horseman with no horse 26 #1 Posted August 30 i was doing intake gaskets with my buddy and i noticed the threads were pretty gooped up on one of the intake port bolt holes. it still has 2/3 of its threads so i just sent it. it runs good and thats how it was when i got it, but i still want to fix it. what size are the original threads? i kinda just wanna run the next size tap in it and put a fresh oversized bolt in it. would heli-coiling be a good option? Share this post Link to post Share on other sites
ri702bill 8,387 #2 Posted August 30 A Helicoil is a good choice, because if done properly, it restores the original thread with a stainless insert - better than OEM. But, done wrong .... get out the big checkbook... Share this post Link to post Share on other sites
rmaynard 15,535 #3 Posted August 30 I Heli-coil'd my P-216 intake holes and it has been working great since. Share this post Link to post Share on other sites
horseman with no horse 26 #4 Posted August 30 would it be a bad idea to just tap it to the next size threads? Share this post Link to post Share on other sites
lynnmor 7,321 #5 Posted August 30 The thread size is 5/16-18. On a number of the intake and exhaust screws it is possible to tap them deeper, use a bottom tap and go as far as you can and then get longer bolts, cut to fit is a good idea to get maximum engagement. I do this any time I have those bolts out to prevent what you have experienced. A drop of oil on the threads and torque to no more than specified. 2 1 Share this post Link to post Share on other sites
horseman with no horse 26 #6 Posted August 30 what size tap would i use to put an over sized bolt in it? i dont know what the next size up would be Share this post Link to post Share on other sites
Ed Kennell 38,329 #7 Posted August 30 55 minutes ago, lynnmor said: use a bottom tap and go as far as you can To get max thread engagement, you could double nut a threaded rod and turn it in tight with loctite. Then saw it off at the correct length to fasten with a hex nut. If the threads are too bad for this to work, 8mm would be the next size bolt. 5/16=0.312" 8mm=0.320". 1 Share this post Link to post Share on other sites
ri702bill 8,387 #8 Posted August 30 Next up size - 3/8-16 UNC. Why not M8?? Way tooo close in size and the wrong pitch..... No actual good bite on boogered up threads.....My 2-1/2 cents... 1 Share this post Link to post Share on other sites
Bill D 1,927 #9 Posted August 30 You can't go up to the next size. The bolt won't fit thru the intake manifold. Helicoil or use longer bolts. 1 Share this post Link to post Share on other sites
horseman with no horse 26 #10 Posted August 31 4 hours ago, Bill D said: You can't go up to the next size. The bolt won't fit thru the intake manifold. Helicoil or use longer bolts. what tap and heli coil should i use? Share this post Link to post Share on other sites
Bill D 1,927 #11 Posted August 31 The helicoil set should come with the necessary tap. Bolt size is 5/16"-18. Share this post Link to post Share on other sites
ri702bill 8,387 #12 Posted August 31 54 minutes ago, horseman with no horse said: what tap and heli coil should i use? The "kit" is the way to go. Comes with a few Helicoils, special drill and tap - AND the driver to wind them into place. Not cheap, but do it right - there are YouTube videos on how to do this... 1 Share this post Link to post Share on other sites
horseman with no horse 26 #13 Posted August 31 alrighty it seems you guys like the heli coil route. does anyone know what the kits part number is? Share this post Link to post Share on other sites
pfrederi 17,743 #14 Posted August 31 5/16 NC Kit part # 5401-5 Share this post Link to post Share on other sites
horseman with no horse 26 #15 Posted September 1 5 hours ago, pfrederi said: 5/16 NC Kit part # 5401-5 https://skygeek.com/heli-coil-5401-5-thread-repair-kit.html is this the correct kit? Share this post Link to post Share on other sites
onanparts.com 181 #16 Posted September 1 1 hour ago, horseman with no horse said: https://skygeek.com/heli-coil-5401-5-thread-repair-kit.html is this the correct kit? Normally I would say buy the name brand....but...this one is under $16.00 and no 45+ days lead!!!! search Amazon for this: BILITOOLS 5/16-18 inch Thread Repair Kit, HSS Drill Helicoil Repair Kit SAE Using the Helicoil brand USA made inserts is preferred. Share this post Link to post Share on other sites
RED-Z06 2,221 #18 Posted September 2 Another option is stud it all the way to the bottom, use a nut on top. 1 Share this post Link to post Share on other sites
