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petercoetzee's Avatar
 
Join Date: Aug 2014
Location: Cape Town, South Africa (if i buy any parts I ship to US address)
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Lets get her running! First start for a first timer.



So its been a few years, and finally at the point where first start will happen. Its been a bumpy road so far;
-Mild steel flanges on Stainless headers replaced with stainless flanges. Odd one that.


-Tank found to be full of rust from restorer, recoated internally and painted


-Carbs to be full of sand (believe it), rebuilt them and set float levels etc correct. Jetting is as per Parrs recommendations. His motor almost identical (Also with PMO 40s).


-Throttle linkages fixed

-Oil breather tank fabricated (hard to find space as the coil packs are mounted on sides next to arches.


-Clutch cable bracket fabricated to lift over throttle cable


-Throttle cable plug fabricated for tunnel as well as mount point


-Correction for square wave from ECU to tech


-Alu velocity stacks fabricated. Previous chrome ones were literally peeling and leaving residue in the carbs.


We have had an aborted first start before. Thank god it was failed as multiple of the above issues would have caused serious trouble internally. The mechanic also had a fantastic way of going about figuring out the polarity on the coil packs. "Try it this way, oh ok that blew the coil pack, other one must be 12v".

Two coil packs and an ECU later, the abuse was done. I have replaced both and checked and traced all myself so the above polarity issues no longer exist.

If I can, Id like to use this thread to ask some noob questions. After the above I have some serious first start anxiety. Thanks in advance to all those that take the time out to help me
Old 12-20-2017, 12:43 AM
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Thermostat oil compensation

So first question, and this one is confusing the hell out of me. The motor has an external cooler. Oil is full, but what happens at first start when the thermostat opens and directs oil to the cooler?

Do I need to compensate for that? Or should I block off the cooler for first start?


Last edited by petercoetzee; 12-20-2017 at 12:52 AM..
Old 12-20-2017, 12:48 AM
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HI petercoetzee

just been looking at your car, looking good,

just a small thing, as you have not driven the car, the clutch cable should go over the top of the throttle link in the top photo and not a strait pull, this will give you a lot of clutch judder and not a lot of control setting off.

hope it helps, unless you have sorted it from posting the photo

regards mike
Old 12-20-2017, 07:16 AM
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Thanks Mike, yes thats why i fabricated the steel bracket so it goes over now. Will send a pic this weekend. I couldnt find the factory one. Cool little side note, the 915 box is off a 73RS that still races FIA events in France. Never could get a hold of the owner.

Any ideas on the oile cooler thing?
Old 12-21-2017, 01:35 AM
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Quote:
Originally Posted by petercoetzee View Post
So first question, and this one is confusing the hell out of me. The motor has an external cooler. Oil is full, but what happens at first start when the thermostat opens and directs oil to the cooler?

Do I need to compensate for that? Or should I block off the cooler for first start?

From what I understand... you'll want to run it long enough for the thermostat to open... at which point the oil will flow to the front where the cooler is and back again.

After awhile (not sure exactly HOW long... some can give you specific time frame)... check the oil while its idling and chances are you'll have to add more oil to compensate.
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Old 12-21-2017, 06:15 AM
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Auxiliary thermostat........

Quote:
Originally Posted by petercoetzee View Post
So first question, and this one is confusing the hell out of me. The motor has an external cooler. Oil is full, but what happens at first start when the thermostat opens and directs oil to the cooler?

Do I need to compensate for that? Or should I block off the cooler for first start?



Peter,

Assuming you have a similar Porsche Factory auxiliary thermostat used in 911 engines, the cold oil from the engine will fill the oil line to the auxiliary cooler and the cooler itself but will not flow through because the thermostat is shut closed at this time. The warm engine oil will be by-passed until oil temperatures approaches 185F. As the oil temp. increases, the slide valve opens up allowing the hot hot to circulate. There is a constant crossectional area of the flow maintained. If a 10% volume flowing directly to the oil tank is diverted to the cooler, a similar volume (crosss-section) is also opened on the other side of the thermostat. In summary, a constant or uniform cross-sectional area of the valve is maintained at any given temp.

Tony
Old 12-21-2017, 09:01 AM
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Originally Posted by boyt911sc View Post
Peter,

Assuming you have a similar Porsche Factory auxiliary thermostat used in 911 engines, the cold oil from the engine will fill the oil line to the auxiliary cooler and the cooler itself but will not flow through because the thermostat is shut closed at this time. The warm engine oil will be by-passed until oil temperatures approaches 185F. As the oil temp. increases, the slide valve opens up allowing the hot hot to circulate. There is a constant crossectional area of the flow maintained. If a 10% volume flowing directly to the oil tank is diverted to the cooler, a similar volume (crosss-section) is also opened on the other side of the thermostat. In summary, a constant or uniform cross-sectional area of the valve is maintained at any given temp.

Tony
Hi Tony

Thank you so much, thats a massive help! Yes it is a Porsche Factory aux thermostat. Wasn't aware thats how it functions, but makes sense as with most things Porsche. Will check pull off the AN fitting to make sure the lines have oil in.

Thanks again
Old 12-21-2017, 10:16 AM
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