Help!! Issue with my 76 911s

[Virus911s]

I decided to install the pertronix electronic ignition today and rid my points.... but after I installed, I have nothing but issues. First when I fired it up, it was running on what sounded like 4 cyl. checked all wires... all were good... When I bring it to about 3k rpm it runs fine, but has no power under load??? feels like I'm dragging a BMW around... I spend all day trying to figure it out, but no luck.... What are your recommendations on the air/fuel mixture?

timing is a 5* TDC


1976 Porsche 911s
2.7 non carb... bosh injection.

Thank you for your input...

[ClickClickBoom]

Do a search on ignition timing. Read a bunch, it will become clear. The Pertronix just replaces the points and either it works or doesn't.

[ossiblue]

As posted, it's probably a timing issue. Some petronix units require a specific air gap between the pick-up and the magnet. If yours does, be sure it is set correctly. Secondly, if you removed your distributor to install the unit, you may be off one tooth on the install or otherwise off on the timing. Let us know just what you did to install the unit. Is your rotor on securely? Sometimes the magnetic ring is not seated completely and the rotor is not able to seat either. Something to double check. Finally, reinstall your points, gap and time the car and see if it runs correctly. Please let us know the results of your checking.

If everything ran fine before you installed the petronix, don't worry about fuel mixtures. That comes much, much later.

[Virus911s]

All I did was a direct replacement from points to the new unit. I did not remove the whole distributor. I figured it would be good to go, but that's not the case... Thank you for the good info. I will be re adjusting everything in the morning and let you know how it turns out. Everything seemed to install great... where did you install the main 12v wire? I ran mine in to the engine bay fuse box with the ignition wire which only has a current when key it turned on... does this need a constant 12v current? thanks again... ill update in the morning...

[Virus911s]

So looks like I fixed the timing, it was way off... It's now at 6* and seems to run awesome,but...... I still have a constant backfire about every 10 secs.... Constant "pop" "pop"??? Any advise?

[James Brown]

you don't need that wire powered all the time, just with the key on. pop pop pop out the exhaust i take it? might be valves and a ton of other things. go for a drive

[Howard M]

How old are your plug wires? Misfire? Check them out in the dark (look for sparking across wires).

[Virus911s]

Brand new cap, rotor, plugs, wires, electronic ignition.... It only happens when it's warm? When it's cold it runs perfect. Thanks for the help. I read somewhere about a warm up vacuum? Or valve?

[ossiblue]

Originally Posted by Virus911s

Brand new cap, rotor, plugs, wires, electronic ignition.... It only happens when it's warm? When it's cold it runs perfect. Thanks for the help. I read somewhere about a warm up vacuum? Or valve?

Make sure your valves are adjusted correctly then, it's time for fuel pressure checks and air leak checks. You haven't made clear just from where the "pop" is coming. If it's from the intake, you likely have a lean condition that's due to either fuel pressure out of spec or air leaks. If the "pop" is coming from the exhaust, you may have a leak in the exhaust manifold connections. Let us know a bit more about your backfiring, from where it's emanating, and under what conditions you can make it happen.

[Virus911s]

Sorry, should of mentioned that.... It's the exhaust. As soon as it hits operating temperature the pop pop pop flares up.... But the car runs great!?

[Virus911s]

[ossiblue]

Originally Posted by Virus911s

Nice looking car. I guess, from the picture, you live in Austalia?

Before you dive into anything else, be sure your car is timed dynamically, using a timing light and tach. Make sure the advance is smooth and achieves its full range. Once you have the timing confirmed and the valves adjusted, if the problem persists you can begin other avenues of inquiry.

[Virus911s]

Albany Oregon!! Always cold and raining thanks for the help guys, out for a drive

[Virus911s]

So just go back from drive, plenty of power and feels good, but I have a new issue.... When I let of the throttle it will stay at 2000 rpm then drop about 10 secs later or when I put load on motor... It then finally rests at 900 rpm... Should not take 10 secs to drop to idle? Any ideas... And yes the vacuum line on the distributor is connected.... any ideas....

Thank you

[Steve@Rennsport]

Originally Posted by Virus911s

Albany Oregon!! Always cold and raining thanks for the help guys, out for a drive

Looks like its simply stuck to the ceiling and these do not have inverted fuel & oiling systems.

Easy fix, yes??

[Virus911s]

So what's the fix lol?

[Virus911s]

Remove decel valve?

[Howard M]

Sounds like classic vacuum advance weight hangup. My '76 did that too. The distributor is not hard to take apart, clean and lube.

[redstrosekNic]

Originally Posted by Virus911s

Remove decel valve?

Pull the vacuum hose off the top and plug it. See if this allows your engine to return to idle properly.

I just did this to mine yesterday

[Virus911s]

Well that worked amazing!! Think that fixed multiple issues...