moomin
Part of things
Posts: 772
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Dec 15, 2014 20:06:35 GMT
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Evening all,
Can anyone explain the difference in exhaust note side to side? Just firing order, carbs? Both? Something else?
Exhausts are identical side to side.
Can hear the passenger side crackles more.
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Last Edit: Dec 15, 2014 20:07:08 GMT by moomin
@toxicknobs
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Smiler
Posted a lot
I no longer own anything FWD! Or with less than 6 cylinders, or 2.5ltrs! :)
Posts: 2,492
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Dec 15, 2014 22:26:49 GMT
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Sound of passenger side bouncing off the wall of the house whereas the sound from the drivers side is being absorbed by the hedge?
Or is it the same on the open road?
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www.Auto-tat.co.uk'96 Range Rover P38 DSE (daily driver) '71 Reliant Scimitar SE5 GTE 3.0ltr Jag V6 Conversion '79 Reliant Scimitar SE6A 3.0ltr 24valve Omega Conversion '85 Escort Cabrio 2.0 Zetec - Sold '91 BMW 525i - Sold '82 Cortina 2.9i Ghia Cosworth - Sold '72 VW Campervan - Sold '65 LandRover 88" - Sold
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Dec 15, 2014 23:12:53 GMT
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I think for better running you should have a balance pipe between the two sides of the exhaust system. It may alter the cool sound but should help the engine run better.
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moomin
Part of things
Posts: 772
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Dec 16, 2014 17:08:23 GMT
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Sound of passenger side bouncing off the wall of the house whereas the sound from the drivers side is being absorbed by the hedge? I wonder if it is that I'll move it and see |
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@toxicknobs
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bobajob
Part of things
Everybody's entitled to my opinion...
Posts: 23 
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Dec 16, 2014 22:15:41 GMT
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A bit far fetched perhaps but if there's a distinct difference in sound between the two banks of cylinders it might down to cam timing. if the cam timing on one bank of cylinders is slightly out it might sound a bit flat.
Bob
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steveg
Posted a lot
Posts: 1,586
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Dec 17, 2014 19:02:01 GMT
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Have V12's got two sets of points ? I was just wondering if setting them using a dwell meter rather than just setting the gap might help assuming the have two sets that is.
I imagine setting the carbs up is a bit of a nightmare as well. Have you balanced all the carbs and used a gas tester or colourtune to try and match them up ?
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Dec 17, 2014 21:04:26 GMT
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check for exhaust gasket failure !
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moomin
Part of things
Posts: 772
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Dec 17, 2014 21:05:08 GMT
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Have V12's got two sets of points ? I was just wondering if setting them using a dwell meter rather than just setting the gap might help assuming the have two sets that is. I imagine setting the carbs up is a bit of a nightmare as well. Have you balanced all the carbs and used a gas tester or colourtune to try and match them up ? No points, it's Opus ignition system. 12 ferrite rods whiz past a sensor then into a magic box before triggering a singular coil! Good for 12000rpm apparently. Gas Analyser could be a good call. If only the sun didn't set at midday I'd be able to get it done! I hate the winter. It has no chokes so requires an exciting and very noisy warmup sequence which my neighbours love  I will get it out on the road for a good thrash this weekend! |
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@toxicknobs
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steveg
Posted a lot
Posts: 1,586
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Dec 17, 2014 21:40:34 GMT
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It does sound nice though, I went searching for v12 clips on youtube after hearing yours. I don't like Strombergs much having struggled with them on my Triumph 2000. I found a little tool used to set the height of the dashpot pistons while the engine was running. You are supposed to adjust the idle stop to to match them up. Thats fine as long as the needles haven't worn differently.
I ended up getting a pair of SU's as you have a bit less to worry about.
If there is a problem I hope you sot it out, it's an excuse for a blat about in it though !
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Dec 17, 2014 21:46:08 GMT
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nice project, love the v12 burble......
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I like V12's.... but mine is 185 litre diesel....
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Rover Metro - The TARDIS - brake problems.....Stored
Rover 75 - Barge
MGZTT Cdti 160+ - Winter Hack and Audi botherer...
MGF - The Golden Shot...Stored
Project Minion........
Can you see the theme?
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deffo sounds akin to a fuelling issue - so most likely one of the carbs out of kilter to the rest.
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You're like a crazy backyard genius! |
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moomin
Part of things
Posts: 772
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Dec 18, 2014 17:44:32 GMT
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One last attempt this weekend with new linkage components between the carbs as I the current setup slips and they go out if sync.
Maybe it's time to think about an alternative fuelling system. If only it wasn't so pricey. 12 of anything is a pain.
Perhaps 12 bike carbs?
4x triples or can you split a bank of 4 in half?
Do you even get down draught bike carbs?
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@toxicknobs
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mylittletony
Posted a lot
Posts: 2,415
Club RR Member Number: 84
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Dec 18, 2014 17:55:22 GMT
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Perhaps 12 bike carbs? 4x triples or can you split a bank of 4 in half? Do you even get down draught bike carbs? Ballsy!! I like it. Quite a few bikes used downdraft carbs or you could do a crossfire type inlet? triumph do/did a number of triples... |
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it's not that easy to find bike carbs that are side draught  Most are splitable, but the linkages are very delicate and fiddly. probably best just to get what you have working for now. but it would be flipping unbelievable to hear twelve bike carbs  |
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mylittletony
Posted a lot
Posts: 2,415
Club RR Member Number: 84
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a man of moomin's fabrication talent could probs knock up a custom inlet  how about 3 downdraft webers?? |
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Dec 19, 2014 12:01:31 GMT
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the firing order seems to go left bank, right bank, left bank, right bank. and so on, fairly regular
then if you grouped the cylinders into 4 lots of 3 as per the exhaust collectors (question don't know what you have), it goes left front, right back, left back, right front and repeat. so each collector is getting a puff per cycle, and each of 4 secondaries 2 puffs each per cycle.
i understand the concept of exhaust balancer pipes (in terms of total engine output) but cant see a reason for an off beat thrum all being well?
unlike, say, boxer subaru engine which goes left bank left bank, right bank right bank.
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moomin
Part of things
Posts: 772
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Dec 20, 2014 18:35:22 GMT
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the firing order seems to go left bank, right bank, left bank, right bank. and so on, fairly regular then if you grouped the cylinders into 4 lots of 3 as per the exhaust collectors (question don't know what you have), it goes left front, right back, left back, right front and repeat. so each collector is getting a puff per cycle, and each of 4 secondaries 2 puffs each per cycle. i understand the concept of exhaust balancer pipes (in terms of total engine output) but cant see a reason for an off beat thrum all being well? unlike, say, boxer subaru engine which goes left bank left bank, right bank right bank. Standard manifolds yes. I'm not adding a balancing pipe. Don't think the Xjs or e-type combined systems? Might be the cherry bomb. Was cheap so maybe just less packing in it. |
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@toxicknobs
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Dec 21, 2014 11:23:51 GMT
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Difference in timing, fueling or compression all create a difference in efficiency and that's what you hear. Could even be a leaky valve somewhere. But since you're still having carb issues (right?) I'm guessing that's where the most is to be gained.
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Dec 21, 2014 14:38:30 GMT
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having listened to the video with decent sound system (rather than just theorycrafting) it does sound a bit thrappy on the nearside, with a rather more woomphy noise on the offside
sounds lovely and smooth though compared to the early videos at start of the diary thread, some good work done so far on the fuelling.
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