Well if you caught my last post, my spark plug threads on my aluminum head are shot. Only one is shot but I want to fix them all while I have the heads off. I called the machine shop and they said that they would advise not using a heli coil because they can come out. He said that they use something else(didn't fully understand what) that is in there forever. Here is the problem: he wants $50 PER HOLE. Like I said, I would like to have all of them done while the heads are off but I don't have $400 growing out of my a$$ right now(or ever for that matter). Should I check other shops? Buy the do it yourself heli coil kit? I have never done these so I am a little worried about tearing into my nice heads. I wouldn't have a problem paying someone to do it right but not for $400. I knew this was going to be expensive one way or another :wall:
birdguy3
Call another machine shop for a second opinion. Also, if the other spark plug holes are OK, leave them alone. Good luck.
I dunno if this sounds stupid, but can't you drill out the damaged threads and retap for a bigger plug? Don't know if it can be done and not interfere with the piston travel or the combustion chamber efficiency, but for the price of a good tap, sure is cheaper.
A Helicoil is stainless steel wound into what likes very much like a coil spring. And no, it's not the best solution for spark plug thread repair. Helicoils work fine where the bolt will rarely be disturbed but spark plugs you expect to replace on regular basis. The Helicoils tend to come out with repeated use. I believe you are looking for "inserts". Like these . Pay particular attention to the "Ford frequently asked questions. I have used these type of inserts on motorcycle and old VW Bug heads and they worked just fine. If you're capable of removing and reinstalling the head yourself, you can fix the spark plugs threads yourself with one of their kits. It's not hard with the kit , just take it slow and follow the directions exactly. Theough I haven't actually used a kit from this particular company, what they are selling looks to be top-notch stuff. You can likely find something cheaper with some searching, if you want. This type of repair insert will generally outlast the head itself. In most case I would only replace the affected plug hole. But if you have another sparkplug that is particularly difficult to reach with tools if you wish to replace it you might consider doing that one too. Difficulty getting a spark "started" into the head is likely THE most common cause of buggered up threads. It certainly was in all case where I had to use this type of repair.
I prefer Keenserts over Heli-coils. You may want to check them out. http://www.keensert.com/keensert.pdf Page 52 shows the spark plug hole repair kits.
I too prefer the Keenserts. I last used them to repair the pivot points for my 67 vert top clamp handles.
When doing the spark plug holes, it's not critical to have the hole perfectly aligned...so doing it by hand is definatley an option. My guess is the $400 is for the machine shop to set is up and accurately locate and drill at the correct angle.
Dave
When doing the spark plug holes, it's not critical to have the hole perfectly aligned...so doing it by hand is definatley an option. My guess is the $400 is for the machine shop to set is up and accurately locate and drill at the correct angle.
Dave
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
