DanMan

Ok these nice shiny gauges are killing me just sitting here. I installed the boost gauge last night and boy did that go slick!
Now, time for the pyro, and this is what's been delaying the install. I got ISSPRO gauges from DieselManor and on their site and on the invoice it says to use a size "R"(.338") bit for my 1/8" NPT probe. However, the TST instructions say to use a 5/16" bit for it, which would be just a tad smaller. Now if the 5/16" will work just fine then this thing is gonna get done tomorrow. Will it work and tap fine with 5/16"?

Bob Wagner

grease it up either work fine.

MikeThomas

5/16 will work fine, Cast iron is really easy to tap because it self lubricates due to its metallurgy. The grease on the tap is to catch the shavings, or you can just pull the turbo to be on the safe side.

Teddy Bear

Yeah we used a 5/16 one on mine. It was a little tight but it worked out good. I think it calls for a 21/64 but thats a pretty odd size. The 5/16 should work just fine.

Boatnik

21/64 is closer to "R" than 5/16". However, in cast iron you will be OK using the 5/16. When I drilled mine I started the truck and used the back pressure of the exhaust to blow the shavings out while drilling and tapping. It wouldn't hurt a thing to stuff a couple rags in the tail pipe to generate a little more pressure. I still greased the tap just to be safe.

DanMan

I'm thinking of either taping the exhaust and using the running method or just dropping the turbo, granted the nuts will loosen OK.

DanMan

I found these instructions on PDR's site that say to use an 11/32 bit, and that sounds about right. It's 1/32" bigger than 5/16".

http://www.piersdiesel.com/TechPyroInstall.htm

bgilbert

I think you'll find that Isspro egt probes are 1/4npt. Much bigger hole than 1/8npt. There is a bushing available from Isspro for about $8, this way you can drill the hole for 1/8npt and use the bushing. You won't need to go buy bigger drill bits and if you mess up above 1/8npt, there's no going back. If you mess up drilling for 1/8npt, you can always go up to 1/4npt.

tomd

Did you all use a 7/16th tap? (7/16 NF20)

edwinsmith

One more size for ya! I have the tap I used on mine and it says to use 21/64 drill.

Edwin