I moved-'77 911S runs bad after tow
 

Hi,

I just moved back to Michigan from New Mexico (7200ft in elevation to 600ft or so) a few weeks ago.

The 911 is running poorly and I can't figure out why. It's got a 2.7 w/CIS. I towed it back with no problems, except for some rain along the way.

It starts easily but then starts to backfire through the intake (Pop off valve seems to be working nicely). It runs real rough.

Any ideas? Altitude? Rain? I'm having a hard time with this one...

Kris

i thought the backfire in the intake was a sign of a lean mix...
i moved from 100 ft to 5300ft and was a tad bit richer after the move...
i will let someone who knows more take a stab

Yeah, that's what I thought as well. Just turned the mix screw like 1/4 turn but no real change.

If it still has points installed then check timing and point dwell. Then get a gas tester and set the CO (mixture). Jim

It's got the permatex electronic system installed. I'll check timing and break out the gunson.

JW advises 3.5% CO. Let us know what works best for you.

Also, check recent threads on WUR and AAR.

Take off the distributor cap, check all the plug wire connections top and bottom- they could of moved or been jerked/bumped lose. While you have the cap off take the rotor off and with your key scrape the carbon off the brass pick-up tip edge. Inspect for other signs of wear and put the cap back on.

Cost, 10 minutes 0 cents.

Outcome; hope for the best.

Just thought i'd update:

It was running wayyyy lean after hooking up my Gunson (altitude!). Adjusted it to 3.5%, re-checked timing at idle. Now It seems to run great except for when I get on the gas--it seems not to rev very high. When I punch it it gets to about 3500rpm's and then seems to hesitate but not cut out (almost like a rev-limiter kicks in or something).

I'm running electronic points. The only thing I can think of is that I should adjust timing at like 6k instead of at idle?

Thanks