woody3882

I was pulling the plugs today and found the previous owner stripped the #7 plug hole.
This brings me to two more questions, We all know that it is an impossibility to heli-core a spark plug hole with the head on the car (LT-1)

1) is it possible or is there any way to fix the hole thread without removing the head,
using a heli-coil is prohibited because of the tight fit.

2) Because of this and several other problems, If it come to replacing the motor, (after all other attempts to fix it have failed) what would the best choice for a current crate motor that is reasonably priced and would fit my 94 vette LT-1 I have heard that the electronics must be compatible because of the C-4 ECM, What can I expect to pay for a crate motor, and installation costs, I am just preparing for the sticker shock.

Thanks

confab

Can you pull the manifold? Cut the tap down maybe?

confab

I am admittedly unfamiliar with the LT1 cylinder head, but we helicoil aluminum castings here daily. I mean, it happens A LOT.

The taps here aren't plug taps. But looking at them, half the tap is shank. You can whack that with a zizz wheel and grind flats on it in a pinch.

I've turned them with everything.

I have created starting tools from bolts with a dremel cutter slice in the end.

As long as it is reasonably straight, and you get the insert bottomed, helicoils are completely free form. You don't have to have it on the bench. You do have to be careful.

IMVHO.

89dd

http://content://downloads/all_downloads/2899
This guy saved the day on my 89. #7 plug

Siveck

A back tap does wonders for cross threaded spark plug holes. It sound like yours is beyond cross threaded though.

woody3882

I ordered a thread cleaner bit, if that doesn't work (I doubt it will) then I have also ordered the insert set as shown. I don't think I will be able to set the insert with the setting tool but hopefully I can get a new thread cut and then put the insert on the spark plug, then put both in the hole and snug it down tight enough to hold permanantly. I intend on blowing out the cylinder after cutting, did you have much of a problem with the cuttings going into the hole. i can not see into the bore so I will just give it my best.
Thanks I am grateful and need all the help I can get.
Woody

Cliff Harris

The usual method is to load up the tap with plenty of grease to catch the metal chips. Go slow and clean the tap often.

JimLentz

Great idea! I would also think if you can magnetize the tap that would help too.

woody3882

Thanks for the advise JimLentz, but the LT-1 block is Aluminum, (non-magnetic)

JimLentz

Doh, good point, I better go get some caffeine.

RUU

​​​​​​​I assume you mean "head".