Yeah hole saws are not the most accurate of drilling devices esp. if you have the kind that use dowels in the mandrel to keep it from locking on.
I would take a compass and mark the diam., drill it a little under then grind to your line.
A Foersner bit gets you the cleanest hole in wood- They aint cheap & I don't know how well one might work for alum.

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<img src="http://farm4.static.flickr.com/3173/2992308402_5481afb26e_t.jpg">

Thanks, Dan!

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Chuck and the Flying Valiant

They make 1 3/8" and also 1 1/2" hole saws. I"ll probably get both. If the 1 1/2" cuts a hair smaller then its label that would be good, otherwise I'll use the 1 3/8" one with a file/grinder/burr.

Then again if they cut on the big side the 1 3/8" one will probably do fine on its own without any work. From what I've seen holes/cuts on aluminum tend to be bigger since the blades have more of a tearing action on soft objects instead of a cutting, widening the kerf.

Pierre,

Yeh, I hate that tearing action. Let us know how the 1 3/8 comes out. When I was using carbide burrs a while back to do aluminum, I posted in a thread that by using PAM kitchen pan spray, I was able to shape and port for 4 hours straight with no grabbing of a burr or any aluminum clogging my double cut burr. Wouldn't cost much to give er a squirt inside the valve cover.

rock
'64d100

I bought a rigid brand 1 3/8", 1 1/2", hole saw and an arbor.

They cut big. Problem is, the drill bit does not fit 100% true in the arbor, its a bit at an angle. When you drill, the whole thing wobbles slightly. Even if it were not wobbling, I have a feeling it would still cut big.

Tip for anyone using the hole saw approach - buy the shorter hole saws, or buy an arbor with a longer bit. This will let you push the bit further back into the arbor so its supported on the very back end of it as well so it sits more true.

After the 1 3/8" saw, and cleaning the hole with a file, it ended up at 1.44" diameter. With the grommet at 1.5", I figured this was acceptable, giving a more secure fit.

The next problem was getting the grommet in the hole - it was not made for such thick material. After some fussing with a flathead, I was able to get it in there. The inner/bottom lip sits at a very slight angle, but it does come out past the bottom of the cover. I was able to get the breather/baffle in and out a few times without the grommet coming off. Once the baffle is seated, its difficult to turn - appears it will seal well.

with the Offy Valve covers, anyone using the Mr Gasket
1) 2060 oil fill cap ? 4.98 at Advance Auto
2) 2054 breather / PCV tube cap with grommet? 7.97 at Advance Auto

both of these are chrome plated, the 2954 may be an alternative to the AC Delco set up that SSD is showing.

thanks

What kind of PCV valve are you planning on using with that #2054? Wrong-diameter tube coming off it, with no provisions for insertion of a PCV valve into the cap itself, would probably make for a kludged-together hose/valve setup. About the only clean way to do this would be to attach a Chrysler #4315 704 breather-to-PCV-valve formed elbow hose to the breather, then an ordinary PCV valve goes in the elbow hose, then plain hose from the valve to the fitting on the base of the carb.

It'd work, but I still like the AC setup better.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks, yes I agree the 2054 would need a inline hose PCV valve,,for a PCV , but as the motor that I am putting this on, (83) has a breather routed to the air cleaner, and a PCV valve separate from the breather, that seems to be what I need to duplicate. I was going to epoxy closed the breather holes in the 2060 oil fill cap, to be as environmentally responsible as possible, unless someone knows of a oil fill cap that seals in this application, then add a breather routed to the air cleaner and separate PCV valve,
the cly head is a 77 to allow the Offy valve cover to work.

Eek, no, you do not epoxy or otherwise block the holes in the breather, otherwise you have no breather!

You can use the AC setup as described originally. The only change you need to make is to use a ducted oil cap/breather on the valve cover's front chimney, such as a Stant 10070. Then connect the hose that runs to the air cleaner to that cap's fitting.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Pierre, Dan and all,

Life intruded a while so it took me to New Year day to fix my Offy. So easy I could scarcely believe it!

I used the recommended grommets...the Dorman 42344 and 42064, and the CarQuest number for the Stant breather cap is 36012. I used a "DoIt Best" 1 3/8 diam hole saw (Number 335603) at $10.35 obtained from a huge home owned hardware store. It took a 1/4" diam centering drill bit that was not supplied with the saw, but those bits are common as dirt.

I drilled a pilot hole, then a 1/4 inch hole, the followed the saw instructions for aluminum and with a 3/8 variable speed drill didn't exceed 390 rpm. I used a long enough bit that it extended past the saw about 3/8 inch and left about 3/4 inch for the drill to grab the bit, not the saw. A 1/4 inch bit is tight in the throat of this particular saw so there was no wobble. I lubed it well with PAM, placed the valve cover on a solid bench, gritted my teeth and did it by hand with the hand drill. Not a single problem!

Finished the edge with a round file, then worked the grommet into the hole. I was able to use a combination of thumb pushing through the gasket hole and finger rolling the lip in the inside of the valve cover to get the grommet lip inside and up on the valve cover surface, then the breather rotated right in.

You couldn't tell it wasn't there from the factory and only took abut 45 mins start to finish.

Thanks for the thinking guys, and Dan, thanks for finding out the parts. nice when sumpin just goes right together.

rock
'64d100