Stripped intake manifold threads

McJeeper

The rearmost driver's side intake manifold bolt stripped out of the head on my 304. I installed a new intake gasket and that bolt stripped way short of the 43 lb/ft I was torquing to. What's the best way to fix this? Is there enough material in the head to drill and tap that bolt out to 7/16"?

jeepsr4ever

If its accessable a heli-coil is in order. If it isnt then you may be stuck either trying a longer bolt or taking the head off.

McJeeper

I've heard of and seen Helicoils for years, but never used them before. Is the benefit that it doesn't require oversizing the hole? Is it possible to install it without removing the intake manifold again? Thanks for the help.

fifesjeep

Helicoils SUCK!!!! Eventually they twist out etc... If you want something that's Kick-ass use KINGSERTS!! A.k.A. Key Locking Inserts!!!
Check them out here is the site:
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=000000039767081
Type In Key Locking Inserts

McJeeper

I wish I had seen your post earlier. I put in a Helicoil this morning. It didn't feel great when torquing the bolt in, but I went to 40 lb/ft and stopped. Hopefully it holds. The hole I had to drill for the Helicoil was actually 1/64" larger than I would have needed to tap it out from 3/8 to 7/16. I'm wondering if the insert was the way to go at all. Time will tell... Thanks for your help.

Wrench Man

fifesjeep wrote
Helicoils SUCK!!!! Eventually they twist out etc...

You're putting them in WRONG!, they are THE! thing for fixing threads!
If you use the CORRECT drill bit and tap the hole properly they are STRONGER than the original threads!, I've installed more than a hundred at the machine shop with EXCELLENT results!

fifesjeep

Wrench Man wrote
fifesjeep wrote
Helicoils SUCK!!!! Eventually they twist out etc...

You're putting them in WRONG!, they are THE! thing for fixing threads!
If you use the CORRECT drill bit and tap the hole properly they are STRONGER than the original threads!, I've installed more than a hundred at the machine shop with EXCELLENT results!

=D> It isn't hard doing helicoils, especially when the kit comes with everything needed. Install tool, drill and tap... 111!!! There just not good for torquing on... There good for snugging things up... Especially the smaller bolts...

they are THE! thing for fixing threads!

You obviously never used Kingserts (Key Locking Inserts)... Here's a test for you, Put a Helicoil in an open hole and put a 1/4"-20tpi grade 5 bolt in it and make sure the threads stop 1/4" from the hex... Run it down and once the threads run-out torque on it... What happens???? Now do that with the helicoil in the closed hole... Check the results and write it down... Now use the Kingserts.... :mrgreen: I gaurantee if it's a 1/4"-20tpi grade 5 bolt and you wrench on it with the kingserts installed you'll twist the grade 5 in-half :idea:
Helicoils are good for minor "stuff" I've worked in a few Machine shops, Civilian and Military... Helicoils go out the door for the "Non-important" jobs. If grinding the threads out to a minimal of 22.5* (per side) and weld filling then machining isn't needed we use Kingserts... The reason most peopl don't use them is ONE... they don't know about them and never worked with them first hand or TWO they're too expensive and don't want to spend the $$$ for the quality product... I used to be all about Helicoils until I used the Kingserts... I actually tested them at a Convention out in LA back in the day... From there I was hooked... every-place I go I make sure I have Kingserts... Give it a shot, you'll see what I'm talking about.

Wrench Man

I've used them, in air cooled VW and Porsch spark plug holes of all places, but I'll still take the HeliCoil any day!

tufcj

I think the problem is that he's over torquing the bolts. Those are only 3/8" bolts. Just a quick look in my 68/69 service spec book says the intake bolts should only be torqued to 20-25 lb/ft. Where did the 43 lb/ft number come from? That seems too much for a 3/8" coarse thread bolt. BTW, I've used Kingserts and Helicoils (use true Helicoils, not cheap knock-offs). I've never had a Helicoil back out or strip in aluminum or steel. Bob tufcj

jeepsr4ever

I have had great luck with Heli coils but have had a few windout...probly from botching the tap jobber.

AMX69PHATTY

One thing to watch on Intake mounting bolt is that they don't bottom out in the tapped holes in the heads before they actually clamp down tight on the Intake Manifold. The taps in the heads are only so deep, so if the Intake mounting bolts are a little long they will run out of threads in the head's tapped holes before they clamp on the intake manifold, and in tightening further they tend to want to strip out the hole, especially if the bolts are just a lttle bit too long. With the intake off screw all the intake mounting bolts in to head holes, go around with a caliper and check the under head distance on all the bolts, then go to the intake and measure the mounting flange thickness, include washer thickness if used, and confirm the bolts clamp the intake down before bottoming out in the cylinder head tapped holes. Have had to grind down the length of intake mounting bolts before that were a little bit too long. Especially if the intake has been machined to fit between heads that have been milled. :-|

1980_Cj7

I wouldn't worry too much about one intake manifold bolt. Heck, if you seal it right, with the "right stuff" (pun intended), you'll be fine. When I had to pull our intake after only 300 miles, I swear I could have picked up the whole Jeep by the intake manifold...with all the bolts out! It was a real pain to get loose, but that's a good thing. It was sealed really good. I used Permatex Right Stuff around the water and exhaust openings, and the front and back ends and Hylomar around the intake openings. Both sealants were used on both sides of the tin valley pan gasket.