CO and Timing on a Hybrid Engine?

[SeaDweller]

I've read where 3% CO and 35 degrees total advance are good settings on an SC engine, but how about a hybrid set-up? I've got an '83 longblock with a CIS injection assembly from a '78 Euro version engine. Should I work from these settings, or would they differ being that I've got a larger intake system?

Thanks!

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Michael
'78 911SC Euro

[john walker's workshop]

should be the same. you could go 3.7% if it smooths out the idle better. 35° total is usually ok for performance as long as it doesn't ping. did you port the heads?

[This message has been edited by john walker's workshop (edited 10-08-2001).]

[SeaDweller]

Thanks John..........

Unfortunately, I didn't have time to port the heads. The engine was already built and ready to go into the car, which would have meant removing the injection assembly and performing the machine work to have it done. The car is my daily driver, and doing this would have delayed the engine installation by at least a week (plus put me way over budget), so I made the decision to finish the project.

In speaking with my mechanic, he said something to the effect that the '83 heads have a larger port than those found on an '81 or '82 (but not as large as those in a '78), and that there was only a 1mm or so difference in the port size between a '78 and '83 head. He also mentioned that the venturi effect created can be beneficial depending on the tuning.

I plan to install either SSI's or the early style exhaust sometime in the future, so hopefully the lack of porting won't cause too much of a problem. I will not be racing the car, but I do want to make sure it is a smooth running daily driver. I was also informed that the "block" itself is a 930 Turbo block, which evidently has a better oiling system.

In any case, I'll try the tune-up specifications to see how they work out.

Thanks a bunch!

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Michael
'78 911SC Euro

[Superman]

I believe the '78 and '79 have the same heads, and the '82 and '83 have the same heads. the oddball is the '80 head.

Is this correct?

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'83 SC