I own a 90 Red Vette. One of my spark plug holes are stripped out. A guy wants to charge me $1256.00 to fix it. He says he has to remove the head and re-thread the hole using a heli-coil. Someone else mentioned it should be able to be done without taking the head off. My cousin and I are engine savvy. What should I do?
I hope that you accidently typed a "1" in the quoted price. The only correct way to helicoil the spark plug hole is with the head off the engine block in a machine shop environment. The aluminum L98 heads have angled plugs so you don't want to screw this job up by guesstimating where to drill for the placement of the helicoil insert.
I would take the head of your Vette, take it to a good machine shop, and have them do the work. If you have to drive the car somewhere for whatever reason, be sure to disconnect the injector harness of the cylinder affected so you don't have unburned fuel washing down your cylinder walls and accumulating in your cat.
You have an aluminum head, check into repairing it without taking the head off using a heli-coil. Aluminum heads are easy to mess up but they're easy to repair too. Just bring the piston to TDC and vacuum out the combustion chamber with a small flexible tube attached to your shop vac to remove the aluminum shavings after tapping and before the insertion of the heli-coil. Do a search on the internet for "spark plug thread heli-coil" for more info. Should cost less than $50 if you do it yourself...good luck!
This type of repair is done all the time with the head still on the engine. Aluminum is very soft and if any is left in the cylinder, it won't damage anything. It will either burn (yes, aluminum burns) or will get taken out the exhaust.
Just bring the piston to TDC and vacuum out the combustion chamber with a small flexible tube attached to your shop vac to remove the aluminum shavings after tapping and before the insertion of the heli-coil.
I used Timeserts on my 3d Gen Lightning after spitting a few spark plugs. I installed them in each of my plug holes without pulling the heads and never had a problem. The 3d Gen Lightning boys swear by them and some of those guys are running lots of boost. Remember to go to TDC AFTER boaring and tapping. If you are TDC when you start, the seat cutter may hit your piston. Also use grease in the flutes of the cutter to collect the aluminum shavings. The entire job should take less than an hour if you go this route. Good luck.
I own a 90 Red Vette. One of my spark plug holes are stripped out. A guy wants to charge me $1256.00 to fix it. He says he has to remove the head and re-thread the hole using a heli-coil. Someone else mentioned it should be able to be done without taking the head off. My cousin and I are engine savvy. What should I do?
If it is an aluminum head then I do not recommend a Heli-Coil as that will have an affect on the spark plug's efficiency. There are aluminum inserts that we use but it does require the head to be off the engine.
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Chris C.
A.H.M. Performance
Baltimore, MD
Corvette Store
Spark plug hole stripped out. What to do?
