Need to install helicoil for one bolt hole in block for head bolt. After reading all the threads, it sounds like helicoils will leave a stronger hold and I would hate to do one and then install head and find that I have one or tow additional bolts that will not torque down correctly.
I will bite the bullet and get all new head bolts as well.
So, if you have to do one for sure, would you do all 15 while the engine is out of the car? Or is there some sort of test or inspection to do with head off and see how the originals are? Just sounds like it's going to happen to one or two holes somewhere down the road.
If I have to buy a kit with the drill bit and installation tools for one coil, they'll just sit in a drawer until I need them again. So the only aditional cost is the cost of the actual coils.
I'll hang up and listen.
If it ain't broke whey fix? Because of the softer iron used in earlier blocks don't over torque the head. 40 to 45 should be good for a stock engine. That and make sure the holes are cleaned out and check the fit of the bolts before installing head gasket.
And, if anyone has done a helicoil on a 26/27 block, do you have the NAPA part number? Do I just take a head bolt up to them and let them select a kit?
I've taken an old head bolt and cut a grooove down the threads to make a thread chaser out of it and am working on cleaning all the existing threads and holes with a welding rod as a pick and blowing out with compressed air. So far, I'm not feeling any really bad threads other than the one that Bubba tried to drill and tap and epoxy or something. That's the one I know I need to helicoil.
DO NOT use helicoils. They are too wimpy for this duty. Get in the McMaster-Carr catalog and find threaded sleeve inserts. They are far more robust and will withstand the rigors of head torquing multiple times.
(Message edited by Dan_Treace on February 07, 2016)
I would clean the bottom of the holes out and torque a head down on the block and only repair the holes that were defective. I think helicoiling all of them is over kill and probably will result in a weaker repair.
The problem is that everyone will have a different opinion as to what "you should do".
Last year I pulled the head on my 1910 to clean the water ports. When I reassembled the head one of the bolts stripped out. I went to O'Reilly Auto Parts with bolt in hand. They set me up with a helicoil kit that worked just fine. Upon inspection, I noticed that several of the holes had already been done so I went ahead and did the remaining holes. Now all of them have helicoils and I have not had any more problems.
Be sure to first install the head without a head gasket to be sure that the bolts do not bottom out before they touch the head. Then you can install the head gasket and torque the head.
Your mileage may vary...
The biggest issue with threaded inserts is alignment. Use a head to align the heli coil drill and whatever you can to align the tap. The holes in the head are just right for the drill. Don't assume either the drill or tap will follow the existing hole. When I did my 1910 block, I used solid inserts and placed the block in a mill to align the tap. Came out good but a lot of work. Problem with mine was someone repaired the bolt holes with heli coils and wasn't careful to align the holes. Had to start all over with solid threaded inserts.
Best ones use stakes at the sides to bed in the inserts. If you want top of the line inserts, check out Lock & Stitch in Turlock.
A customer of mine had this problem when fitting a Z head to his freshly rebuilt motor. The washers under the bolt heads meant there was even less thread engagement on the bolts. As well as cleaning out all the holes and running a tap down to clean the threads, I supplied him with a set of longer head bolts from a GM 6 cylinder motor common out here. These went to optimal depth, picking up previously unused threads.
Hope this helps.
Allan from down under.
IMHO a helicoil will do just fine and requires a smaller drill size than most thread inserts. As mentioned earlier with any insert your tap must be perpendicular to the surface.
The problem with opinions, is that they are just that. "Opinions", sometimes they can be backed up by facts? Sometimes not.
A couple of my opinions.
For what it is worth. The earlier (brass era) blocks are weaker. They need to be torqued not quite as high as later blocks. About 45 foot pounds for brass era (that is blocks, not cars with later blocks). About 55 foot pounds for starter era blocks. Between the two? Best guess between the two.
