some holes all the way into each runner underneath, so here must be the reason.  Thanks for the info folks.  And I'll pick up some of that locktite thread sealant.

[jayb]

FWIW I checked two of my Performer RPM intakes and on both, the front right carb stud hole goes through into the runner underneath.  Sealant is your friend...

[drdano]

Interesting.  All four of mine went all the way through.  Four extra vacuum sources, yay!   I did pick up some thread sealant and got the job done.  All four threads were pretty trashed out from years of carb swapping, so I bit the bullet and installed Keen-Serts in each hole.  I'm pretty impressed with them, they are super stout and I can't imagine short of using a breaker bar would cause the insert to rip out or move at all.

[Marx427]

I just received a High Riser 1x4 (C4AE-E) I purchased from a member of this site and on inspection found that the left front stud went through into #6 runner ...........?   

After happening onto  this post, I looked again and there are no other vacuum sources drilled
at all ......I'd never heard of the drilled stud.....so that's great info.