WadeLovell

iTrader: (5)

I had to thread chase the #1 cylinder sometime in the last 3,000 miles because when I changed spark plugs the bottom two threads of the #1 spark plug were filled by a coil of aluminum -

So, I brought it up to TDC, chased it, vacummed the shavings (hard to do without removing the throttle body, etc.), shot in some compressed air, and went about my business.

I am replacing the head gasket today. Should I helicoil while she is apart or continue with the remaining factory threads? Obviously, if she ever blows that spark plug I will be banging my head against the wall.

Thanks,
Wade

WadeLovell

iTrader: (5)

Seriously, no one has an opinion on this?

I expected _________ to say, "If you ever want to make serious HP then don't do it. If it is busted have it welded and retapped". I thought _________ would say, "If the plug cinches down to spec, leave it until it blows out of its hole and then fix it". I knew __________ would say, "Fix the bloody thing. The head is already off. It takes ten minutes. After you button it up and the spark plug blows, because you installed a new head gasket and increased the compression, it will take eight hours to do it right. Save yourself the headache!"

INTIMAZY

iTrader: (5)

Not sure if this helps at all or is relevant to you but I used a timesert on a modular aluminum head 4.6 Mustang motor and it lasted less than 6 months before it failed and blew out on an otherwise stock motor. Somewhat similar in concept to a helicoil.

Ended up buying a junkyard head, redecking it and throwing it on 2 weeks ago. I should have just done this in the first place.

That being said, of the two options you listed, if the head is off, HELICOIL!!! It's cheap insurance and distributes load across the thread better.

Vwpride12

Ask the machine shop that pressure checked the head what they would do.

WadeLovell

iTrader: (5)

Thank you. The shop thought I would be better off not using the helicoil and recommended if the threads fail that I look for a rebuilt head rather than try to repair this one. I will thread and torque carefully!

Kind regards,
Wade

Ali SC3

iTrader: (10)

The stock threads won't really fail if you torque the plugs correctly so its not necessary unless the threads are already semi shot.

drft_n_sc

iTrader: (3)

I used helicoils on my stripped exhaust manifold bolts about 4 years ago and to this day they have been holding up perfectly!!

I say do it!!

WadeLovell

iTrader: (5)

I decided NOT to helicoil. I have had mixed luck with them. I pulled the head off to replace the head gasket and used the opportunity to chase the threads. The threads are semi-shot but I tested that they held the correct torque before making the final decision. Unfortunately, I pulled the plug yesterday to check compression in the #1 cylinder and, when my newly decked head arrives and I remove this one, I will helicoil before putting it on the spare parts shelf.

apexpro

For high(er) pressure use like sparkplugs in cylinder heads I've had better luck using timeserts than helicoils.

(no affiliation) http://www.timesert.com/html/sparkplug.html