'86 350

Well, I finally found the vacuum leak on my engine i've been trying to track down for about a year. After trying everything else to no avail, I pulled the intake off since I had to drill it for helicoils for the carb studs, and I found this:






For those who can't tell, that's a hole straight through from where the carb stud goes into, right into the intake runner. It appears the previous owner drilled for helicoils as well, and went all the way through. Both of the left rear holes go through into the intake runner.

My question is, is there anyway to fix this? Would Teflon tape on the carb studs or sealant or anything be worth trying, or should I just pick up another Performer? I don't want to end up putting this intake on, only to find out the leak is STILL coming from there, and then have to pull everything off again to throw on a new intake.

-Thanks, Brandon

Vader

Get some 5/16-18 (or whatever thread they were sized to) hex socket set screws about ½" long. Apply a good layer of LocTite PST or Pro-Lock thread sealant, then install the screws to a depth which will clear the carb flange and gasket. If you are nervous about using set screws (which theoretically could thread down in and get ingested, but never should move once the PST is cured) machine the unused mounting holes with a countersink and install flat head cap screws. If you ever really needed to, you could remove the screws and use the threads. You may have a little trouble using a countersink with the thread inserts in place, but you can screw in new thread coils if necessary.

The oher option is to weld them shut and start over, if you have a TIG available.

afida15

jus buy a performer. waht are they like 130 bucks or something.

'86 350

As nice as it would be to be made of money, why spend $130 if I don't have too?

Supervisor42

I don't like helicoils. (donning asbestos underware for flames)
If there is room around the hole, use a KEYSERT instead. They seal better, won't unscrew, and will hold more torque than helicoils.

Damon

I'm with Vader on this one. An allen-head (hex head) set screw with some Loctite or similar on it should NEVER move again once it dries- and it'll seal up just fine.

I feel you on those bizarre vacuum leaks. Feels good when you finally nail it down and suddenly...... "Oh, look how smooth it idles now!!!! I guess the cam wasn't as big as I thought it was!"

Remember to reset your idle mixture screws and idle speed after you fix it. They will almost certainly want to be set different than you've got them now with that big hole sucking in air.