I recently replaced my beloved 91 f 350. She had 350,000 on her 5.8l and was still going strong. Body and ele. system was getting tired. Replaced her with 2000 Ex. 6.8l. Though I got a good deal 4500. out the door with 121012 on the clock. All was well til tuneup time. After tuneup started blowing plugs. Never heard of that happening. Started doing my homework and found this to be a common problem. Seems like an easy fix though, tap the hole and use a save-a- tread insert. I have done this to 2 holes 15 min. job. Blew plug num. 3 now comes the bad news. Previous owner must have this happen as well and tried to repair using wrong size insert. The treads in the plug hole are all bugged up and the right insert goes round and round. Since the temp here hasn't been above 30 since Dec. I used j.b. weld as tread locker and 2 weeks latter, so far so good. My question is does anyone know if you can go double oversize on the insert. Also if I have to replace the head can you use the 3v head on a 2v block as I've heard the 3v heads are almost garrentied not to blow plugs.

 

Ok you have a problem. I have seen (don't know if this is possible on yours) a pipe nipple cut to fit and taper threaded into a cylinder head. Then the pipe internals were cut to fit the spark plug. Short of something drastic like this I think a machine shop is your only choice or replacement head. Best of luck on this very difficult problem

 

Stop and contact Blownoutsparkplug.com

 

This is interesting. It is very similar to the taper pipe nipple end that I have seen used on a previous engine. The taper has better gripping force than the straight thread replacement. When I covered the pipe nipple this was to form the taper thread section. Then it would have to be internally threaded to match the plug. What was on the site was almost identical to the pipe nipple repair however more professionally done as we didn't have all the machine tools.

 

Whewww. Saw the thread title and thought I was gonna have to report an x-rated posting.

 

timesert has the repair for you.

http://www.timesert.com/html/bigsert.html

 

X2 on the Timesert, I use them in the shop. They are not cheap, but do work very well.

 

The 3v head wont be an easy bolt on. What I think you want is the later 2v head with the increased thread for the plug. There was an update on the later models, pre 2005 when the 3v came in. Or you could replace the whole engine and tranny with a 3v and torqueshift :-)

 

No need to replace head....usually ..Tmesert will repair permanently...