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| Cyl Head Oil drain down improvemnts https://www.ausmini.com/forums/viewtopic.php?f=5&t=91216 |
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| Author: | 69cooper [ Sun Dec 06, 2015 10:36 pm ] |
| Post subject: | Cyl Head Oil drain down improvemnts |
Hi guys Looking for some thoughts on the best solutions for resolving oil building up in rocker cover during high rev in my race engine. I understand that 1100s block are prone to bad oil drain down. first solution would be to restrict oil flow into rockers , I understand this can be achieved buy fitting a grub screw with small hole drilled in it to rocker post to restrict flow, does anyone have some sizing that has worked in the past. Next option would be to improve the ability of the oil to return to the G/Box via extra drain lines , one article suggested feeding it back via fuel pump oil in casing , Cheers Mal |
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| Author: | miniandmokeworld [ Sun Dec 06, 2015 11:07 pm ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
Mal Yes a you can restrict the oil coming into the rocker gear area, make sure cam bearings have been fitted correctly....also the factory fitted a breather off the timing cover to help these issues you mentioned also. AB |
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| Author: | 36 [ Mon Dec 07, 2015 8:05 am ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
A piece of feeler gauge with a pin hole under the first rocket post will restrict the flow. And easily implemented in the field. Like AB says, cam bearing may not have been offset properly - just restrict the flow and next time you overhaul the engine correct it. |
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| Author: | drmini in aust [ Mon Dec 07, 2015 12:00 pm ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
I put a 12mm OD drain line off the rocker cover down to the drop gear housing. Not that I have a drainback problem. My PCV valve is connected to the rocker cover, it works fine provided it's not directly above a rocker. It's a road car, but has seen 8000 rpm on track days. Some folks drill the pushrod holes bigger for drainage on race motors. 
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| Author: | TheMiniMan [ Mon Dec 07, 2015 4:52 pm ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
Yes similar too what the good Doc says, we fit a drain pipe from either end of the rocker cover,,, low on the cover like the Doc has we take the drivers side one down to the breather-spot on the primary case with a "Y" piece half way down allowing breathing to a catch can & the passengers side drain (again from low on the rocker cover) down to the fuel pump hole in the back of the block & again with a "Y" piece half way down to the breather catch can it ends up looking like it has 2x handles either end of the engine but works a treat even with Stews fire breathing 1600cc Arden cross-flow mini engine with 145 hp i have done things this way for the past 30 odd years with all our 1415cc & 1510cc stroker engines & not one issue easy-peasy |
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| Author: | FNQ [ Fri Dec 11, 2015 5:29 pm ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
We need to get a little minion in there to work out the volume. I think Mal was after a measurement something like put the grub screw in the feed up to the pedestal and and put a 1/16th hole in it( what size is a pin hole ( to reduce volume ) (Mal this is just an example i have NO IDEA so do not use this measure) . You would think with the lifter bores and holes in the lifters it should escape? but not at full revs |
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| Author: | drmini in aust [ Fri Dec 11, 2015 9:26 pm ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
I've never had a problem with the top end getting too much oil, but I do make sure the front cam bearing is the right way round. If not, you can get a full flow feed, not just an oil pulse once every cam rotation as is normal. [I get GR to fit my cam bearings...] |
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| Author: | Alexw [ Sat Dec 12, 2015 8:23 am ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
Is there a guide or a picture for the installation of the cam bearings? All the manuals I have don't go into specifics for how they should be oriented or installed. Thanks |
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| Author: | 69cooper [ Sat Dec 12, 2015 8:59 am ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
I have check bearing installation and it is correct, I think my problems are being caused by excessive oil pressure , currently it is running at 85 hot , I have installed a shorter spring and it now runs 75 cold, which I can adjust if necessary . Another issue that may be contributing , is the MED heavy duty pushrods I am using, they are have a much bigger dia which restrict return flow. I am wondering how the Nb guys manage return flow @7500 rpm, none if the cars over in WA run a return line form the rocker cover A couple of images of cam bearing installations, slot aligned with gallery to crank bearing, small hole aligned with gallery to top of block  
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| Author: | drmini in aust [ Sat Dec 12, 2015 9:14 am ] |
| Post subject: | Re: Cyl Head Oil drain down improvemnts |
The oval hole in the bush faces the main bearing housing (oil entry). Hard to see in your pic. |
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