New carbs- one barrel pulling in too much air |
|
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. |
|
New carbs- one barrel pulling in too much air |
tornik550 |
Jul 1 2013, 07:45 PM
Post
#1
|
Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
I purchased brand new weber 44 idf carbs from redline weber recently. I set everything equally between all barrels. I set the idle stop at 1/2 turn on both carbs. The engine started right up. I disconnected the linkage. Checked the air flow with a snail. Equal readings on cyl 1,2. Cyl 3 was pulling in so much air it was off the chart and cyl 4 was barely getting any air. I backed off the idle stop completely and I am still getting a huge amount of air in cyl 3 and almost none in cyl 4.
I took the carb off and visually inspected. Everything appears normal. Both butterflies appear closed. FYI- I am certain that this is not a valve or cylinder problem. Everything was fine with my previous setup. Any ideas? |
Mike Bellis |
Jul 1 2013, 08:12 PM
Post
#2
|
Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None |
Temporarily swap the carbs right & left. If the problem is still on #3, the valve train is suspect.
|
brant |
Jul 1 2013, 08:16 PM
Post
#3
|
914 Wizard Group: Members Posts: 11,623 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
there is a balance adjustment screw between barrels on the webers.
|
tornik550 |
Jul 1 2013, 08:20 PM
Post
#4
|
Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
|
tornik550 |
Jul 1 2013, 08:22 PM
Post
#5
|
Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
|
Dr Evil |
Jul 1 2013, 08:28 PM
Post
#6
|
Send me your transmission! Group: Members Posts: 22,995 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region |
Dang, Steve. You have a fecal touch with carbs.
|
McMark |
Jul 1 2013, 08:38 PM
Post
#7
|
914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
Not the first time I've seen new webers with throttle butterfly problems. If you pull that carb off, and hold it up to the light, I bet you'll see a HUGE gap between the throttle plate and the bore.
You can try loosening the screws that lock the plate to the throttle shaft and see if you can get them to sit better. |
tornik550 |
Jul 1 2013, 09:23 PM
Post
#8
|
Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
|
ThePaintedMan |
Jul 1 2013, 09:38 PM
Post
#9
|
Advanced Member Group: Members Posts: 3,886 Joined: 6-September 11 From: St. Petersburg, FL Member No.: 13,527 Region Association: South East States |
Not the first time I've seen new webers with throttle butterfly problems. If you pull that carb off, and hold it up to the light, I bet you'll see a HUGE gap between the throttle plate and the bore. You can try loosening the screws that lock the plate to the throttle shaft and see if you can get them to sit better. (IMG:style_emoticons/default/agree.gif) That's exactly what it sounds like. One is aligned, and the other is not. |
rhodyguy |
Jul 2 2013, 06:45 AM
Post
#10
|
Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,080 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
by balance adj you mean air bypass screws right? did you try closing all of them? there is no reason for the plates to be misaligned. mblizzard had issues with his brand spankin' new carbs. redline. send them back. or screw around with them for a month or so and they might work. or not.
k |
ThePaintedMan |
Jul 2 2013, 07:37 AM
Post
#11
|
Advanced Member Group: Members Posts: 3,886 Joined: 6-September 11 From: St. Petersburg, FL Member No.: 13,527 Region Association: South East States |
by balance adj you mean air bypass screws right? did you try closing all of them? there is no reason for the plates to be misaligned. mblizzard had issues with his brand spankin' new carbs. redline. send them back. or screw around with them for a month or so and they might work. or not. k I agree again. Didn't think of that. Make sure all 4 bypass screws (the ones furthest to the outsides of the carbs) are completely closed before doing anything else. |
McMark |
Jul 2 2013, 08:45 AM
Post
#12
|
914 Freak! Group: Retired Admin Posts: 20,179 Joined: 13-March 03 From: Grand Rapids, MI Member No.: 419 Region Association: None |
QUOTE there is no reason for the plates to be misaligned. Bad manufacturing seems to be a very good reason. |
Mblizzard |
Jul 2 2013, 09:14 AM
Post
#13
|
Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
I bet you got the set that I sent back to Redline! They never would work for me. Check the floats and see if they are stained or flaking off small pieces of the float. If they are send them back because there was something wrong with those carbs that I just could not make work. I tried a huge number of suggestions from Redline and the members here and the carbs just would not work! If Weber and or Redline is sending out carbs that you have to fix their manufacturing flaws is that something you really want to do?
