Spark plug threads

mattybpt · Post by **mattybpt** » Fri Aug 03, 2012 12:11 pm

I'm new to the forum, and was hoping for some advice. I was replacing the spark plugs on my 1969 Dream and applied to much force and caused slight damage to the threads on the engine block. Any suggestions on the best way to repair this problem? Thanks

Goodysnap · Post by **Goodysnap** » Fri Aug 03, 2012 1:09 pm

The best way would be a good used or new head.

However, helicoil may be an option.

Goody

Ford Guy · Post by **Ford Guy** » Fri Aug 03, 2012 9:37 pm

Ok Dumb question here. On my CL head the spark plug threads are actually ferrous metal cast in the aluminuim head. That being said one could easily just run a chaser through the threads. So my question is Is the Dream head different? By the way if a Heli Ciol is installed correctly they are fine. There are also other spark plug inserts made that work very well

Shiny side up

Jon

Goodysnap · Post by **Goodysnap** » Fri Aug 03, 2012 9:53 pm

Ford Guy wrote:Ok Dumb question here. On my CL head the spark plug threads are actually ferrous metal cast in the aluminuim head. That being said one could easily just run a chaser through the threads. So my question is Is the Dream head different? By the way if a Heli Ciol is installed correctly they are fine. There are also other spark plug inserts made that work very well

Shiny side up

Jon

Not being able to see how damadged the threads are it's anybody's guess weather the threads are saveable or not.

All of these suggestions are options however the risk of shavings entering the cylinder are a major concern during these methods and removal of the head for heli coil or insert is in my opinion necessary.

If the threads are chased and it holds torque I would proly let it ride.

The best option if the threads are damadged beyond chasing is replacement.

OldHarley · Post by **OldHarley** » Fri Aug 03, 2012 10:34 pm

Good answers above, but I would suggest if the OP is unable to even change spark plugs without causing substantial damage to the motor, he should find himself a good motorcycle mechanic.

Ford Guy · Post by **Ford Guy** » Sat Aug 04, 2012 6:31 pm

Goody I agree with you. I am a service manager at a Ford dealership. We ream,tap, and install inserts on a regular basis with the heads on the vehicles. The big trick is to use grease on the flutes of the drills and taps. The grease will catch the vast majority of the chips and shavings. We then blow a fair amount of brake clean in then blow the cylinder out with an air nozzle. The brake clean dries up the aluminum and pretty much all of will come out. We have yet to have to remove a cylinder head or have any problems doing these.

Goodysnap · Post by **Goodysnap** » Sat Aug 04, 2012 9:49 pm

Ford Guy wrote:Goody I agree with you. I am a service manager at a Ford dealership. We ream,tap, and install inserts on a regular basis with the heads on the vehicles. The big trick is to use grease on the flutes of the drills and taps. The grease will catch the vast majority of the chips and shavings. We then blow a fair amount of brake clean in then blow the cylinder out with an air nozzle. The brake clean dries up the aluminum and pretty much all of will come out. We have yet to have to remove a cylinder head or have any problems doing these.

Yeah, done a ton of the 4.6, 5.4, 6.8's myself. I have used a shop vac with a small hose attachment and then double check with the videoscope. I have also heard of guys filling the cylinder with shaving cream. Keeps the shaving near the hole.

I have never installed an insert in one of these 305 heads. As long as a good thread locker was used it would be a good repair.

He asked for the best option. In my opinion if the threads are ruined, replacement is the best repair. Not necessarily the cheapest.