Hi
Have been around this endless loop of trying to set the ignition timing on my 74 2.7CIS many times without much confidence.
No longer believe that idle should be 5degrees ATDC.
Wondering if current fuel changes things?
My car runs much better with timing more advanced and I can’t push it back beyond 0degrees ie TDC without poor running.
Worried about having the timing too advanced.
Also if timing is out then idle screw makes no difference and idle is low. Is this just me or do others experience this?
Any experts on setting the timing on CIS cars?
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63sven
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Strictly
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Re: Any experts on setting the timing on CIS cars?
Hi yes, i know this one quite well. Your vaccum line on your dizzy is a retard....5 ATDC or 0 TDC, take your vac off PLUG IT, time it to 35 deg @ 5000 rpm (or 38 @ 6000 if you can manage it, 35@5000 is close enough), then just let the timing at idle fall back to wherever it will wants, this will account for wear in the dizzy, normally around 5 to 10 BTDC with the vac plugged (the vac hose plugged)...you can use this procedure for more or less any 911 engine up to 80's with a vac retard....vw's exactly the same....the retard was for emissions...nice but i recycle and i only drive my 911 once a week, i want to enjoy that.
Now reset your idle on the bypass, and drive. Leave it like for a week or two, check your temps, and notice the starting. It should start much better, then if you want go back and decide between the two. I currently have a 74, but have also done loads of work on 73 to 76 CIS with the throttle position regulator and non vac WUR
....p.s.....even the humble glovebox manual tells your timing is 35 to 38 @ 6000, so as long as you dont go over that you are absolutely fine!! But if you are really worried keep an eye on your oil temps, over advanced timing, would make the engine run 5 to 10 degrees hotter, if everything is normal...pick the best for your car....
p.p.s the air by pass screw by the throttle should work just fine....if not....you have a vac leak...
Now reset your idle on the bypass, and drive. Leave it like for a week or two, check your temps, and notice the starting. It should start much better, then if you want go back and decide between the two. I currently have a 74, but have also done loads of work on 73 to 76 CIS with the throttle position regulator and non vac WUR
....p.s.....even the humble glovebox manual tells your timing is 35 to 38 @ 6000, so as long as you dont go over that you are absolutely fine!! But if you are really worried keep an eye on your oil temps, over advanced timing, would make the engine run 5 to 10 degrees hotter, if everything is normal...pick the best for your car....
p.p.s the air by pass screw by the throttle should work just fine....if not....you have a vac leak...
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63sven
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Re: Any experts on setting the timing on CIS cars?
Many thanks Strictly. Will have another look this W/e.
Strange about the vacuum leak being responsible for the idle screw not being functional.
I have recently replaced every seal on the intake system including injector seals etc and yet nothing has really improved. At idle vacuum is very weak and this doesn’t seem to make much difference if attached or not. Wondering if I have a leak in the intake box itself?
Strange about the vacuum leak being responsible for the idle screw not being functional.
I have recently replaced every seal on the intake system including injector seals etc and yet nothing has really improved. At idle vacuum is very weak and this doesn’t seem to make much difference if attached or not. Wondering if I have a leak in the intake box itself?
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Strictly
- DDK slapper chatter
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- Joined: Mon Jan 07, 2008 4:08 pm
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Re: Any experts on setting the timing on CIS cars?
best way to check is to smoke test. Have a mate who vapes, pull an injector out put a pipe between your mate and the injector hole and watch where the vape comes out....
your throttle body could also be set incorrectly. Run through the measurements for setting the throttlebody and microswitch which you use for starting the car via the hand lever between the seats, it is all in the Porsche workshop manuals.
you will need to be able to adjust the idle using the bypass. Try this as an easy check....pull the vacuum retard of the dizzy, plug the hose...the idle should go up immediatly to around 1500rpm, as your timing is now 5 to 10 BTDC. Simply try and adjust the idle from here....if you simply cannot, then something is definatly going on with your injecttion either an air leak, or an issue with the throttle set up and you will have to find it.
You can download the PORSCHE factory manuals, from the OTHER TECHNICAL SECTION of the impact bumpers forum...great forum, and fantastic resourse....i would not work on the injection without the manuals....
your throttle body could also be set incorrectly. Run through the measurements for setting the throttlebody and microswitch which you use for starting the car via the hand lever between the seats, it is all in the Porsche workshop manuals.
you will need to be able to adjust the idle using the bypass. Try this as an easy check....pull the vacuum retard of the dizzy, plug the hose...the idle should go up immediatly to around 1500rpm, as your timing is now 5 to 10 BTDC. Simply try and adjust the idle from here....if you simply cannot, then something is definatly going on with your injecttion either an air leak, or an issue with the throttle set up and you will have to find it.
You can download the PORSCHE factory manuals, from the OTHER TECHNICAL SECTION of the impact bumpers forum...great forum, and fantastic resourse....i would not work on the injection without the manuals....