Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 911 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered
 
Join Date: Feb 2015
Location: Salinas, CA
Posts: 86
POP and smoke while setting ignition timing

Finishing up a head stud and leak repair on my 1980 911sc. I installed the distributor with cyl #1 at TDC, and I tried my best to line up the rotor with the notch on the distributor, but I noticed that no matter how many times I pulled it out and pushed the distributor back in, the rotor would end up cocked a few degrees away from the notch. I figured no big deal, I'll sort it out with the timing light when I start the engine up.

The engine fired up fine and ran fairly well, though I could see with my timing light that even with with the distributor rotated all the way counterclockwise and the end of the slot butted up against the mounting stud, the timing was slightly retarded I think (the 5 mark was at about 11 o'clock). I consulted with a mechanic friend of mine, who (unless I misunderstood him) told me to pull the distributor out, rotate the rotor a few degrees clockwise, and reinstall the distributor. So I did that.

Then, when I turned the key, it started cranking, started to fire up, and then I heard a very loud POP sound. I took the key out of the ignition, went back to look and I saw smoke rising up from somewhere underneath the airbox - I couldn't tell exactly where but it seemed like it was probably on the left side. The amount of smoke coming out dwindled over time, but it continued to smoke for several minutes.

I'm a total newbie when it comes to diagnosing issues - does anyone know what happened? What should my next step be?

Old 11-24-2019, 04:41 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered
 
Join Date: May 2006
Location: Snohomish, WA
Posts: 1,699
Garage
Quote:
no matter how many times I pulled it out and pushed the distributor back in, the rotor would end up cocked a few degrees away from the notch
When you pull the distributor out, you have to turn the rotor before pushing the distributor back in or you haven't changed anything.

Get the engine back to TDC with cyl #1 on the firing stroke. Then get the rotor lined up with the notch and with the timing adjustment in the middle of its rotation slot.

Quote:
does anyone know what happened?
By turning the distributor clockwise (they spin counterclockwise in 1980), you advanced the timing. If you also left the timing slot butted up against the mounting stud, then you may have been way advanced. The plug fires when the intake is still open and you get a pop and smoke out of the intake.

Do you have a pop off valve under the air filter to protect the air box from this?
__________________
Rex
1975 911s and 2012 Range Rover Sport HSE
1995 BMW R1100RS, 1948 Harley FL

Last edited by Walter_Middie; 11-24-2019 at 06:09 PM..
Old 11-24-2019, 06:06 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered
 
Join Date: Mar 2002
Location: Philadelphia, PA
Posts: 12,607
Garage
Ignition timing..........

Quote:
Originally Posted by targasc1980 View Post
Finishing up a head stud and leak repair on my 1980 911sc. I installed the distributor with cyl #1 at TDC, and I tried my best to line up the rotor with the notch on the distributor, but I noticed that no matter how many times I pulled it out and pushed the distributor back in, the rotor would end up cocked a few degrees away from the notch. I figured no big deal, I'll sort it out with the timing light when I start the engine up.

The engine fired up fine and ran fairly well, though I could see with my timing light that even with with the distributor rotated all the way counterclockwise and the end of the slot butted up against the mounting stud, the timing was slightly retarded I think (the 5 mark was at about 11 o'clock). I consulted with a mechanic friend of mine, who (unless I misunderstood him) told me to pull the distributor out, rotate the rotor a few degrees clockwise, and reinstall the distributor. So I did that.

Then, when I turned the key, it started cranking, started to fire up, and then I heard a very loud POP sound. I took the key out of the ignition, went back to look and I saw smoke rising up from somewhere underneath the airbox - I couldn't tell exactly where but it seemed like it was probably on the left side. The amount of smoke coming out dwindled over time, but it continued to smoke for several minutes.

I'm a total newbie when it comes to diagnosing issues - does anyone know what happened? What should my next step be?


TargaSC,

Let’s hope the backfire did not crack the airbox. BTW, I am in Carmel, CA just several miles from you. If you need some assistance, PM me your number and I will call you back.

Tony

Old 11-24-2019, 07:32 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Reply


 


All times are GMT -8. The time now is 03:05 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.