[DeTomaso] water pump mounting hole repair

[Gray Gregory]

Doug,

 I would definitely drill and tap the insert before I put it in the block. my guess is a 1/4-20 insert probably has 3/8-16 thread and will screw right into your block. you can thread the insert into a 3/8 nut, put it in a drill press vice and drill it out, then thread. I would also just go with a plain old threaded insert for this not any kind of locking type. once you verify it will thread into the block and the 5/16 bolt will thread into it just use lock-tight or even jb weld to hold it. remember we're not talking about a head bolt or anything that requires big torque, it's just a waterpump bolt it just needs to be good and snug.

good luck,

Gray

________________________________
From: Doug Braun [doug at silicondesigns.com]
Sent: Thursday, June 03, 2010 12:44 PM
To: Gray Gregory
Cc: detomaso at realbig.com; jeffrey.g.kimball at boeing.com
Subject: RE: [DeTomaso] water pump mounting hole repair


Thanks Gray,

I had thought about doing something similar like pre-drilling a 1/4" hole in a 3/8-NC-16 bolt, then slicing off a 1/2" of the threaded length, which I'd then screw into the block with J-B weld on the threads.  After it cured, I could then tap it to 5/16-NC-18 and see if it holds.  If this fails I haven't lost anything.  But either this way or yours runs the risk of just turning the insert farther into the block when it's tapped due to the high tapping torque.

What I don't like about the self-locking type of EZ-Lok (McMaster #90259A139) is their very high installation torque and their tendency to cross thread on installation due to their type 2A outer threads .  This would put high stress on the narrow shoulder I have left in the block.

The only other way I can see not to risk the block without drilling out my water pump hole is to suffer loosing a concours point by installing a dual diameter (i.e. welded together 5/16 & 3/8) stud and use a nut (thanks BTW to whoever suggested this).  This is certainly my safest choice.

If I do end up using a 7/16 OD insert, I'll likely use either McMaster #92070A331 or #94165A443 which both feature lower installation torque vs. the self-locking McMaster #90259A139.

Doug

----- Original Message -----
From: Gray Gregory [mailto:rgg at gregorycook.com]
To: doug at silicondesigns.com,JDeRyke at aol.com,detomaso at realbig.com
Sent: Wed, 2 Jun 2010 20:53:15 -0400
Subject: RE: [DeTomaso] water pump mounting hole repair

Doug,

I think you're fine to use the 7/16 od insert but just for fun (and your peace of mind) I would first try modifying a smaller insert. get an insert that will thread into your 3/8 hole and then try drilling and taping that insert for the 5/16 bolt. if it works you'll have a very thin insert so be sure not to over tourqe the bolt. if it doesnt work all your out is an extra threaded insert.

good luck,

Gray

________________________________________
From: detomaso-bounces at realbig.com<https://webmail.ihostexchange.net/owa/?ae=PreFormAction&a=ReplyAll&t=IPM.Note&id=RgAAAABJL%2fFJ0fWLSbmwWZ5%2f7H%2bwBwB5syEKYwp9RY60zTbpgjrtAArkOA5OAAB5syEKYwp9RY60zTbpgjrtABBAmi8aAAAJ#> [detomaso-bounces at realbig.com<https://webmail.ihostexchange.net/owa/?ae=PreFormAction&a=ReplyAll&t=IPM.Note&id=RgAAAABJL%2fFJ0fWLSbmwWZ5%2f7H%2bwBwB5syEKYwp9RY60zTbpgjrtAArkOA5OAAB5syEKYwp9RY60zTbpgjrtABBAmi8aAAAJ#>] On Behalf Of Doug Braun [doug at silicondesigns.com<https://webmail.ihostexchange.net/owa/?ae=PreFormAction&a=ReplyAll&t=IPM.Note&id=RgAAAABJL%2fFJ0fWLSbmwWZ5%2f7H%2bwBwB5syEKYwp9RY60zTbpgjrtAArkOA5OAAB5syEKYwp9RY60zTbpgjrtABBAmi8aAAAJ#>]
Sent: Wednesday, June 02, 2010 1:33 PM
To: JDeRyke at aol.com<https://webmail.ihostexchange.net/owa/?ae=PreFormAction&a=ReplyAll&t=IPM.Note&id=RgAAAABJL%2fFJ0fWLSbmwWZ5%2f7H%2bwBwB5syEKYwp9RY60zTbpgjrtAArkOA5OAAB5syEKYwp9RY60zTbpgjrtABBAmi8aAAAJ#>; detomaso at realbig.com<https://webmail.ihostexchange.net/owa/?ae=PreFormAction&a=ReplyAll&t=IPM.Note&id=RgAAAABJL%2fFJ0fWLSbmwWZ5%2f7H%2bwBwB5syEKYwp9RY60zTbpgjrtAArkOA5OAAB5syEKYwp9RY60zTbpgjrtABBAmi8aAAAJ#>
Subject: Re: [DeTomaso] water pump mounting hole repair

For two reasons

1) Because I don't want to ruin the valuable 1970 original water pump
casting by drilling it's thru hole out to 3/8".

2) The judges check the heads and head markings on the water pump bolts.
These are indented head bolts which if you file down an indented 3/8 head,
the indent will disappear.

Do you think that not enough meat will be present in the casting to support
the threaded-insert?

Doug

-----Original Message-----
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Sent: Wednesday, June 02, 2010 10:25 AM
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Subject: Re: [DeTomaso] water pump mounting hole repair


Doug, since you seem to want to rescue this thing at any cost, why not take
the oversize 3/8" bolt and carefully file its hex down to a 5/16"-size. In
place, no judge will see the bolt threads or shank. Whatever, good luck- J
Deryke