Stripped spark plug hole
Melting Slicks
Joined: Jul 2019
Posts: 2,009
Likes: 850
From: FL Keys
2025 C5 of the Year Finalist - Unmodified
http://castingrepair.locknstitch.com...thread-inserts
Look into these thread repair kits. They are the best out there. If not your choice, pull the head.
Look into these thread repair kits. They are the best out there. If not your choice, pull the head.
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,597
Likes: 7,046
From: New Or-leens Loo-z-anna
If the reading is getting smaller, the piston is approaching T.D.C. Remove the dial caliper and bump the engine again and take a reading. You want to get the smallest/shortest reading u til the reading stays the same after bumping the starter....the pizton has reaced the highest point.
Carefully measure the depth again with the dial caliper tail...this will be the approximate length fron the surface of the spark plud hole to the top of the piston (it doesnt matter if the piston is on the exhaust stroke as long as the piston has reached the top of its travel.
You will need a new spark plug about .030 SHORTER than the final reading you took with the dial caliper tail.
IF YOU ARE UNSURE about your accuracy in the final reading...allow a friend who is familar with dial calipers do the measuring for you so the piston top does not get damaved be ause the spark plug is too long.
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
i would pull the head as well. but OP is reluctant. he or prev owner may have been using a too-short plug when thread got hurt. it is a 462624 head. cheap and common. but these are not daily drivers. see what you need before buying parts. once one head comes off, replacing the pair must be considered. maybe ask bucaneer if any aftermarket or other replacement heads work well with crossfire. i know vortecs do not. the intake will not fit.
Last edited by nitan2k; Apr 20, 2022 at 10:14 AM.
Burning Brakes
Joined: Jan 2003
Posts: 961
Likes: 275
From: Frederick MD
If these are OE iron heads I would view this as an opportunity to put the frontend of the car on a diet. I would also view it as an opportunity to perhaps increase the performance alittle. Make lemonade????
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,171
From: Hermosa
I fail to see how using a 3/4" reach plug in a 1/2" reach hole is going to accomplish anything. The plug uses all of the threads in the hole. Maybe one left unused? In any case if the threads are gone in the hole then that's it.
Maybe the threads are damaged on the plug and not the head? Try a new spark plug in that hole or at least a different one or different brand. It may be an easy fix. If it's still loose in the hole then it will need fixed. Personally on an old high mileage engine with original heads I'd try the heads on approach vs pulling the heads.
Maybe the threads are damaged on the plug and not the head? Try a new spark plug in that hole or at least a different one or different brand. It may be an easy fix. If it's still loose in the hole then it will need fixed. Personally on an old high mileage engine with original heads I'd try the heads on approach vs pulling the heads.
Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
I fail to see how using a 3/4" reach plug in a 1/2" reach hole is going to accomplish anything. The plug uses all of the threads in the hole. Maybe one left unused? In any case if the threads are gone in the hole then that's it.
Maybe the threads are damaged on the plug and not the head? Try a new spark plug in that hole or at least a different one or different brand. It may be an easy fix. If it's still loose in the hole then it will need fixed. Personally on an old high mileage engine with original heads I'd try the heads on approach vs pulling the heads.
Maybe the threads are damaged on the plug and not the head? Try a new spark plug in that hole or at least a different one or different brand. It may be an easy fix. If it's still loose in the hole then it will need fixed. Personally on an old high mileage engine with original heads I'd try the heads on approach vs pulling the heads.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
tdc on #3. 18436572. 1-8-4 and 3 are 90 degrees apart. so when #1 is at tdc, #3 is halfway back up. so, turn crank 1/4 of a turn when you see tdc mark. are either valve cover off? when exhaust rocker is just closing and intake opening, cyl is at tdc. so when #3 or 2 have both valves moving, 3 and 2 are both at tdc. .
Team Owner
Joined: Mar 2002
Posts: 44,677
Likes: 1,830
From: Huntsville AL
Longer plug and JB Weld is your option at this point or pull the heads. There is no way a valve will fall into the engine or hit the piston by replacing the heads.
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Thread Starter
Racer
Joined: Oct 2021
Posts: 436
Likes: 15
From: Maryland
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
and a 14 mm 6 point socket. and if it slips, hammer a 12 point 13 mm on them. also, there is a taper at the bottom of most sockets. grind it off so the flats grab more of the bolt head and set the socket on with a hammer. i had a lot of practice with salt water corroded bolts on boat engines. you guys ain't seen nuthin!