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Model 20 oil capacity


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Hi All,


In between outings with the Hup Model 20  (only displays with minimal driving so far), I have been investigating the propensity of the car to throw so much oil out of the front of the crankcase so readily.  While I understand that these cars have a tendency to do this, mine seems to take things to the extreme! 


I took the camshaft plate / cover off the side of the crankcase to see what actual oil levels I had at the top of the petcock tubes.  This was an interesting exercise that I should have done earlier.  I found that the top of the petcock tubes were quite high in relation to the throw of the crankshaft and I suspect that the big ends were dragging through quite a bit of oil contributing to my problem and also probably causing some drag on the crankshaft as it made it's way through the oil bath.


The other interesting thing I discovered is that the capacity of the front crankcase compartment is much smaller than the rear crankcase compartment. ie. adding the same quantity in each will not result in the same level. The rear compartment has extra space under the crankshaft output.


I dropped the level of my petcock tubes by adding spacers where they screw into the bottom of the crankcase.  This is an easy way of adjusting the height of the tubes inside the crankcase without making any irreversible cuts.  I then jacked the car up as high as I could (to simulate going uphill) and checked to make sure the big ends would still scoop oil.


In case any one is interested, I have included some photos. In one you can see the void under the camshaft drive gear which results in more oil being required in the rear compartment.


Any thoughts or comments certainly appreciated.











Edited by 1912Minerva (see edit history)
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I see you haven't gotten a response, Andrew. I believe the manual says the tubes are 3/4" high. Not sure why yours are longer. You can just cut them to size. I think others have installed seals to prevent oil release out the front bearing. This must have been a problem from the start, as Hupmobile installed a sheet metal cover to keep oil off the hood. I thought of attaching some of that "pig mat" absorbent cloth under this cover.



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Yes, I believe 3/4 inch is correct.  You want the bottom of the connecting rods hitting the oil.  The "drip" system is only to replenish the lost oil.  My bearings are in good shape but it throws some oil too, as Phil says, there was a sheet metal cover over the flywheel, and then it dripped from there to a belly pan....

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Thanks Phil, David and Ken,


I need to drop the top of my petcock tube a bit more to get exactly 3/4 inch.  Looking at the diagram Ken, the top of the petcock tube is exactly in line with where the top of the oil scoop (bottom of big end) would be at the bottom of the stroke. It is interesting that the end of the big end bolt and nut "blocks" the oil scoop.  When putting my motor together we thought about that and worried that the bolt would form a "groove" in the oil and the immediately following oil scoop may be running in that groove and not picking up enough oil.  So we reversed the big end bolts so the oil scoop has clear access to the oil.  Probably worrying about nothing.


Cheers, Andrew.

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  • 5 weeks later...

G,day Huppers Andrew if you still have the cam  plate off  pour in 500cc of oil into each end and note where it rises to on the stand pipes.   We have found that standpipes higher than 5/8 inch rise promote the exterior oiling system. Some earlier production engines were not machined for rod clearance so presume that they just took a bit more oil  By the way your conrods are a different pattern to those in our engines. There are a series of small stamped trade marks on each piece to identify who supplied them. Max Burke Nulkaba 2325 Australia

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