Input Wanted: Stripped Spark Plug Threads

Detroit Iron · Nov 26, 2014

I've got a brand new set of Edelbrock E-street aluminum heads in my '64 Polara 383. I managed to strip the #3 spark plug hole. I attempted to clean-up the threads with a spark plug thread chaser, but that too would not lock on to the original threads. After much effort at recovery; the hole is completely wrecked.

At this point, I need to repair the threads and that's why I'm here. I would like input on repairing the threads while the head is on the engine and in the car. I'm leaving pulling the head as a last resort.

Thread repair options: I've looked around and found that Save-a-thread and Time-sert are the most common. These don't seem like a possibility for me since after you've inserted the new threads; it requires that you swedge it. Problem with this is since this is plug hole #3 (right next to inner fender) I can't swing a hammer. The other option would be an old Heli-coil. I like this option, but they are hard to find these days. I've seen them on eBay. My concern with Heli-coil is the tool to cut new threads is a "T" handle and it's too long. Maybe it can be cut down. I don't know.

Anyhow, chime in if you have any experience with thread repair in the car. Thank you all.

krowbar · Nov 26, 2014

You can use a crescent or open end wrench on the tap for the heli-coil. Just make Damned sure you keep the tap straight with the hole. I've never used one for a spark plug though. I would think you could get blow-by past the threads,unless the plug could still seat to the head properly. My advice would be remove the head and do it right. Maybe contact Edelbrock for their suggestion.

Car Nut · Nov 26, 2014

krowbar said:
My advice would be remove the head and do it right. Maybe contact Edelbrock for their suggestion.

:yes:

super-bee_ski · Nov 26, 2014

Yeah...
Or, if your not comfortable fixing it your self...do as Car nut says...OR take to a Local Machine shop...
Sorry abiout your screw up man...

UPDATE: I just called Edelbrock here in torrance So Cal..
They said:
They do not have "in-house" repair but to send it to a local and credible Machine Shop in your local area.

PS: I looked up the SF area, plenty of machine shops...
Should not cost you more that $100 to fix it (In my opinion)

Sixpaksteve · Nov 26, 2014

"I'm leaving pulling the head as a last resort."

I realize that pulling the head is a P.I.T.A., but my first thought as I read your posting was - how do you ensure that there aren't any aluminum shavings down in the spark plug hole unless the head is off? More than likely you've already put some down the hole as you attempted your earlier repair, and since those shavings are aluminum getting them out with a tiny magnet isn't an option.

I agree with Car Nut & Ski....take the head off and send it to a machine shop or you could wind up with bigger problems internally.

happyjackdaddy54 · Nov 26, 2014

Just ask your how pissed your gonna be when you screw up this head by not doing it the right way. Bite the bullet. Pull it and have a professional fix it

Meep-Meep · Nov 26, 2014

You can get a heli-Coil kit just for spark plug threads. Pack the tap flutes with grease so the chips stay put and take small bites. Back the tap out and clean the flutes periodically so chips don't build up and fall in.

SublimeSixpack · Nov 26, 2014

Yep, bite the bullet, remove the head and do it right, you'll be glad you did!

bm02tj · Nov 26, 2014

I have done motorcycle aluminum heads with the grease trick but I knew where the old thread was
Because you already ran a thread chaser in this hole pull the head unless you can account for all the metal
just my 2 cents

dvw · Nov 26, 2014

Tim-sert. Weld a cup on the end of the peening tool. Hit the end of the modified peening tool with a quick jolt from and air chisel. I've installed plenty of freeze plugs this way at a pretty severe angle in the car in my dealership days.
Doug

krowbar · Nov 26, 2014

dvw said:
Tim-sert. Weld a cup on the end of the peening tool. Hit the end of the modified peening tool with a quick jolt from and air chisel. I've installed plenty of freeze plugs this way at a pretty severe angle in the car in my dealership days.
Doug

What???

lewtot184 · Nov 26, 2014

do it the right way. yank the head and either buy the 14mm heli coil kit or take to an auto machine shop and have it repaired. all the heli coils I've done required drilling.

bm02tj · Nov 26, 2014

The 14 mm helicoil tap is 5 in long total and does not need drilling the first 1/2 inch of the tap is 14mm to be guided by what is left of the old thread then cuts new thread for the coil
you need to make sure to use correct length coil so it locks in

1 MEAN66 · Dec 14, 2014

PULL THE HEAD!!!!!!!! You will be "cutting" in new threads. Where do ya think that the metal (even tiny amount) will be going. Jerry

Input Wanted: Stripped Spark Plug Threads

Detroit Iron

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krowbar

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Car Nut

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super-bee_ski

FBBO Gold Member

Sixpaksteve

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happyjackdaddy54

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Meep-Meep

дворянин

SublimeSixpack

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bm02tj

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dvw

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krowbar

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lewtot184

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bm02tj

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1 MEAN66

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