Help: Clearancing 7R case for 930 oil pump...template?
 

I neglected to get my case clearanced by Ollie's for my oil pump. I am handy with a grinder and while I am content doing the clearancing by trial and error, I am curious if anyone either:

Has a claranced case open to draw a cardboard template of the clearanced case web.

OR

Already has a template to share.

Thanks.

HI kenikh
you just need to make the No'3 main the same profile as the No'2 main as the photo;

http://forums.pelicanparts.com/uploa...1264149706.jpg

to clear the oil pump case and clearance round the pump, 964 pump in a 7R case;


http://forums.pelicanparts.com/uploa...1264149815.jpg

please do not use a grinder on the mag case, a linisher/belt sander or a diegrinder with a corse cutter, as I have found hard bits in the casting and have been told the Mag'will set on fire easly, it has been known.

regards mike

great education here!

Great pics and explanation. Thanks, Mike.

Can you clarify what meant around the tools to use/not use? I was planning on using an air powered die grinder with an extremely coarse, spiral cutter and some machining coolant in a spray bottle to keep things cool and to keep bits from flying around.

Good/Bad? I don't have easy access to a mill...

I would ship the case back to Ollies and have it done right. The shipping and additional machine work is really not that much compared to messing up the case or setting this thing ablaze (although that bit is new information for me, love the knowledge on this board).

Bill

For most, I'd agree with you, but I am a more than competent machinist.

I have been out of practice for 13 years, but there was a time when I spent 4 hours a day, jumping between a Bridgeport mill, 12' engine lathe, various EDMs, Haas and Mazak CNCs, etc. building specialized machine tools and parts.

I know what I am doing. :)

Do not be afraid of using a die grinder and coarse carbide bit to shape magnesium parts. I've wielded them up and reshape parts without any issues. I would just cover the case to only expose the area you are working on. Just like open heart surgery. This will prevent any bits from getting in to the oil passages.

Take your time and use machinist bluing to help keep focused on the material you want to remove. spin the bit fast enough to eliminate tool chatter. You do not need to much force or tool speed. Let the tool do the work!

Save your money for somthig else like 3.6 piston squirters

HI kenikh
tools ahould be OK, should take you about 20min to sort, di-grinder and cutter like this?

http://forums.pelicanparts.com/uploa...1264257216.jpg

and a small linisher to finish off,


http://forums.pelicanparts.com/uploa...1264257263.jpg

just watch out for the hard bits, some times in the casting, not alway's, but some times.

regards mike

Kenik

I did this on my 930 case. I wasn't smart enough to notice that I could just match the other web, so in some places I just kept grinding until I had a fit. I used something - can't remember if it was a cut-off wheel or a saw to make the main cut on the thick web, then used the die grinder to finish it off with some contour.

If a guy like me can do it, someone like you with genuine machining skills should have no issues.

I have, or had, some bits of mag case from a tranny which was converted to a jig. I certainly did not set any fires with my Sawzall cutting that case. I should set the torch on one of the bits to see if I can get it to burn. I know powdered magnesium can burn in the atmosphere, and recall reading of a magnesium engine or something in a race car burning after some other disaster put enough heat in the wrong place. Aren't our cases a magnesium/aluminum alloy, maybe less susceptible, though maybe a bit heavier, than a purer magnesium?

But mag 911 cases are machined all the time, so there must either be little danger here (especially if the cuttings are promptly removed?), or simple ways to deal with it. One doesn't hear of our 911 mag bits acting like flares. And even when a 2.7 blows up, you don't hear of the case burning.

Walt

HI Walt
I am not saying that his case will set on fire, it is just to take care and keep a eye out for any sparks from the cutter, as some cases on the odd occasion have hard bits in and have set fire to the shavings, I have cut/linished/ used a diegrinder and had no prob's, my brother on the other occasion has un-knowingly set fire to his legs with a spark from the cases when hand finishing some 7R cases for a race car, just to take care when at home.

regards mike

Kenik, Ollies did mine, you can see how much in a couple photos here:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/379187-assembling-1966-901-05-engine-phase-i-bottom-end.html