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70's Opeler, back 4 more!
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Discussion Starter · #1 ·
Keith (or anyone else with similar connections),

What did you do to tap your valve cover for the connectors? Did you use anything like a JB Weld compound?

I've got to plug my back hole due to F.I. and am looking to put a 5/8 inch Brass L.P. Plug in it. The problem with the 5/8" plug is the threads are as large as the actual plug. So, I'm looking to turn it down to fit and was wondering about threading it or using some kind of epoxy/weld compound.

Thanks!
 

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Usually the rear (large) hole is tapped for 1/2" NPT (pipe thread) and the small hole is tapped 1/8" NPT. Those pipe plugs are pretty easy to find. I've also seen the rear hole plugged with a "frost plug" for the EFI set-up.

I like to use hose-mending type nipples, with the barbs on both sides. They can fit up much closer to the valve cover. I cut all but the last barb off the one side going into the valve cover, tap it into place, then throw the whole thing in the oven. I set the broiler to it's highest setting and when the manifol is good and HOT, I solder the nipples into place with plumbing solder. You might recognize this trick from the fuel fitting on the Solex carb, it works there too.

No wonder my marrage didn't work, huh?
 

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70's Opeler, back 4 more!
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398 Posts
Discussion Starter · #3 ·
LOL!

I did that oven thing way back before I got married in my mom's oven. I was a Yamaha mechanic back in the late 70's and the latest thing was "Perme-Slick."

It was a spray on Teflon coating for engines. You warmed up your pistons, cam, bearings, and on motorcycles, the cylinders to about 400 degrees, along with what ever else you wanted. Then you sprayed on this coating and then baked it again for another period of time to help it adhere. TALK ABOUT Smelling the house up. I don't think my wife would even let me in the house with any of that, let alone use it on a cookie sheet in the oven.

btw. That treatment took my idle from 1000 to 1500. I had to reduce the idle and it gave the bike more pep. I didn't coat the crank or the mains.

(And my wife wonders why my mom is the way she is...):cool:
 

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oh yeah!

I remembered another trick that works just as well, but might be easier if you don't have the taps laying around:

Use a metal valve stem, wheel and tire type, not cylinder head type. The one you're looking for is the kind that motorcycles use and some cars, where the stem is like a golf tee with a nut that screws on from the bottom. It will fit in the small hole, or the large one if you get the truck one, and is pretty easy, cheap, and relativly permanant.
 

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As Stephen said, 1/2 inch NPT for the big hole, 1/8 inch NPT for the small hole. Taps and fittings were easy to find, but I had to drill the small hole a bit deeper into the valve cover to get enough threads. Make sure that you remove the cover plates inside the valve cover and clean it out thoroughly before you put it back on the engine.

I also took the opportunity to replace the old de-mister pads with some new material. I just used brass kitchen scrub pads, but a friend has some stainless mesh pad that I plan on cutting to size and installing.

HTH
 

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Picked up the 1/2" brass fitting today but when I looked at the 1/8" fitting, the holes in it where micro-sized. They were much much smaller than the photo at the start of this thread. Are you sure it's 1/8" for the smaller of the two holes?
 

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1/8 inch NPT Tap for the Small Valve Cover Hole

That's the size of the tap, but you can buy fittings in a number of barb sizes. I think that mine is still 1/8 inch NPT (National Pipe Thread) with a 1/8 inch hose barb, but maybe it is a bit bigger. But it really only has to be somewhat bigger than the PCV orifice, which is 1/16 inch. I think the standard hose is 1/8 inch internal diameter. HTH
 

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Thanks Keith, but maybe I didn't explain well enough. The guy at the hardware store handed me a fitting that was for a 1/8" hose but the actual hole running thru the fitting was 'pin-sized'. (Look at the picture in the first post of this thread, imagine the hole in the smaller fitting being so small you'd almost need a magnifying glass to see it, that's what he handed me.)

Find it hard to believe but the guy at the store (maybe he was new) claimed that was a standard 1/8" barbed fitting. It appeared to me that there was plenty of radius left between the actual hole and the OD of the barbed end.

Hope this helps explain it better.
 

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I guess I wasn't clear. The threaded end of the fitting I used was definitely 1/8 inch NPT. The barbed end can come in whatever size you want (to a limit). I looked at mine, and the inner hole is about 1/8 inch in diameter, while the barb is about 3/16 inch in outside diameter. HTH
 
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