Like Allan B says. Check the length and fit of every bolt. Maximize the depth of the hole as best you can without compromising your ability to properly torque the bolts. Adapt longer bolts if you have to.
If it ain't broke, don't fix it. I generally agree with that. A couple of years ago, I was reworking two brass era blocks. One was to go into my "mostly '13 speedster". The other is still sitting on my shop floor for a future project. One of them (I don't recall which), needed two threads replaced. I chose to NOT repair any that were good. However, careful examination and fitting disclosed a couple more that were marginal. I think I replaced the threads in five of them.
I used Helicoils. Because I have used them before, and tests have shown the repair is probably going to be stronger than the original.
That said, James L III is probably correct. Threaded sleeve inserts probably ARE better. The fact is, it can vary based upon the thickness and quality of the castings involved.
I have also used heads as a guide to drill and re-thread straight. I once heard of a fellow that took a cracked head, and drilled out the needed holes to guide his taps (the drill for a Helicoil will likely fit through a regular head). As long as he had a few non-oversize holes left, he could use those to center the head straight.
Something I use. When cleaning out the bolt holes, if an appropriately set up air compressor is not readily available? Take about two feet of fairly small , flexible, plastic tubing. (I put tape on one end so I can keep track of which end to put my mouth on.) After scraping, and cleaning and first tapping of the threads. Either air compressor or lung exercises, blow out the hole, well. Then use a bottom tap (you are aware of various types of taps I hope?). Then blow it out again. DO NOT HAVE YOUR FACE OVER THE HOLE! (I looked really funny when I went in to wash my face!) (Smart guy? Aren't I?) That is why about two feet of FLEXIBLE tubing!
Again, most of that is my opinion, based upon experience and a few facts.
Good luck! Drive carefully, and enjoy, W2
To expand on one of Wayne's comments:
When I did my engine i cleaned out the block bolt holes as he describes, but I add the use of my shop vac. When I'd blow out the hole I'd have this shop vac nozzle right there. It was pretty effective in catching all the crud and preventing it from going where it's not wanted.
Search Stevens Tool T-235 and see the way to fix this problem. Look in the classified ads and forum Dan
The Stevens tool is the bee's knees.
Helicoils work great and are an easy fix for a stripped bolt hole. Here's how I have done it many times:
Great link, Royce. The duct tape covering the remainder of the block to keep the shavings out is a great idea!
OK, my intention is try a helicoil on the ONE hole that I know is messed up. dry fit the head and see if I can get close to the torque on the other bolts. If so, I'll reinstall a new gasket and replace the head. I've ordered all new head bolts from a supplier for this purpose.
If I have any issues with some other holes, the kit I purchased has enought coilds for 6 holes. I'll save them for possible future use or if another Model T owner needs to do one of these. I'll be happy to mail it out to borrown. It's a $26 set with no drill bit and will just sit around unless someone needs the other 5 coils.
I'll report back how the process goes. If I can do it, ANYONE can do it.
I have had good luck with helicoils. Make sure that you thread the helicoil down deep enough so that the top of the coil is below the top thread of the hole. That way the end of the coil will "dig" into the top of the hole, keeping the helicoil from backing out.
Also, since you are putting the helicoil into a blind hole, be sure to use a magnet or some gum on the end of a stick to fish out the bottom tang of the helicoil after you drive it off. That way, it won't sit in the bottom of the hole taking up space that the head bolt might need to reach full clamping force on the head.
Robert, Make sure when installing the Helicoil, you thread it 1/4 turn beyond the top surface. That insures that the insert will stay seated when engaging the bolt. Typically the kits come with three lengths of inserts. Choose the 1-1/2 or 2 diameter long insert as long as there will still be room to remove the tang after seating the Helicoil. Use the proper drill and STI tap (included with the kit) and you should be fine. As others have mentioned, use the head for your drill guide. Apply the same amount of torque on the head bolt going into the repaired hole as you do on the others.
I have successfully used helicoils on several head bolts on several cars.