| ausmini https://www.ausmini.com/forums/ |
|
| Weber Tuning Help Required https://www.ausmini.com/forums/viewtopic.php?f=2&t=90828 |
Page 1 of 2 |
| Author: | WasabiPimpNinja [ Mon Oct 19, 2015 8:46 pm ] |
| Post subject: | Weber Tuning Help Required |
Hi Guys, I have recently rebuilt a 45DCOE Weber for my car and am trying to set it up, but having a couple of problems. The car idles nice and smooth at 1.5 turns out from seated, I've got it set to 1000RPM. It free revs nicely through the range with no hesitation when the throttle is slowly opened. Once the car is under load it really stumbles and tries to stall out on low throttle when taking off from the line. Once it gets past that it revs nicely but pops a bit in the mid range. On light to medium throttle once moving it seems to rev well, but sometimes has a stumble on really light throttle. If you load it up full throttle it doesn't pop or carry on. I've tried going half a turn in and out from it's happy setting and it hasn't made any difference to the low throttle stumble. Can any of the Guru's have a look at my settings below and give me any advice? Does it need more timing? Is the emulsion tube correct? Am I an idiot for trying to tune it without the vacuum advance? I can't work out if this is a progression phase or timing issue. Any help would be GREATLY appreciated. Engine: 1098 +40 MILD cam Minor port work New Accuspark Dizzy (Points) Bosch Coil Timing 5* @ 1000RPM, 28* @ 4000RPM Vacuum Advance not hooked up yet (need to install nipple into manifold) Intake: Redline 3005 Manifold Redline Linkage Weber 45DCOE-13 32mm Chokes 4.5 Sec Venturis Idle Jet 40F9 Air Corrector 180 Emulsion Tube F16 Main Jet 140 Pump Jet 45 Float Valve 6.5mm closed, 15mm open Cheers, Keels. |
|
| Author: | drmini in aust [ Mon Oct 19, 2015 9:22 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
F16 emulsion tubes you have in are usually correct on an A series. |
|
| Author: | gtogreen1969 [ Mon Oct 19, 2015 10:07 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
I think the float height should be 7.5mm for the 45DCOE-13. F16 emulsions should be ok for smaller engines - F2 is used on bigger motors. Also try blocking off the pump by-pass jet / bleed back valve in the bottom of the fuel bowl, minis tend to like these closed. Something to do with the way they were designed for 1 cylinder per choke. |
|
| Author: | TheMiniMan [ Tue Oct 20, 2015 6:52 am ] |
| Post subject: | Re: Weber Tuning Help Required |
also probably 3.5 venturies would work better, makes the transition from idle through to main a bit smoother, which is what sounds like your problem is actually |
|
| Author: | WasabiPimpNinja [ Tue Oct 20, 2015 11:48 am ] |
| Post subject: | Re: Weber Tuning Help Required |
Thanks Guys, I'll try and find some other venturis and plug the bleed back valve and see how we go. Cheers, Keels. |
|
| Author: | kath20 [ Wed Oct 21, 2015 8:13 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
Keels. It sounds to lean on the idle jet, the main jet does not come into play until 3/4 throttle up till then you are running on the idle jet, richen it up or go to a larger jet. Cheers . |
|
| Author: | WasabiPimpNinja [ Thu Oct 22, 2015 1:44 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
Hi Kath, I tried richening it up using the mixture screws but it didn't make too much difference. I put in a set of 45F9's and it ran real bad and super rich so figured my idle jetting was ok. On further inspection it appears that the 45F9's I had were actually drilled out by previous owner and were massively oversized... More like 145 jet :O I've got a couple of actual 45F9's and some 50F9's to try as well, and I also picked up some F2 Emulsion tubes. I haven't had a chance to try any of them yet but hopefully that will sort it out. I haven't been able to find any 3.5 Venturis locally yet so I'll play with the jetting first and try the 3.5's when I find some. Cheers, Keels. |
|
| Author: | WasabiPimpNinja [ Mon Oct 26, 2015 1:55 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
Ok, so a bit of an update. I fitted the 45F9 idle jets and didn't notice much difference. There was still a stumble coming off idle and the mixture screws were pretty close to where they were on the 40F9. I then put in the F2 emulsion tubes and noticed the stumble was still there, but felt better. I changed over to 50F9 idle jets and the stumble was all but gone. With the 50F9 the mixture screws are only 1/2 a turn out from seated. I checked the fuel and I think it may have been a bit old or a bad batch, so I put in some fresh 98 octane and that improved it as well, leading me to think a lot of my problems may have been slightly bad fuel. Given this, I may go back to the 45F9 and see how that goes now it has good fuel in it. I took the car for a drive and it felt a lot better. There is still a small cough every now and then when rolling on the