| ausmini https://www.ausmini.com/forums/ |
|
| 1275 - which distributor? https://www.ausmini.com/forums/viewtopic.php?f=2&t=100482 |
Page 1 of 1 |
| Author: | Gambo [ Mon Oct 26, 2020 10:58 am ] |
| Post subject: | 1275 - which distributor? |
Hi brains trust. Just after some opinions/recommendations/thoughts on what distributor I should be running. At the moment it's a 45D (with vac advance and electronic conversion), but I'm thinking this might not be the best choice. Running a 1275 with a 45 DCOE,LCB extractors - not sure on the cam specs as it was the one that came with the engine.Timing is set at 12 degrees@1000rpm with vac advance disconnected. At the moment, if I disconnect the vac advance, it runs like a pig (yes I know I shouldn't be running the vac advance with the Weber). When i take it for a run with the advance disconnected (and hose blocked off so no air leak), it pops and farts at light throttle. I've made sure the carby jetting, etc is fine. Connect the advance and it's happy. Now, based on this I am wondering if I made the wrong choice of dizzy. Should I be running something like the 23D (that has no vac advance)? Or am I way off the mark and just try and get it working OK with the 45D (with vac advance disconnected)? Or is there a different one I should use that would be better with my combo? Curious to hear from others running a similar combo to see what dizzy they are using. |
|
| Author: | MINI66 [ Mon Oct 26, 2020 11:25 am ] |
| Post subject: | Re: 1275 - which distributor? |
Hey Gambo I have the same setup (1275 - 45dcoe) running a re-graphed Pulsar dizzy with the following timing. Mild cam (No vac adv) 1000rpm/idle - 15-16deg adv 2800rpm - 34-35deg adv (all in max advance) (So around 20deg of mechanical advance in the dizzy) This works really well in my case. Shouldn't matter what dizzy as long as your advance curve is right. Most of the other examples of similar setup that I have seen have all in max advance by about 3500rpm. My advice would be to try some more idle advance and check the dizzy to confirm that the mechanical advance is working properly. If it starts to ping under load or is very hard to crank you have gone too far. Also confirm that your timing mark is correct. (Clutch cover inspection hole v's crank pulley v's number 1 at tdc (look down plug hole)) I have also seen DCOE setups running fine with vac advance as long as it is plumbed to both sides of the manifold. Note that Vac advance is only supposed to come in under cruise/hi vacuum situations, not under load, so the vac signal from the weber or the dizzy setup must be screwed up to give advance under load. cheers Rick |
|
| Author: | Gambo [ Mon Oct 26, 2020 12:09 pm ] |
| Post subject: | Re: 1275 - which distributor? |
Thanks Rick, appreciate the input. I checked the static timing when I installed the dizzy so it *should* be right - once I find my inspection mirror I will double check it. When i stick a timing light on it, it seems to be sitting at around 16 deg with the vac advance connected at idle - should I try bumping it up to 15/16 at idle without the vac advance? May have to Macgyver something up to connect it to both ports, as i've got the brake booster connected to one side of the manifold. Might be better off having both the booster and vac advance connected to both. And I've seen what you mentioned about being all in at 2800 rpm - again, i'll check this with the vac advance disconnected and see if i'm getting 20deg at the same revs. Just out of curiosity, what are your jet sizes? MINI66 wrote: Hey Gambo
I have the same setup (1275 - 45dcoe) running a re-graphed Pulsar dizzy with the following timing. Mild cam (No vac adv) 1000rpm/idle - 15-16deg adv 2800rpm - 34-35deg adv (all in max advance) (So around 20deg of mechanical advance in the dizzy) This works really well in my case. Shouldn't matter what dizzy as long as your advance curve is right. Most of the other examples of similar setup that I have seen have all in max advance by about 3500rpm. My advice would be to try some more idle advance and check the dizzy to confirm that the mechanical advance is working properly. If it starts to ping under load or is very hard to crank you have gone too far. Also confirm that your timing mark is correct. (Clutch cover inspection hole v's crank pulley v's number 1 at tdc (look down plug hole)) I have also seen DCOE setups running fine with vac advance as long as it is plumbed to both sides of the manifold. Note that Vac advance is only supposed to come in under cruise/hi vacuum situations, not under load, so the vac signal from the weber or the dizzy setup must be screwed up to give advance under load. cheers Rick |
|
| Author: | MINI66 [ Mon Oct 26, 2020 1:12 pm ] |
| Post subject: | Re: 1275 - which distributor? |
Personally, I wouldn't use the vac advance as it is one more variable to go wrong and you will only get marginally better fuel economy and on highway cruise only. Disconnect the Vac advance and dial in some more idle timing. my weber jetting: 1275 (1100s engine) - Stock cam/head - 20 thou over - Headers and Maniflow 1 & 7/8 twin box. Choke - 34 Aux - 5.0 Main - 145 Air - 190 Idle - 40F8 Em Tube - F16 Pump Jets - 30 (smallest you can get) Pump Bleed - Blocked Idle screws - 1.5 turns (late design screws) AFR Idle 13.5-14.0 Slow cruise 13.5 (60kms) Fast cruise 14.0 (110kms) WOT 12.0 to 12.5 cheers Rick |
|
| Author: | Gambo [ Mon Oct 26, 2020 1:28 pm ] |
| Post subject: | Re: 1275 - which distributor? |
Thanks Rick - looks we are pretty close on the jetting. I'll give your suggestion to dial in a bit more advance at idle a go this weekend. MINI66 wrote: Personally, I wouldn't use the vac advance as it is one more variable to go wrong and you will only get marginally better fuel economy and on highway cruise only.
