Carb Timing Question, Backfiring... |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Carb Timing Question, Backfiring... |
yarin |
May 18 2005, 05:09 PM
Post
#1
|
'14-X'in FOOL Group: Members Posts: 988 Joined: 13-May 03 From: Guttenberg, NJ Member No.: 693 Region Association: North East States |
I'm trying to work on the timing on my car. I bought a Sears Induction Advance timing light and i'm going based on Pelican's tech articles. Basically the car backfires like crazy over 3k rpm at any decent load. I hooked up the light, i think i see the major 34deg mark on the fan.. is this the wide fan blade? Do I set the timing light to 27 degrees at 3k rpm and line up the large fan blade with the mark on the housing?
Anyhow, i changed the timing around a bit and it still backfires like crazy out the exhaust. It also huffs on the intake side here and there. I don't have any electronics to set the dwell. This problem came up after two autocrosses. Any ideas? Fresh plugs, cap, rotor and wires already done. This is my first time really getting into carbs so pardon my ignorance but I can't seem to find the "vacuum advance line"? Where would it come from and where should it connect to? Thanks! |
Jake Raby |
May 19 2005, 09:08 AM
Post
#2
|
Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
The big issue with carbs is that you need more initial (idle and low speed) advance than with EFI. This means that at idle you are probably at 6-7 degrees to attin 27 degrees at full advance with the stock dizzy.
Ultimately with carbs I choose a setting of 12-13 degrees at idle to better burn the less atomized fuel from the carbs and then retain the 27 degrees at full advance. This can be done with a stock distributor, but not easily. This is where the Mallory Unilite shines and I sell them already set up and optimized for your Type IV engine application. The Mallory uses an optical trigger as a pick up instead of magnets, or points to do the job. |
Lo-Fi Version | Time is now: 9th June 2024 - 07:39 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |