Can someone help me identify this threaded hole on my engine block?

[Papa]

I was looking for a good place the run a ground strap and saw this threaded opening in my engine. Any idea what it's intended to be used for and if this would make for a good location to attach a grounding strap? I'm not certain, but it may be NPT and not machine threads.

https://farm5.staticflickr.com/4734/27406163349_0125f49dc1_b.jpg (https://flic.kr/p/HKMKxK)

[Big Blocker]

Older cars used to mount the transmission cooler lines on a bracket in that hole . . . we're talking old C4, C6 tranny's. Should be another one farther up toward the front.
It's a solid place to ground as long as the hole is already threaded for you - do NOT drill it deeper, crankcase on the other side. Be careful of too long a bolt. Threads should be course thread, not NPT.

Doc

[OVCobra]

It is the drain for the water jacket, yes it is a pipe thread. Must be plugged or can add a drain-**** to ease coolant drainage.

[Jeff Kleiner]

Well, that would ordinarily be a block drain (which indeed would be NPT) that goes through to the water jacket. Not sure why yours doesn't seem to go through??? Nonetheless your photo shows an ideal place to attach a ground strap---under that engine mount bolt :)

Jeff

[Big Blocker]

Water jacket doesn't go that far down . . .

Doc

Papa, I'm 01 of those 10

[TexasAviator]

I think you are all wrong lol. That is a bolt for a strap that holds the wire loom from the starter around to the front of the engine where the wire is then sent up to the starter solenoid. There is another one closer to the front as well. The best ground bolt in my opinion is the one holding the starter to the block.

[Yama-Bro]

I'll have to check back on old posts to be sure, but I think someone else asked about that hole awhile ago. If I remember correctly, I looked into it and discovered it was used for mounting or bracketry for a larger starter. I'll see if I can find that post.

[Papa]

Well, that would ordinarily be a block drain (which indeed would be NPT) that goes through to the water jacket. Not sure why yours doesn't seem to go through??? Nonetheless your photo shows an ideal place to attach a ground strap---under that engine mount bolt :)

Jeff


I'll have to check back on old posts to be sure, but I think someone else asked about that hole awhile ago. If I remember correctly, I looked into it and discovered it was used for mounting or bracketry for a larger starter. I'll see if I can find that post.

Yama-Bro: Don't spent too much time looking for that thread. I'm going to follow Jeff's advice on this and attach the ground strap to the engine mount bolt. Sometimes it's the simplest solution that is the hardest to see.

Thanks,
Dave

[Yama-Bro]

I'll have to check back on old posts to be sure, but I think someone else asked about that hole awhile ago. If I remember correctly, I looked into it and discovered it was used for mounting or bracketry for a larger starter. I'll see if I can find that post.

I found the old post... see it here (http://thefactoryfiveforum.com/showthread.php?25198-BluePrint-347-in-and-secure!-Quick-question-on-hole-near-the-starter). I did remember correctly, to sum it up: some starters have a bracket that utilize that hole, however it's not used in most cases. The hole is 7/16-14 threads (not NPT) and is roughly 1.50" deep. No need to plug it. You can use it for your ground strap if you want.

[Papa]

I found the old post... see it here (http://thefactoryfiveforum.com/showthread.php?25198-BluePrint-347-in-and-secure!-Quick-question-on-hole-near-the-starter). I did remember correctly, to sum it up: some starters have a bracket that utilize that hole, however it's not used in most cases. The hole is 7/16-14 threads (not NPT) and is roughly 1.50" deep. No need to plug it. You can use it for your ground strap if you want.

Cool! Good to know what it is.

Thanks,
Dave

[Yama-Bro]

Yama-Bro: Don't spent too much time looking for that thread. I'm going to follow Jeff's advice on this and attach the ground strap to the engine mount bolt. Sometimes it's the simplest solution that is the hardest to see.

Thanks,
Dave

No problem. ;) I have a feeling this question may come up again, so we've got complete answers now for future searchers.

[kgkeys]

Mine definitely holds the bracket for my stock AOD cooler lines.
-Kyle

78006

[Yama-Bro]

Mine definitely holds the bracket for my stock AOD cooler lines.
-Kyle

78006

Yep, it sure is. I'm guessing it's probably had several uses over the years.

[Jeff Kleiner]

Well, that's the last time I'll drink a glass of Kool-Aid that Go-Dad-Go gives me (however....if he wants to offer me a Sazerac or Creole Bloody Mary I'm all in ;) ). It's small block Chevys that have a drain plug in that approximate location:

https://www.corvetteforum.com/forums/attachments/c3-tech-performance/48155532d1501528106-anyone-not-recommend-using-engine-block-drain-plugs-to-flush-coolant-2007mods0024.jpg

Cheers,
Jeff

[Higgybulin]

There's a freeze plug in that hole, it's not threaded. The motor mount suggestion is a good one.

[Papa]

There's a freeze plug in that hole, it's not threaded. The motor mount suggestion is a good one.

Sorry, I should have annotated my photo. The hole in the red circle is the one we're discussing.

https://farm5.staticflickr.com/4733/39199135871_224510ca32_b.jpg (https://flic.kr/p/22HTPqc)

[Higgybulin]

Lol, yes me to! Looks like there's a plug in that one as well, or a heli coil.

[Papa]

Lol, yes me to! Looks like there's a plug in that one as well, or a heli coil.

It definitely has threads, so a helicoil is likely.