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Post by Zed on Mar 15, 2018 18:11:53 GMT
Holy mindfuck Zedman !!!! I read the whole thread on the samba over a couple of days I kept having to stop for a while as it certainly takes some getting through. I do like threads that I learn from like that though. I’ll be following along with zed aswell as I’ve got a set of kadrons to go on my engine some time in the future When it comes to jetting them I think I’d be better of doing it myself this way. Rolling road time doesent come cheap. Although not enough, there are several mentions and one chap getting quite excersised about lean running in a bus as opposed to a car and that some of thr ratios quoted could kill your bus engine. I think I'm going to take the cruising afr numbers with a pinch of salt. There are video link on one post to someone driving a bus with a vacuum gauge tee'd into the advance pipe, I don't know what his engine is but he had vacuum cruising at 60-65-70mph. I'm reading all for the second time...
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Post by Zed on Mar 15, 2018 18:12:31 GMT
Can't believe you lot didn't know all of that already. Simple stuff! Twat!
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Post by paradox1001 on Mar 15, 2018 20:52:28 GMT
I read the whole thread on the samba over a couple of days I kept having to stop for a while as it certainly takes some getting through. I do like threads that I learn from like that though. I’ll be following along with zed aswell as I’ve got a set of kadrons to go on my engine some time in the future When it comes to jetting them I think I’d be better of doing it myself this way. Rolling road time doesent come cheap. Although not enough, there are several mentions and one chap getting quite excersised about lean running in a bus as opposed to a car and that some of thr ratios quoted could kill your bus engine. I think I'm going to take the cruising afr numbers with a pinch of salt. There are video link on one post to someone driving a bus with a vacuum gauge tee'd into the advance pipe, I don't know what his engine is but he had vacuum cruising at 60-65-70mph. I'm reading all for the second time... I think it’s the what’s considered as Under load that muddies the waters Anything throat side of the air filter will always pull a certain amount of vacuum
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Post by paradox1001 on Mar 15, 2018 21:40:20 GMT
Although not enough, there are several mentions and one chap getting quite excersised about lean running in a bus as opposed to a car and that some of thr ratios quoted could kill your bus engine. I think I'm going to take the cruising afr numbers with a pinch of salt. There are video link on one post to someone driving a bus with a vacuum gauge tee'd into the advance pipe, I don't know what his engine is but he had vacuum cruising at 60-65-70mph. I'm reading all for the second time... I think it’s the what’s considered as Under load that muddies the waters Anything throat side of the air filter will always pull a certain amount of vacuum What a lot of people don’t realise is there’s a lot more happening in a carb throat than just suction There’s a bubble of air,fuel above the top of a carb during certain conditions
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Post by Zed on Mar 19, 2018 17:54:32 GMT
I find JK have Ernst exhausts and after double checking and still not really believing them I've ordered a kit anyway. Getting one of these was a problem when I built up my engine and I had to repair an old one. Part of the repair was welding the tail pipe on and now of course I want to get it off to make my sensor boss fitting more convenient.
This tuning malarky is starting to add up but I still believe it's justifiable expense. If I can improve by 4mpg I save £40/1000 miles so after a year I'll have covered the exhaust and afr install and no doubt my engine will last longer too. Hopefully. Even 2mpg would be worth the effort.
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Eoin
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Post by Eoin on Mar 19, 2018 18:34:11 GMT
Although not enough, there are several mentions and one chap getting quite excersised about lean running in a bus as opposed to a car and that some of thr ratios quoted could kill your bus engine. I think I'm going to take the cruising afr numbers with a pinch of salt. There are video link on one post to someone driving a bus with a vacuum gauge tee'd into the advance pipe, I don't know what his engine is but he had vacuum cruising at 60-65-70mph. I'm reading all for the second time... I think it’s the what’s considered as Under load that muddies the waters Anything throat side of the air filter will always pull a certain amount of vacuum The low throttle / cruising rpm and pick up from idle are really hard to tune right. It's not just about AFR, it's also about pickup and feel. On mine, the RR tune I had done was shit, I could do it better myself using a data log. What you don't easily get are the transitions, unless you've got someone expeienced next to you making chnages on the fly until it feels right as well as looks right on the AFR. With carbs, there's going to be a lot of trial and error involved.
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Eoin
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Post by Eoin on Mar 19, 2018 18:38:07 GMT
I find JK have Ernst exhausts and after double checking and still not really believing them I've ordered a kit anyway. Getting one of these was a problem when I built up my engine and I had to repair an old one. Part of the repair was welding the tail pipe on and now of course I want to get it off to make my sensor boss fitting more convenient. This tuning malarky is starting to add up but I still believe it's justifiable expense. If I can improve by 4mpg I save £40/1000 miles so after a year I'll have covered the exhaust and afr install and no doubt my engine will last longer too. Hopefully. Even 2mpg would be worth the effort. Can you get a data logger on your phone to read the AFR? Then you can look at how the mix changes during on / off throttle transitions - if it leans out when you boot it etc.
