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I've got '85 4.9 that needs to have a manifold stud hole (female) threads renewed.It's close to the front of the block and easy to get to. I was wondering if someone could tell me how to install a helicoil and if the manifold would have to be removed to get good access to the head?
Thanks
smitty
A heli-coil kit comes with the correct drill bit, tap, an insertion tool and a few of the coils. You drill out the hole, run the tap in and then use the heli-coil tool (insertion tool) to screw in the coil. It is simple. I restore old CAT dozers as a hobby and had to install a ton in the cast radiator lid. I'd say remove the manifold so you can see that you are drilling straight, tapping straight and it will be easier to screw in the coil.
I appreicate all of the answers but if the hole has to be drilled out and retapped, why not just use an over size stud and skip the helicoil? The helicoil just restores the thread to the original size, right?
To me it is always better to have all the bolts the same, hence use a helicoil. If you use a larger bolt, you may need to enlarge the manifold hole. Of course if you never change the manifold it doesn't really matter.
Oscar, I trying to learn why you would use a helicoil. If it's to keep all the bolts the same size, ok, but you have to drill and tap for the helicoil, right? Is the tap for the helicoil a unique size? I just installed the manifold so everything should unbolt alright. I followed one of Fords recall bullitun(sp) and I'm not to sure about the no gasket part, seems like I remember a post where someone doubled the gaskets and it solved the warping and leaking problem. Anyone know about this?
Helicoil taps are a unique size. I bought different sized Helicoils from NAPA. You wouldn't have to drill out as large a hole as with going up to the next size bolt. You might be able to double gaskets and plug an exhaust leak due to warpage, but the gasket is the weak point. Have access to a mill or some way to machine the manifold back evenly? In the old days I guess you could hand scrape (same as scraping a head or Lathe bed) and use a straight edge to check alignemnt.
helicoil will not tap out as much metal as a new bolt/stud tap will. I think you won't have to drill at all - helicoil tap will start and tap out in the remaining threads of the old bolt.
If you have a problem with sealing -Try a Mr. Gasket #260 gasket. It's a little thicker than stock.
Depending on how hard a metal you're trying to run the tap into, you would want to consider drilling first with the supplied drill bit. No sense in forcing the tap and it is no fun breaking off a tap in a hole. Though taps are usually so hard you can break them up with a chisel to get the busted part out.