Crank to Cam dimension on 616 engine.

[Jacques Lefriant]

Hi Brad
Thanks Brad the marketing department is evaluating the options. I think Ibraham's cover should be configured to accept standard oil pumps. A pump spacer could be supplied if the punp drive was not to be altered so you could use the cam repair piece.
j

[Albert Tiedemann]

This way because the Cam coupling has tight fit to oil pump shaft ,we can even use the corner damaged oil pump shafts with out any problem
this way we do not need to make 5mm short oil pump shafts and do more parts and expense...
IK

I do not think that the cam coupling[Swiss Army industrial engines only per Brad] has a tight fit in the cam slot. This could introduce a parallel shift in the cam center-line by one's ability or not to locate the cam coupling exactly on the camshaft's axial axis. At the very best, you "hit it right on center" and preserve what you started with. The coupling appears to have a very close fit to the oil pump tang--and since the slot is machined perpendicular to the cam gear interfacing tongue-- this clearance may not be enough to assemble the third piece without binding the parts. Better to let the coupling piece float and play the part of a faux oldham coupling center. If you decide to reuse the oil pump shaft with the worn tang with the industrial engine connective piece, you may have enough length remaining to work with the connective piece by just cutting the worn part off. "Just cutting the worn length off" is a bit misleading because the tang has been heat treated and may require wire EDM removal or machining by grinding. Water jet machining may also be an option.

Jan:

Please ascertain that the coupling piece pictured slides in both the cam slot and over the oil pump driveR gear tang.

[Jan Balder]

Ab,

Engine was assembled half a year ago.

From memory, no accurate numbers but "feel" :

The connecting piece had about 0,2 mm. play in the camshaft slot and the oilpump drive tang had about 0,1 mm. play in the connecting piece.

The connecting piece had to be "glued" into the camshaft slot with heavy grease or it would drop while assembling the third case piece.

Jan.

[Ibrahim Kuzu]

[quote="Jan Balder"]Ab,
The connecting piece had about 0,2 mm. play in the camshaft slot and the oilpump drive tang had about 0,1 mm. play in the connecting piece.

Jan,
Thank you for the info.
I think every one here likes this free play much more than .70 mm crazy gap ( pounding on the oil pump shaft corners )

Ab,
Great points ,however it looks like if we EDM or grind 5mm from oil pump shaft ,there will be not much left to grab the coupling in healthy way....
And I checked the 5mm increase on casting oil pump housing, this also causes shift on the sheet metal etc.. it disrupts crank pulley w/ regular pulley ( on our 4" Carrera pulley not that much a problem but we are making the new timing cover multi use, got to consider all )

So I think we may have to make 5mm short oil pump shafts as factory did and supply with the coupling,
Also ,I think it is good to and may be factory did same, make different sizes of the coupling like cam gear, plus and minus and Zero
to accommodate the differences on the CL's thru the cases that new timing cover will be installed....

Brad,
Thank you...

Jacques,
Yes you are right ,we are doing standard oil pumps. But we are not making oil pump gears... Existing oil pump gears will be used ..
IK

[Larry Coreth]

Ibrahim,

Could you rephrase and/or explain what you mean here? I totally confused.

I think every one here likes this free play much more than .70 mm crazy gap ( pounding on the oil pump shaft corners )

[Ibrahim Kuzu]

Larry,
Sorry about that...What can I say weak English on this side of the poor guy

As you know The gap( distance ) on the cam slot to oil pump shaft tang is .70mm please see the picture

Jan verified that the industrial engine cam coupling Cam side is .20mm gap ( that is .50mm less )
and oil pump tang side to coupling slot is .10mm
These are much better clearances than what we have in our existing engines w/out the Cam coupling.
IK

[Dennis ODonnell]

"( pounding on the oil pump shaft corners )"

Gee, Larry. Seemed pretty clear to me.

roughneck.png (156.55 KiB) Viewed 1238 times

[Jacques Lefriant]

Ibraham
if you don't machine the #4 brg in the third piece installed on the case you are going to have to install it by centering the cover on the crank then you could tailor the oil pump slot to fit after you align the cover as best you can. In the early days i believe the 3 pieces were finish machined as a unit. by the time they got to the 912s then they had it together and did not have to keep all three pieces together. This might explain why the tolerances are tighter on the industrial fix and why it was not offered earlier.
j

[Larry Coreth]

Ibrahim,

OK, I get it now, the side tab to slot clearance. Yes I always thought Porsche got a little carried away there


Dennis,
Your imagination is more fertile than mine !

Having been an engineer for many decades and dealt both with people technically astute and those less so I have had to learn to parse my words carefully. Also in my early days as a young and eager engineer my bosses constantly drilled in to my head, "be precise and brief". This was particularly critical in the days when I was dealing with a German affiliate in Germany and I had to be "precise and brief" in German ! No mean task !

So Ibrahim, I appreciate your dilemma and encourage you not to take offense when you are not understood immediately but learn the precise vocabulary.