By the time I was done, I wished I had just purchased a known used set. I had another $250 in jets and Venturi's and a whole lot of time invested before I sent them back. Regardless of what Redline says, 36mm Venturi's are too large in the 44s for our engines. When I went to 28s on the second set they began to work well. PM me if you want the details of my experience. |
yeahmag |
Jul 2 2013, 10:34 AM
Post
#14
|
Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
This isn't necessarily abnormal. Close all the bleed screws and find the cylinder pulling the most air. Bring all the other barrels up to it then finalize your balancing left and right. This is a bit of an art, but really a 2 banana job.
Note: Everything else - especially valves need to be perfect before you do this. You should only need to do this once. |
rhodyguy |
Jul 2 2013, 11:24 AM
Post
#15
|
Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,080 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
that is NOT a good nor a rational reason mark. (IMG:style_emoticons/default/wink.gif) jake quit selling NEW webers for a good reason. (IMG:style_emoticons/default/smile.gif)
|
rhodyguy |
Jul 2 2013, 11:38 AM
Post
#16
|
Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,080 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
to add to my post. closing all of the by-pass screws and measuring the flow on each throat helps you find a baseline. you then have to bring the highest ones down to the lowest. not to exceed the max # of turns out (by passing the venturi) specified in thomlinson's weber manual.
|
yeahmag |
Jul 2 2013, 12:05 PM
Post
#17
|
Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
It's just the opposite. With all the bleed screws closed you have to bring all the barrels up to the highest one.
|
tornik550 |
Jul 2 2013, 12:17 PM
Post
#18
|
Senior Member Group: Members Posts: 1,248 Joined: 29-January 07 From: Ohio Member No.: 7,486 Region Association: None |
It's just the opposite. With all the bleed screws closed you have to bring all the barrels up to the highest one. One of the problems is that I cannot reduce the amount of air flow in the highest cylinder even if I back off the idle set screw. If I bring up the other cylinders o match the highest cylinder, I would idle at around 2000. |
yeahmag |
Jul 2 2013, 12:23 PM
Post
#19
|
Advanced Member Group: Members Posts: 2,421 Joined: 18-April 05 From: Pasadena, CA Member No.: 3,946 Region Association: Southern California |
Now that... Is a problem. That sounds like a bad throttle plate or bent shaft. If these are new you need to work to return them. If not you can either examine the problem and fix it yourself (it's really not rocket science) or send them to Blackline (they bought ACE):
http://www.thesamba.com/vw/classifieds/detail.php?id=1453210 |
ThePaintedMan |
Jul 2 2013, 12:27 PM
Post
#20
|
Advanced Member Group: Members Posts: 3,886 Joined: 6-September 11 From: St. Petersburg, FL Member No.: 13,527 Region Association: South East States |
One of the problems is that I cannot reduce the amount of air flow in the highest cylinder even if I back off the idle set screw. If I bring up the other cylinders o match the highest cylinder, I would idle at around 2000. So you've already verified that they're all closed (gently bottomed out)? I think Mike (Blizzard's) scenario is really likely. You might have gotten his messed up set. 1) Verify all air BYPASS screws are bottomed 2) See if it makes a difference. If not -> 3) Pull the carb off again 4) Use McMark's flashlight in the bores trick to make sure both butterflies close correctly. If not, back off the throttle shaft screws and realign them. 5) If still problems, send them back to Redline as Mblizzard did. |
Lo-Fi Version | Time is now: 15th May 2024 - 04:50 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 ... |