throttle from a cruising condition. When loading up the car full throttle in 4th on a gradient at around 50kmph, the car coughs and splutters so I may need to go up a size in the mains as well. When it's up in the rev range it pulls very well and responds nicely. I'm guessing this is due to increased air speed. Is the only way to improve low end air speed by going to a smaller choke? Or will going to the 3.5 venturi help this as well? I have now also hooked up the vacuum advance and found that helped quite a bit in the low end throttle. I think the car could probably do with a little more timing advance so will have a play with that this afternoon hopefully. What do you most people have their maximum advance set at? I still have to pull the bleed valve and block that off, but I'm getting much closer. Cheers, Keels. |
|
| Author: | drmini in aust [ Mon Oct 26, 2015 2:09 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
Most modified 1098s like 30-32deg total advance, all in by 3500rpm. a 9-10 (dizzy)deg advance plate in the dizzy works well. It it's got a 14 or 15, modify it by building the stop up. This mod increases static advance. 10 or 12deg static is good. Not enough advance down low loses torque. |
|
| Author: | WasabiPimpNinja [ Mon Oct 26, 2015 2:14 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
Thanks Doc, I'll check what advance plate is in the dizzy and give it a couple more degrees of timing. Currently it's at about 28deg at 3500rpm. I think my static advance is a bit low as well which isn't helping. Cheers, Keels. |
|
| Author: | WasabiPimpNinja [ Mon Oct 26, 2015 7:34 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
OK, so something is obviously not right with the vac advance set up. I disconnected it and set the timing to 10deg at idle. I plugged the vac advance in and it jumps to 30deg. Bring the revs up to around 3500 and its reading somewhere around 45deg!! The marks are very stable under the strobe and It seems to idle and rev really well though, sounds like it just wants to take off. So what have I done wrong here? Am I supposed to set the 10deg with the vac advance hooked up or is it a case of creating too much vacuum and I should just leave it disconnected?? Or is it actually OK and just giving mad readings because there is no load on the engine? The dizzy is a new Accuspark 49D and I pulled the top out of it to check the markings on the weights/cams but couldn't see anything stamped or marked. <EDIT> OK after reading more about distributors and rereading what Doc said, I think I know what's going on, there's too much mechanical advance in the distributor to get a decent static timing and keep the full advance in check... Cheers, Keels. |
|
| Author: | drmini in aust [ Mon Oct 26, 2015 9:54 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
I would bin vac advance if running a Weber or Dellorto. Too much pressure shock in the ports for stable vacuum. |
|
| Author: | WasabiPimpNinja [ Mon Oct 26, 2015 11:27 pm ] |
| Post subject: | Re: Weber Tuning Help Required |
Thanks again Doc, I'll block it off. Quick sort of related question, in my diggings through the dizzy pile, I found a 45D which has all the right bits in it, but it has what appears to be a simonbbc electronic ignition in it. I vaguely remember having this on an engine a couple of years ago but it stopped working. I remember something about possibly leaving the ignition on and frying the module (or so I thought). Is there anyway to test these modules to see if they are still good? After actually pulling the dizzy apart it looks like the problem may have been the roll pin falling out of the square lobe thing so it wasn't actually spinning with the inner shaft. All things going according should have a correctly set up dizzy tomorrow for more testing. Cheers, Keels. |
|
| Author: | drmini in aust [ Tue Oct 27, 2015 5:24 am ] |
| Post subject: | Re: Weber Tuning Help Required |
Hook it up on the bench with a coil. Put a plug wire & plug into the coil. Hook 12V to it and spin the drive dog clockwise viewed from bottom. Spark @ plug = all good. |
|
| Author: | FNQ [ Tue Oct 27, 2015 7:41 am ] |
| Post subject: | Re: Weber Tuning Help Required |
I know it is not answering your questions, (sorry) but i think your symptoms are telling you the choke size is still too big, which unfortunately means the engine would prefer a weber DCOE 40 or dellorto 40 with say 30s. or even a 32-36DGV Low down tractability would never be classed as a weber strong point and i think the airflow dynamics/vacuum at the changover point is just out of ideal range. You obviously know what you are doing playing with these things, and i applaud your efforts, but given the car wont be always operating at redline, i think a 40 would be a better option. cheer Darryl |
|
| Page 1 of 2 | All times are UTC + 10 hours |
| Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/ |
|