Stripped spark plug hole.....Helicoil or swap head?

[BonairII]

While checking plugs I noticed that my #1 cylinder spark plug hole is stripped. I def didn't do it...I'm guessing that the previous owner probably cross threaded it and weakened the threads, since there is another helicoil installed on the #4 cylinder.

Anyone know how difficult it is to re-tap the cylinder and use an insert (i.e. heli-coil, save-a-thread, etc)?

I have a parts motor, so swapping heads is possibility also. Where would I buy head gaskets for my 1967 Johnson 80hp?

 

[raczekp1]

Re: Stripped spark plug hole.....Helicoil or swap head?

i would pull the head of and go to repair shop.they will make a sleve and make wider thread in striped hole.screv in the sleve with new thread for spark plug.
easy and cheap and the best solution

 

[BonairII]

Re: Stripped spark plug hole.....Helicoil or swap head?

go to repair shop.they will make a sleve and make wider thread in striped hole.screv in the sleve with new thread for spark plug.

That's what a helicoil kit does. It comes with a tap and sleeves. If I've got to pull the head anyway, I guess I might as well order the head gaskets and do the swap.

 

[Exotic4x4]

Re: Stripped spark plug hole.....Helicoil or swap head?

Problem with helicoils is there is a part of the winding that is in the bottom center of the.helicoil, yes u could grind it off after its installed with the.screw in tool, if u didn't remove it the electrode.on.the.spark plug would hit the coil winding in the center,I would honestly take it to a machine shop have them turn and thread the I.d and or the o.d of some stainless or heat treated steel and either press it in or like I said make a beefier helicoil. and install it make it heavier duty. As a machinist that's my .02$

 

[BonairII]

Re: Stripped spark plug hole.....Helicoil or swap head?

Problem with helicoils is there is a part of the winding that is in the bottom center of the.helicoil,

I'm not sure what you are referring to. I just replaced a 'save a thread' insert on the port side(the insert was stuck to the plug). The insert simply screwed in.

Regardless, it seems that it'll be easier if I just swap heads. No sense of spending the money on having a insert professionally done if I'm going to have to pull the head and replace the gasket anyway.
Is this the only gasket that I'll need?
http://www.marineengine.com/newparts/part_search.php?part_num=306048&x=17&y=13

 

[JB]

Re: Stripped spark plug hole.....Helicoil or swap head?

There are 2 advantages to TimeSert. 1.) It is an alloy that conducts heat about the same as the alloy head (you won't need to find a cooler running plug), and 2.) It is bonded to the head by stretching it. It won't fall out like some other products.

If you have a replacement head with plug threads in good shape that is by far the best solution.

 

[BonairII]

Re: Stripped spark plug hole.....Helicoil or swap head?

Anyone happen to know the pattern to tighten the head bolts? And to what torque?

 

[clanton]

Re: Stripped spark plug hole.....Helicoil or swap head?

I have used Time-Sert for 40+ years, work great. Local Kawasaki dealer may have them.

 

[retiredfornow]

Re: Stripped spark plug hole.....Helicoil or swap head?

Timecerts are great! Trouble is, where does the shavings go when you're tapping a spark plug hole?
I've greased the tap to catch them, then grey taped a hose to a shop vac that would fit thru the plug hole. Pull the head, then no problems. Good luck.

 

[Monte1961]

Re: Stripped spark plug hole.....Helicoil or swap head?

Heres a trick if you deside to do the timecert thing. 1st. before drilling, apply grease to the drill bit. This will help in traping shavings allowing them to stick to the grease as long as you dont drill it at high speed! The trick is go slow!!!!!! You will also have to use new tap that comes with the kit you will need to purchase. When tapping, use grease on the tap as well, same thing!!. Now you will also have a countersink cutter as well. Same thing use grease! Before you install timecert, make sure you use the best quality thread lock you can find!! It sounds worse that it really is! I have used then on various applications and with great success! If you want to make sure that there is no shavings inside, remove head first as mentioned above. Post back your results and let us know how you made out!

 

[BonairII]

Re: Stripped spark plug hole.....Helicoil or swap head?

Would it be smart to just change both heads/gaskets at this point? There's a 'save a thread' in the starboard side cylinder right now and I'm thinking that I might as well change both so I don't have probs in the future with it.

I've never pulled heads before... what are the chances that the bolts will actually come out without breaking off?

