Tuning issues.. Jake can you advise?, advance curve or jetting (that is the question) |
|
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. |
|
Tuning issues.. Jake can you advise?, advance curve or jetting (that is the question) |
brant |
Jun 9 2009, 12:52 AM
Post
#1
|
914 Wizard Group: Members Posts: 11,641 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
I finally got my latest project running but not well enough
I need to do a little tuning... its a 1.7 motor with a cam (don't know the specs of the cam) from the previous owner I can get leak down/compression, but don't have them at this moment. I also don't know the compression, but it is mild... probably stock the P.O. claims it was rebuilt and I believe it I took all of the tin/push rod tubes off, and it looks to have been rebuilt with out worn/shot stock cam lobes and with lifters showing no significant wear doesn't seem to burn-smoke or leak any oil at this point. Its running 40mm dual webers, currently testing at 3300 foot altitude (motor came from a running car at about 5500 ft) I rebuilt the carbs and the jetting is: -28mm (chokes) main venturis -2ndary venturis 4.5 -main jets 115 -air jets 200 -emulsions F11 -acc. pump ball jet 50 -acc. pump towers 50 -idles 50 I've never carbed a 1.7 before The motor came with a 009 distributor and points I ditched it and put in a L-jet 914 (1.8) distributor with points, blue coil, and no retard/advance lines hooked up the cap/rotor/plugs/wires are all good-new car idles smooth, pulls fine from standing, and then stumbles mildly from 2000 - 3000 the car clears out and runs great at 3000 or 3100rpm timing is currently set at 29degree's, but this is my norm for altitude. dad and I are in disagreement about the cause he thinks its too rich for the tiny motor I think its a distributor curve issue Jake, do you know? I have a Djet distributor available easily... or could put the 009 back on... or think maybe I should buy an 050 somewhere to see if the curve is actually the problem We discussed buying 110 mains also to play with it... thanks in advance for any advice from the guru's out there brant Attached thumbnail(s) |
HarveyH |
Jun 12 2009, 08:00 AM
Post
#2
|
Member Group: Members Posts: 450 Joined: 19-June 03 From: Downingtown, PA Member No.: 843 |
About 14 years ago when I first got my car, 2056, 009 Dist, cam and dual 40 IDF's, I was very dissatisfied with the low and mid range running, particularly around the transition points. I did some calling around to Weber suppliers for recommendations on jetting, and they all recommended that i significantly upgrade the ignition before trying to rejet. Put in a Pertronics and that helped (Yeah, I know about Pertronix failures now, but mine has run for about 14 years). Second step a couple of months later was a Crane HI-6 multi spark, again a noticeable improvement. After a bit more reading up I did a little work swapping jets, one set at a time so you know what is really happening, and got some improvement. As the internet came along and I was able to get more information, I decided to swap the original distributor back in (the PO had given me that with some parts), again, more improvement. Last change was to run a vac line from the tap on one carb barrel to the advance pot of the distributor, again, some improvement. I'm still running the 28mm venturies that came in the setup, but I got a set of 32's at Hershey, so sometime I'll put those in and maybe have to chase the jets around again.
My experience FWIW. Harvey |
ME733 |
Jun 12 2009, 09:21 AM
Post
#3
|
Senior Member Group: Members Posts: 842 Joined: 25-June 08 From: Atlanta Ga. Member No.: 9,209 Region Association: South East States |
About 14 years ago when I first got my car, 2056, 009 Dist, cam and dual 40 IDF's, I was very dissatisfied with the low and mid range running, particularly around the transition points. I did some calling around to Weber suppliers for recommendations on jetting, and they all recommended that i significantly upgrade the ignition before trying to rejet. Put in a Pertronics and that helped (Yeah, I know about Pertronix failures now, but mine has run for about 14 years). Second step a couple of months later was a Crane HI-6 multi spark, again a noticeable improvement. After a bit more reading up I did a little work swapping jets, one set at a time so you know what is really happening, and got some improvement. As the internet came along and I was able to get more information, I decided to swap the original distributor back in (the PO had given me that with some parts), again, more improvement. Last change was to run a vac line from the tap on one carb barrel to the advance pot of the distributor, again, some improvement. I'm still running the 28mm venturies that came in the setup, but I got a set of 32's at Hershey, so sometime I'll put those in and maybe have to chase the jets around again. My experience FWIW. Harvey |
Lo-Fi Version | Time is now: 12th June 2024 - 12:56 AM |
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 ... |