[Albert Tiedemann]

Ab,
The connecting piece had about 0,2 mm. play in the camshaft slot and the oilpump drive tang had about 0,1 mm. play in the connecting piece.


Ab,
Great points ,however it looks like if we EDM or grind 5mm from oil pump shaft ,there will be not much left to grab the coupling in healthy way....

So I think we may have to make 5mm short oil pump shafts as factory did and supply with the coupling,
Also ,I think it is good to and may be factory did same, make different sizes of the coupling like cam gear, plus and minus and Zero
to accommodate the differences on the CL's thru the cases that new timing cover will be installed....

IK

"Healthy way". Maximum engagement would be on the order of the actual thickness of the disc portion of the coupler because the end of the tang would bottom out on the tongue portion of the coupler. Just making a new shaft 5mm shorter and providing a flat distance on the tang .5mm greater than the thickness of the disc portion of the connective piece does not necessarily satisfy a healthy engagement as you have not changed any engagement of connective parts. If the connective piece is heat treated[likely], the engagement could be reduced and viewed as "non healthy" and you may be able to save the oil pump gear shaft. The clearances on both the tongue and slot can be minimized as long as a sliding action is ascertained.* The geometry of the connective piece will take up all machining errors that you are currently wrestling with as long as the sliding action is preserved and that the slot travel is in excess of the distance between the misaligned axes of the oil pump driveR gear and the camshaft. Tangs are ground to the drawing specified thickness and the oil pump slot width is a function of the cutter width that is used to sink a groove into the end of the camshaft. From a design standpoint [and good engineering practice], the width of the slot and the thickness of the tang would have been dimensions under "control" and may[should] have even been called out as critical as this would affect the sampling plan for Quality control inspections. Ah, the beauty of having the actual design drawing--should one ever surface instead of making SWAGS at what actually is conveyed thereon! When you are making gabillions of camshafts like VW was, it is not any more expensive to make a cutting tool if not standard to any practical width. The cutter dimensions that would affect the design values intended would be[should be] specified on the drawing.

* No real need to have selective assembly of this special connective part[ made especially for the Swiss Army industrial engines]. Just "glue" it in place with heavy grease to hold it from falling when the third piece is fit as Jan suggested; besides, making a small quantity of those connective pieces will be expensive. Economies could be realized if a CNC mill/ turn machine were used and a quantity produced to satisfy such a manufacturing method. On small quantities, the basement advocate with manual equipment and one specialized accessory and maybe making a holding fixture or two for creating the arc on the connective piece
should be able to make one in about a day or so. Add about 2 weeks for heat treating turn around and attendant additional expense--unless you make it from a material that can be heat treated in a kiln and removed for air cooling.

So, if someone makes "a few" and asks $75-100 for them, don't be too alarmed.

[Brad Ripley]

I recall we sold about 200 pcs of those oil pump couplings. Remember, those engines were mainly for aircraft ground power units running at a fairly constant rpm. The coupling was certainly an idea to cut down on wear and maybe noise. The stock end tang drive was good enough in thousands and thousands of VW and Porsche engines.

[Jacques Lefriant]

Hi Ab Stoddard was able to sell 200 pcs since they had a new gear and shaft and were less expensive than the std new gear and shaft. the big bonus was you didn't have to fix/replace the cam. Replacing the shaft only did not address gear wear or housing wear and could be disastrous if the required press fit was not maintained since most did not have a key way. I am always surprised by the mind set of the community. Yes for your edification you can make beautiful one offs and charge a lot for them. That piece in qty say 500 should be $10 or less retail. But even if they are free you still have to redo the shaft and you have not addressed the gear. And even a new gear does not restore the pump unless you are using a new/better third piece.
j
BTW in instances like this rather than doing it your way give the part to a good CNC Job Shop since the programing and fixturing costs are about the same as your manual setup and the incremental cost for the subsequent pieces is minimal.
j

[Norm Miller]

I wonder what happens to the adapter doohickey if you remove the oil pump drive gear?
Does it fall into the crankcase/third piece?
Ouch!

Norm

[Jan Balder]

With the "doohickey" ( ) in place in the camshaft slot, it has only 0,2 mm. axial play between the camshaft and the aluminium boss inside the 3rd piece for the oilpump shaft so it cannot come out of the camshaft slot after removing the drive gear.

Jan.

[Ibrahim Kuzu]

Working on the final touches of the casting model.
Like to thank every one who has given valuable info.

Jan,
That .20mm between oil pump shaft casting boss and the Cam coupling surface is quite close....I sure like to see that around .40 mm
or .50mm
For this may be good to remove some material from the boss casting before timing cover installation w/ use of cam coupling in the engines...

May be it is time to get back to Crank center to Cam center dimension and I still wonder what was the factory call
95.50mm or 95.750 mm???? and the tolerances...??

As Gary said, the one of the last replacement cases will give us good info ....But As Jacques and others mentioned
many cases out there with different CL.
So,best is we leave some material on the crank and cam bore to machine them with the existing engine case for the perfect CL..
IK