Disconnect the Vac advance and dial in some more idle timing. my weber jetting: 1275 (1100s engine) - Stock cam/head - 20 thou over - Headers and Maniflow 1 & 7/8 twin box. Choke - 34 Aux - 5.0 Main - 145 Air - 190 Idle - 40F8 Em Tube - F16 Pump Jets - 30 (smallest you can get) Pump Bleed - Blocked Idle screws - 1.5 turns (late design screws) AFR Idle 13.5-14.0 Slow cruise 13.5 (60kms) Fast cruise 14.0 (110kms) WOT 12.0 to 12.5 cheers Rick |
|
| Author: | MINI66 [ Mon Oct 26, 2020 2:01 pm ] |
| Post subject: | Re: 1275 - which distributor? |
Ok, no worries What are your jetting differences, if any? I was surprised that my pump jetting was so small. I notice that starting is not as consistent as with su's. Cold start needs choke for me (or 5+ pedal pumps which is not practical) and warm start can crank for a while and need about 1/4 pedal. Can flood it with 2-3 pumps when warm. Certainly doesn't start first kick like an SU but everything else is soo much better. (Perfect consistent fueling, no oil/springs to mess about with and great sound) |
|
| Author: | Gambo [ Mon Oct 26, 2020 2:21 pm ] |
| Post subject: | Re: 1275 - which distributor? |
This is what i'm running and it seems reasonably happy - but once i get the timing/dizzy sorted, likely all needs a revisit. I would say it's probably running on the rich side at the moment. I reckon the idle jet can come back down to at least a 45. Choke - 34 Aux - 4.5 Main - 140 Air - 190 Idle - 50F2 Em Tube - F9 (but may change to the F16) Pump Jets - 40 - was a 45 but dropped it down and the response is a lot better. Pump Bleed - Blocked off as well Choke is blanked off so just needs a couple of squirts for cold start, and a few minutes to warm up - had to block it off as it was leaking fuel due to the manifold angle. Warm start is one squirt and good to go. I think your pump jet may be so small because you are running such a large aux - that's what i found when i had the 45 in there - hit the pedal and it just bogged down until the air speed caught up. Switched it to the 40 and made a huge difference. And agree - you can't beat the sound (once you get the bloody thing running right!) |
|
| Author: | MINI66 [ Mon Oct 26, 2020 2:32 pm ] |
| Post subject: | Re: 1275 - which distributor? |
ok thanks. Yeah, i started with a 45 pump and the AEM wideband would go off scale pig rich when foot down on pedal. Now it is perfect (can get to 11:1 on a big wide open throttle but that's good enough - cant buy any smaller anyway) My lean idle jet(compared to yours) could also be the cause of difficult starting. It is definitely a lean tune compared to most of the mini's running a dcoe. Anyway it always eventually starts! |
|
| Author: | Gambo [ Mon Oct 26, 2020 2:37 pm ] |
| Post subject: | Re: 1275 - which distributor? |
It doesn't help that the idle jet numbering etc isn't actually sequential...... I found this web page which actually does a good job of explaining it all. https://cnx.org/contents/oKbaEWQ3@2/Sel ... 6626978105 |
|
| Author: | Gambo [ Mon Nov 02, 2020 8:04 am ] |
| Post subject: | Re: 1275 - which distributor? |
Over the weekend I double checked static timing, made sure everything was good in the dizzy - found a wire that had been caught by the cap and took some of the insulation off. Bit of heat shrink fixed that. Disconnected and plugged the vac advance as well. Dialed up the timing to 16 degrees at idle, and whoo boy that made a difference. Much happier now, seems to have picked up some bottom end torque as well. |
|
| Author: | MINI66 [ Mon Nov 02, 2020 10:35 am ] |
| Post subject: | Re: 1275 - which distributor? |
Good news. Webers typically need more advance than SUs as they are not a cv type carb. A rough way to check the mechanical advance curve is to have a remote tacho (most dwell meters have these) and setup the timing light also and watch the tacho and timing and write what you see down. You may have already done this. |
|
| Author: | Gambo [ Mon Nov 02, 2020 10:58 am ] |
| Post subject: | Re: 1275 - which distributor? |
MINI66 wrote: Good news. Webers typically need more advance than SUs as they are not a cv type carb. A rough way to check the mechanical advance curve is to have a remote tacho (most dwell meters have these) and setup the timing light also and watch the tacho and timing and right what you see down. You may have already done this. Thanks again for the advice Rick! Much happier with how it's running now - still need to tweak the jetting a little bit, but overall a vast improvement over what it was. No stumbling, popping etc. Absolutely screams in the 60-110kph range now. The mech advance is kicking in nicely. I added a second mark to the crank pulley so I could easily check what the advance is now using the existing timing marks. |
|
| Author: | MINI66 [ Mon Nov 02, 2020 11:01 am ] |
| Post subject: | Re: 1275 - which distributor? |
ok, cool no worries |
|
| Page 1 of 1 | All times are UTC + 10 hours |
| Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/ |
|