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Post by Zed on Mar 19, 2018 19:31:35 GMT
I find JK have Ernst exhausts and after double checking and still not really believing them I've ordered a kit anyway. Getting one of these was a problem when I built up my engine and I had to repair an old one. Part of the repair was welding the tail pipe on and now of course I want to get it off to make my sensor boss fitting more convenient. This tuning malarky is starting to add up but I still believe it's justifiable expense. If I can improve by 4mpg I save £40/1000 miles so after a year I'll have covered the exhaust and afr install and no doubt my engine will last longer too. Hopefully. Even 2mpg would be worth the effort. Can you get a data logger on your phone to read the AFR? Then you can look at how the mix changes during on / off throttle transitions - if it leans out when you boot it etc. Seems to me without logging rpm and throttle position there's not much help in logging afr so I'll just look at it. The samba thread is really about webers, which have tricky to tune transition. Dellotos are easier (because they're better!), the idle air size is fixed as it's a hole through the casting. That means you can't move the transition by changing both the idle air and fuel jets, just get the mix right by changing the fuel idle jet in relation to the fixed idle air. As it fepends on engine vacuum rather than venturi size, it's almost always 55 or 57 for every engine with drla40's! Dellortos also have more transition holes and are known for their smooth transition. Whereas you can bugger about with webers moving where the mains come in by changing the main airs, it's universally accepted that dells always work best with 180 airs (or is it 190?) which I have fitted. Therefore I'm expecting a smooth transition without doing anything. So really I hope all I'll be doing is messing about with idle (slightly), then messing with main and venturi sizes. That's the plan anyway! The timing I'll get as retarded as my lowish compression engine will take, then leaner, then less timing etc. If thateans the tickover advance is to small I'll look into limiting the range of the mech advance by use of a screw - there's a slot seemingly for such a screw to run in though I haven't looked into it. After or during that I might be tempted with proper ignition, the distributor is rough compared to a 123 even, but I quite fancy one of those megawotsit system with a crank trigger. One thing at a time, I might be happy with the right jetting and timing range.
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Eoin
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Post by Eoin on Mar 19, 2018 20:55:02 GMT
Can you get a data logger on your phone to read the AFR? Then you can look at how the mix changes during on / off throttle transitions - if it leans out when you boot it etc. Seems to me without logging rpm and throttle position there's not much help in logging afr so I'll just look at it. The samba thread is really about webers, which have tricky to tune transition. Dellotos are easier (because they're better!), the idle air size is fixed as it's a hole through the casting. That means you can't move the transition by changing both the idle air and fuel jets, just get the mix right by changing the fuel idle jet in relation to the fixed idle air. As it fepends on engine vacuum rather than venturi size, it's almost always 55 or 57 for every engine with drla40's! Dellortos also have more transition holes and are known for their smooth transition. Whereas you can bugger about with webers moving where the mains come in by changing the main airs, it's universally accepted that dells always work best with 180 airs (or is it 190?) which I have fitted. Therefore I'm expecting a smooth transition without doing anything. So really I hope all I'll be doing is messing about with idle (slightly), then messing with main and venturi sizes. That's the plan anyway! The timing I'll get as retarded as my lowish compression engine will take, then leaner, then less timing etc. If thateans the tickover advance is to small I'll look into limiting the range of the mech advance by use of a screw - there's a slot seemingly for such a screw to run in though I haven't looked into it. After or during that I might be tempted with proper ignition, the distributor is rough compared to a 123 even, but I quite fancy one of those megawotsit system with a crank trigger. One thing at a time, I might be happy with the right jetting and timing range. If you use your tach and remember revs and location (so you can duplicate) then an AFR log will be useful. Lean = more timing due to slower burn. Come over and see the crank trigger setup of you want, I can get the fan off in 2 minutes.
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Post by Zed on Mar 20, 2018 8:28:44 GMT
If you use your tach and remember revs and location (so you can duplicate) then an AFR log will be useful. Lean = more timing due to slower burn. Come over and see the crank trigger setup of you want, I can get the fan off in 2 minutes. I thought rich = more timing (advance)? I think this is where I'm at right now. Any pics of your crank trigger set up?
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Eoin
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Post by Eoin on Mar 20, 2018 8:38:38 GMT
If you use your tach and remember revs and location (so you can duplicate) then an AFR log will be useful. Lean = more timing due to slower burn. Come over and see the crank trigger setup of you want, I can get the fan off in 2 minutes. I thought rich = more timing (advance)? I think this is where I'm at right now. Any pics of your crank trigger set up? Leaner = more advance. The lean mix burns slower, so needs a bit more time to get going. This is when you are working on low throttle cruise. STF has a lot of info. What's the best way to post pics? Might have one, otherwise will get one when I work on the van next.
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Post by Zed on Mar 20, 2018 9:46:58 GMT
Still fink you have it the wrong way round, weak gives more of a bang, rich is slower burn. John's posts above describe peeps over fuelling and setting more advance to compensate?
Low compression also likes more advance on the "advance causes higher compression theory", i.e. the burning fuel creates compression while the piston is heading up to TDC. Too much and it fights itself needing ever richer mix and more and more advance, but clearly wasting fuel working against itself.
Tapatalk is an easy way to put pics directly into a post.
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Post by Zed on Mar 20, 2018 9:51:05 GMT
Exhaust should arrive today, I guess I should strip it and paint with vht paint. Bum. Meanwhile I can get the boss welded on the tail pipe before painting that too.
Battery on charge ready for some compression testing. I don't think there's anything wrong but it's wise to check before all my intended messing about ends up going round in circles.
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Post by chad on Mar 20, 2018 10:38:23 GMT
I know that this is a bit off topic but did you get to the bottom of your front suspension woes?
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Post by Zed on Mar 20, 2018 11:59:19 GMT
I know that this is a bit off topic but did you get to the bottom of your front suspension woes? No, it goes straighter now but it's wobblier if that makes sense. One day I'll have to dismantle the beam. I do know one side camber is right with adjuster approximately centred and the other is set to max. There must be a clue there : a bent arm perhaps.
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