Author Topic: 302 oil sending hole thread  (Read 3050 times)

fireZ

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302 oil sending hole thread
« on: August 04, 2008, 10:50:58 PM »
Anyone know what the thread is were the oil sending unit threads into on a 302 engine? I am trying to clean the thread up before installing the sending unit. Thanks
1968 Z28 LA Built
LIC # RPO Z28

CNorton

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Re: 302 oil sending hole thread
« Reply #1 on: August 05, 2008, 12:56:51 AM »
1/8th pipe.

fireZ

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Re: 302 oil sending hole thread
« Reply #2 on: August 05, 2008, 12:01:31 PM »
Thanks for the help but I think the owner previous me has run a 3/8 NF 24 down through the hole. Will a heli-coil fix this do you think?
1968 Z28 LA Built
LIC # RPO Z28

JohnZ

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Re: 302 oil sending hole thread
« Reply #3 on: August 05, 2008, 02:38:54 PM »
Thanks for the help but I think the owner previous me has run a 3/8 NF 24 down through the hole. Will a heli-coil fix this do you think?

I'm not aware of a Heli-Coil that will adapt a straight machine thread to a tapered NPT thread, and there isn't much difference in the diameter of a 3/8" machine thread vs. a 1/8" NPT thread to make a typical bushing - not enough wall. You'll probably have to make a custom adapter fitting with a hole through it with 3/8"-24 male threads that screw into the block (and a square shoulder with a gasket to seal it) with a larger top section that has 1/8" NPT female threads to accept the stock adapter fitting. Maybe Jerry has seen this kind of butchery before and has another suggestion.
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fireZ

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Re: 302 oil sending hole thread
« Reply #4 on: August 05, 2008, 02:49:44 PM »
Thanks John, I am very discouraged by what a so called machinist did to my block. I am going to talk to some other machine shops and see if I can get a adapter made to take care of this problem. I guess a matching 68 Z28 motor means nothing to some ,just another motor.
1968 Z28 LA Built
LIC # RPO Z28

CNorton

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Re: 302 oil sending hole thread
« Reply #5 on: August 05, 2008, 03:46:41 PM »
There's a "mistake" that's a little more egregious than most.  Anyone who can't feel the difference between chasing a 1/8" pipe thread and cutting threads with a 3/8" machine tap may have made other mistakes as well.  Even the greenest apprentice should have noticed that something wasn't right with the situation.  It makes one wonder.

fireZ

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Re: 302 oil sending hole thread
« Reply #6 on: August 05, 2008, 04:07:32 PM »
I agree with you this guy had to know he was cutting material away. He contends it was already that way when he recieved the block. I am sick about the situation.
1968 Z28 LA Built
LIC # RPO Z28

JohnKY

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Re: 302 oil sending hole thread
« Reply #7 on: August 05, 2008, 04:33:36 PM »
Can you drill it out, and re-tap with 1/4" NPT? Then, use a 1/4 X 1/8 bushing.

fireZ

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Re: 302 oil sending hole thread
« Reply #8 on: August 05, 2008, 05:04:22 PM »
Yes I think it will have to be drilled out and then basically sleeved before it is retapped
1968 Z28 LA Built
LIC # RPO Z28

fireZ

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Re: 302 oil sending hole thread
« Reply #9 on: August 07, 2008, 05:32:48 PM »
I tried what John Z mentioned and it worked perfectly. It took a little work  to make the bushing with a male thread but in the end it worked. Another 68 Z motor saved for the original car, Thanks everyone
1968 Z28 LA Built
LIC # RPO Z28