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: 11,632 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) |
Jake Raby |
Jun 9 2009, 08:00 PM
Post
#2
|
Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Kick its ass or it'll kick yours..
That said, the set up you have is stock for a 1600cc engine for a Fiat!! Those vents also work great on a 1600cc T1 and your 1700cc TIV.. UNLESS you have a worn cam, shot rings or glazed cylinders or a half ass exhaust.. The VERY FIRST thing that you do when tuning issues occur is verify the engine's integrity with a compression and leak down test- period. With 2.5-3 PSI fuel pressure, float height set at 10& 23mm and the jets you have that engine should run great... The only change I'd make would be running a 220 air at that elevation And remember that 95% of Carburetor issues are actually ignition issues... When I learned about carbs there was no internet, no air fuel meters, I never read a book and no one taught me how the damn thing worked or what the circuits were.. I decided to kick it's ass so I threw changes at it, figured out how they responded to those things and won the battle. That said IF this engine is using an 050 dizzy that IS the fucking problem. Remove it, throw it away and don't look back- they suck, always have and always will and I don't give a damn what people say that have a so called "positive experience" with them.. They are made for WOT running all the time. Most people that "think" the 050 works well have never experienced a properly set up alternative.. They set up retarded at idle and breed hesitations, flat spots and rich running. Carbs are the simplest thing on this planet to work with, nothing is easier to understand on the entire engine IMHO... |
Lo-Fi Version | Time is now: 2nd June 2024 - 01:55 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 ... |