My turn, offy weber - HELP!

OK guys, here's my setup. 63 drop top falcon, Rebuilt '68 200, D8 ported head, offy with 34ICT/ICH webers, 800 RPM idle, 3.03 3 spd, 9.2:1, 206@.050/108 rapid lift cam about 2 degrees advanced, DUI at 12 deg (was at 14 but hot starting was difficult on the starter) any farther back to stock and the idle quality really, really suffers and there aren't any vacuum leaks. Now for the "issues". I can't really get it to run very well when I put a load on the engine. It (finally) idles OK with a bit of a lope and has 17in vac. When I take it out on the road, it'll stumble on take off and need a bit of throttle to keep it from stalling. Then when I floor it, it'll again stumble and cough through the carb - not really back fire but more like a strong stumble. Here's how I set up the carbs: Installed each indivdually on the center, set the idle screw and then the idle mixture via the vacuum gauge as high as possible then a 1/4 turn open more. When installed individually I found 60 idle jets to give me the best adjustment (3/4 turn out) with 50s being too small (lots of turns out to make any noticeable change to vaccum) and 70s being too bit (I could close the idle jet completely and it would run rough regardless of screw position). I put my uni-syn gage on the carb to and got a reading and tried to make each the same when they were individually installed. I then installed all 3. Without touching anything, on start up it ran aound 2500RPM. Sooo, I closed each idle screw down the same number of turns until I was around 1300. Then I attempted to use the carb sync gauge to balance them. The only way to make the gauge go up or down was to turn the idle speed screw. Idle jet screws did nothing. The carbs were actually pretty close on the gauge. Next, I closed the outer idle speed screws to completely close the butterfly and had to go up on the center carb idle speed to keep it running. It then ran poorly and rough with vacuum down to 13-14 inches. Turning the idle jet screws closed caused it to smooth and increase vacuum. So I dropped jet sizes to 50 and found 3/4 turn out on all 3 to give me the highest vacuum around 16-17 inches. Once the idle speed screws were closed on the outers, the gauge dropped all the way down and turing the idle jet screws did nothing to the gauge - so I guess the carbs are not balanced. My collection of idle jets are 3 each of: 45, 50, 52(qyt2), 60, 70. I have 2 HW5200's that have 170/190 main/air jets that'll fit the 34s. I know the main jets on the 34s are currently 155 on the outer and 170 on the center. The center air jet is 190 and I don't recall what the outers are. Can anyone give me really basic step by step instructions on balancing - apparently I'm not the sharpest tool in the shed. :roll: Also any thoughts on the stumble? I'm basically finished on a 5 year build and have to get it running so that I can finally register it.

TIA

I have fooled with a lot of single Webers before, and usually a stumbling problem is from it being lean in the main fuel jet. SIXGUN on here has run multiple Webers a lot, maybe you can PM him directly for assistance on getting the in sync.

Ok, I'll look at the jetting. Keep 'em coming...

Could be that your bogging down. Try to lean your main carb down a bit. The outers open as secondaries so make sure that they are blocked off for idle. I'm running the same carbs and I've got mine running pretty smooth.

How do you have your vacuum advance hooked up. remember that the webers don't have an off idle vacuum source so your will need to run full manifold vacuum. Of course this will increase you idle so just simply turn down you idle speed screw. I had my distributor recurved only pulling 7 deg off the vacuum can. So set you initial timing to 10 -12 degrees. hook the vacuum and reset you idle to around 750-800 rpm. If you can smell the gas then your most likely running too rich, mixture screw adjustment at that time.

I'll stand by my opinion that the outer two carbs must have the idle circuits shut down completely-the outers should act as secondaries and should open progressively so that all three are open at WOT. The engine should run on the middle carb only until about half throttle. The bog you are getting is way too much fuel/air too soon in the range where it can't use it. I have tried both ways of setting this up and this is definately the way to go. My car when floored at 20 mph or so will run like a scalded cat and continue to pull until I let off. I have a 65 idle if I recall and I can run my idle down to about 550 if I want. I'm currently changing my throttle linkage from the pedal, but can get some pics if ya want to email me that will show some of the basics.

OK - I've tried just about everything else, so we'll see how it runs with the outers closed on both the idle speed and mixture screws. That means there isn't any need to have the carbs balanced. As long as WOT is set on all three at the same time, then all should be good.

I have not worked with Webers on the TriPower. The '61 Comet 250 currently has Holley 1904's, and had 1100's, Yf's and others - sometimes mixed...
Initially tuned and got road worthy with one 2bbl on adapter after typical unrelated glitches of ignition and cooling systems. Current setup is basically a higher CFM 1904 that ran good with outer carb ports blocked - and then tuned to accept the close to closed - leaky air and dribbling fuel outer lower cfm carbs. Seems not much atomization is happening with outers closed, but vibration and tolerances let the outer 1904's contribute to A/F even when shut. Also the progressive linkage adjustment as Offy describes uses outers with quick snap to WOT past typical cruise position apparently to limit intake vacuum drop at low RPM which can cause bog or backfire. Static tuning in the driveway can be frustrating, under load on road the throttle response may be very different.

Have Fun
Powerband

I'm interested to see how you get yours running smoothly. I just finished building a '68 200 with a 3x1 setup using a lot of tips that pulled from Patrick66, Jahearne, and the Falcon Performance Handbook. It's been quite a project, and now I'm just to the point of getting everything dialed in. Any tips and pictures you have would be greatly appreciated.

Closing the outer mixing jets (and idle speed screw) helped in my set up. I think I need stronger return springs to keep the outers closed so that vacuum isn't pulling them open. It looks like I'm on the way to getting it dialed in.

Thanks for all your help.

I installed springs on the outers to keep them shut under conditions that would otherwise force them open and it is noticable.

vssman":1zf2nvhg said:

Closing the outer mixing jets (and idle speed screw) helped in my set up. I think I need stronger return springs to keep the outers closed so that vacuum isn't pulling them open. It looks like I'm on the way to getting it dialed in.

Thanks for all your help.

Click to expand...

I needed helper return springs as well on the Holley carb setup. The Offy linkage includes linkage hairsprings to use on the Holleys but they weren't sufficient to ensure consistent idle. It takes a little more pedal effort but works.


Powerband

Throttle linkages like to stick a bit. make sure that they re aligned throughtout there throw. maybe a small washer spacer to make sure that all the pulls are in line. helped with my set up..

I also use a "dry" lube that is used on bicycle chains to keep everything nice and free.

I finally got it running pretty good. Here's how I have it set up.

Idle on all 3 with #45 idle jets and have all 3 sync'd. Running 147 main jets with a 195 air correction in the center and 170s on the outers. 16 degrees advance connected to the center carb ported outlet.

Thanks for all of the advice...