 

[Monte1961]

Re: Stripped spark plug hole.....Helicoil or swap head?

If just used in fresh water then pretty good. If used in salt water the not so good! PB blaster might help and also some heat used as well! Good luck! Just for reference. when you buy a timecert kit, it will come with a few extra. The other shop moto is, if it works, don't fix it!

 

[BonairII]

Re: Stripped spark plug hole.....Helicoil or swap head?

I'm not going to buy an insert kit. Just going to swap heads from my parts motor.

 

[boobie]

Re: Stripped spark plug hole.....Helicoil or swap head?

Good idea.

 

[yorab]

Re: Stripped spark plug hole.....Helicoil or swap head?

Be sure to clean up the threads on the "new" heads to prevent excess friction that could lead to stripped threads, thereby putting you right back at square 1.

 

[jimbo_jwc]

Re: Stripped spark plug hole.....Helicoil or swap head?

My trick to collect drill and tap shavings when installing Helicoils is with grease on all tooling plus I magnetize all of them . Also break screwing tab off before putting in with permanent Locktite . Most were 14mm and they have held up to numerous plug changes never pulled heads or had problems w/compression . Helicoils are high carbon steel and some stainless . Also micro dot of neverseize on plug threads and choke up on ratchet when installing . Recheck tightness after running . Only ones that ever where loose was in a RX7 motor.
Anybody that has had one of those motors relize why you dont park them in your yard or hay feild .

 

[Exotic4x4]

Re: Stripped spark plug hole.....Helicoil or swap head?

Aluminum isn't magnetic.... Also helicoils are not carbide or carbon steel carbide is an alloy that is heat treated to give it its strength, and also when installing helicoils u want to use thread lock they have the same right hand threads as a standard bolt...if u over torque urs plug the helicoil would come out with your plug....jimbo where are you getting this info...read my above post on helicoils,I work with this type of thing everyday and highly disagree with your above stated post further more you cannot.break threading tab before installing helicoil if you wanted to go this route you'd be unable to install it. And rx7 motors I didn't think.related.to outboards

 

[crackedglass]

Re: Stripped spark plug hole.....Helicoil or swap head?

I've used Heli-Coils for over 30 years, if installed correctly they are no problem at all. They are not the solution though for tapered seat plugs.
As far as I know Heli-Coils are made from stainless steel.
The little tang is designed to break off when twisted backwards, which I've always done with a pair of needle nose pliers.
I've got a few motors with Heli-coils that were done 30 years ago and never an issue.
I've got both Heli-Coil and insert type repair kits and use both but both have their place.

A vacuum cleaner and small hose can be used to make sure no chips are left in the motor.
I grease the tap, which also cuts the oversize hole, no drilling required with a Heli-Coil. It's a stepped tap that reams and cuts new threads in on pass. I usually use white lithium grease, it seems to hold the chips better. I also back the tap out several times as I wind it through the bad plug hole removing chips each time.
Again, if you have a spare head, that's the easy fix but a Heli-Coil is certainly do able.

 

[BonairII]

Re: Stripped spark plug hole.....Helicoil or swap head?

Ordered new gaskets today. I was pleasantly surprised that the head bolts came out with unbelievable ease! They weren't loose, but I was surprised that it took very little effort break 'em free. 1/2 turn with the wrench and took them out with my fingers the rest of the way. Both heads were easy. I'm guessing that the PO's mechanic had the heads off at some point cause the gaskets were in great shape.

The starboard side had a "film" on the water jacket opening(see pic), but it fell right off with ease. Both cylinders are smooth as a babies butt, No scoring at all. Ports are clean(just a small spot or two of carbon).

starboard side

Port side

 

[jimbo_jwc]

Re: Stripped spark plug hole.....Helicoil or swap head?

Aluminum isn't magnetic.... Also helicoils are not carbide or carbon steel carbide is an alloy that is heat treated to give it its strength, and also when installing helicoils u want to use thread lock they have the same right hand threads as a standard bolt...if u over torque urs plug the helicoil would come out with your plug....jimbo where are you getting this info...read my above post on helicoils,I work with this type of thing everyday and highly disagree with your above stated post further more you cannot.break threading tab before installing helicoil if you wanted to go this route you'd be unable to install it. And rx7 motors I didn't think.related.to outboards

Sorry missed OB part just ranting and rave move point . Iron and Steel only advice