[b-man]

Does anyone manufacture one of these plates in 1/2” thick steel with a 1/2 NPT tapped hole in the center?

Rather than make my own I’m wondering of this piece is offered by the Tri-Power specialists for those not running vacuum linkage. It’s the perfect spot to mount a water temperature gauge.

The block off plate I have pictured is only .110” thick, I’m thinking something around .500” thick would allow enough 1/2 NPT thread depth to seal the fitting.

[steve25]

How much bigger is that hole then 1/2 pipe?
Do you have enough foward clearance to tap it for a 3/4 to 1/2 pipe bushing?
I know a 3/4” pipe tap is not cheap these days if you do not already have one. But doing such would save you from tracking down a small scrap of 1/2” steel or aluminum and then craving the block off plate out.

Another way would be if you can weld then much thinner steel plate could be used and welded to a steel pipe fitting.

[steve25]

If that hole is less then .921” in diameter then to tap it for 3/4” nPT you will need to drill it with a 59/64” drill bit, which once again you might have to order up and likely not cheap.

You will need a two handle drill to power that size bit also!

[Stuart]

This is something I've thought about for decades but never acted on. I could use one too. Welding or brazing a 1/2" NPT fitting into a flat bit of steel should also work, although you'd have to make sure it doesn't warp from the welding heat.

I don't know the diameter of the hole in the manifold offhand but it's fairly large, and it would be best to use an adapter plate rather than modifying the manifold.

[steve25]

Something like one of these 2 kits from Moroso might work for you if you can get the measurement for the bolt spacing.

[pfilean]

I wanted both a mechanical gauge and the original light working so I just drilled and tapped the blank off plate used a little teflon tape and put the sender in. Been there for years with no problem. I know that plate looks a little thin for pipe thread, but it works.

[GtoFM]

This flange was on a ‘64 389 I got 50 yrs ago. It was bolted to the LH head over the rear freeze plug.

It is 0.250” thick and tapped 1/2” NPT. Not sure how the PO used it on the rear of the LH head. Maybe a sensor or tried something for better coolant flow.

Clearance to firewall is about 3 1/2”. It would less conspicuous back there if there is enough space.

Optional location would be RH head front if no a/c or alt. there.

The key will be finding the correct bolt pattern. It’s a flange for a hydronic heating pimp. Ck local plumbing/heating supply houses or HVAC contractors.