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Post by Phil Nottingham on Mar 22, 2010 21:37:41 GMT
Correct and No just check jets as you say. It may be worth removing the dashpots and ensuring the pistons are free - clean any deposits off with thinners not abrasive.
Back smoke certainly points to overich mixutre and perhaps jets are wrongly adjusted? Basic setting on adjusting nut is 2½ turns down from fully up and follow standard SU setup with the piston lifters on the underneath. Count number of turns as is though to return it to existing settings if required
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Post by Warwick on Mar 23, 2010 0:01:01 GMT
Michael,
I've sent you a PM. I have a VACC tech bulletin on SU adjustment that I can e-mail to you.
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Post by johnwp5bcoupe on Mar 23, 2010 6:39:42 GMT
Michael, I've sent you a PM. I have a VACC tech bulletin on SU adjustment that I can e-mail to you. Sounds like a good one for a "Sticky"
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mjb59
Rover Fanatic
Posts: 311
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Post by mjb59 on Mar 23, 2010 7:16:21 GMT
Thanks very much Warwick. Does a PM mean you need my email address? Sorry John, what's a 'Sticky'?
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Post by johnwp5bcoupe on Mar 23, 2010 17:13:54 GMT
Thanks very much Warwick. Does a PM mean you need my email address? Sorry John, what's a 'Sticky'? Sticky is something of interest kept and not deleted so others can benefit from it
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mjb59
Rover Fanatic
Posts: 311
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Post by mjb59 on Mar 23, 2010 19:54:27 GMT
When I remove the cold start cables from each carb linkage and turn the linkage by hand as far as I can, the jet is not moving on either carb. The right hand carb jet is lower than the left, but neither moves whatever the position of the carb linkage. Is the cold start meant to lower the jet on each carb or only one? Presumably the jets are stuck? Is there a squirty product that unsticks them or do I need to dismantle the carbs?
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Post by Warwick on Mar 23, 2010 23:05:42 GMT
I got your PM Michael, so I guess you've figured that bit out. A sticky is the web forum equivalent of the sticky note. You'll find them at the top of each section, and as John says, they stay there. They don't get forced down the page and onto the next as new posts get added.
Certainly sounds like stuck jets and running rich. As you probably know, the partial vacuum created by the flow of air through the SU's throat causes the piston to lift and raise the needle from the jet. Since the needle is tapered, as it rises out of the jet, the gap around it gets bigger and more petrol is drawn out and into the airstream.
In order to enrich the mixture, the cold start mechanism lowers the jet thereby increasing the space around the needle before the needle rises. This alters the ratio of petrol to air over the full range of needle travel. It becomes richer. The jet should move down freely.
I had the opposite problem. One jet moved while the other rotated instead of lowering, so it was hard to start when cold. I couldn't see why it rotated when the lever tried to pull it down, but it did. Replacing the jets fixed it.
If the needles aren't centralized in the jet, they can rub on the side of the jet and this can inhibit piston lift. It might also hamper jet lowering. And it wears the needle.
John, I'll e-mail you the tech bulletin and you can figure out what to do with it. It's probably 30 or 40 years old and has the advantage that it was written for general motor mechanics, not specifically for dealers' mechanics, so it doesn't assume prior knowledge and it is clear and to the point. The other advantage is that it wasn't written by Rover or by SU. Genuine factory manuals sometimes gloss over or fail to mention things which to the writer are obvious, but may not be to the newcomer. It was written for our local mechanics so those of you who reside overseas should ignore references to removing wombat hair from the jet or getting huntsman spider egg-sacks out of the float chamber.
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Post by David on Mar 24, 2010 10:38:04 GMT
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Post by peeved on Dec 2, 2012 10:18:29 GMT
Hi MJB, I'm in Melbourne and experiencing something similar. 69 P5B coupe, just fitted 3.9 motor which had minor rebuild. Oil light goes off in a timely manor, but oil pressure gradually builds up and heads for high. I have SDI front cover fitted, with P5B oil pump housing. So far I have replaced pressure relief valve for tap pole (lapped in to ensure no bled back of oil from pump), replaced pressure sender (though it was with another second hand one I had in my collections of bits and pieces). I have primed pump with vaseline and used special tool to prime via distributor hole. All to no avail. I have oil at the rocker covers - both banks. So I assume my oil ways are clear??? Any way to clear them without having the block chemically dipped? Tried two oil pressure gauges both read high. I haven't let the engine run for more than couple of minutes as I'm concern about damaging it. Should I let it warm up and see what happens? Where can i source a mechanical oil pressure gauge with necessary connector to fit into Rover pump housing?
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Post by Phil Nottingham on Dec 2, 2012 10:55:55 GMT
High oil pressure is unlikely and damage is unlikely to happen but a gasket may spring a leak so it needs sorting. Never rely on the gauge anyway - fit a mechanical one - see Vehicle Wiring Products or Holdens - they do the adaptors as well. You can even fit the original face/bezel if you are careful.
It could be more serious but getting a true pressure reading is an essential first to to try before anything else as it will entail an engine strip
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Post by poodumrover1 on Sept 1, 2013 19:49:27 GMT
Hi MJB, I'm in Melbourne and experiencing something similar. 69 P5B coupe, just fitted 3.9 motor which had minor rebuild. Oil light goes off in a timely manor, but oil pressure gradually builds up and heads for high. I have SDI front cover fitted, with P5B oil pump housing. So far I have replaced pressure relief valve for tap pole (lapped in to ensure no bled back of oil from pump), replaced pressure sender (though it was with another second hand one I had in my collections of bits and pieces). I have primed pump with vaseline and used special tool to prime via distributor hole. All to no avail. I have oil at the rocker covers - both banks. So I assume my oil ways are clear??? Any way to clear them without having the block chemically dipped? Tried two oil pressure gauges both read high. I haven't let the engine run for more than couple of minutes as I'm concern about damaging it. Should I let it warm up and see what happens? Where can i source a mechanical oil pressure gauge with necessary connector to fit into Rover pump housing? I am based in Ireland, having installed a 3.9 from NEW with P5b front cover & Oil pump - however I too am experiencing high oil pressure on the guage. Similarly I have changed the valve release spring and plunger without any change. Since then I have put 12,000 miles on Sheeba since restoration, however I have noticed when cruising approx. 60mph revs @ 2,000 - 2,200 I am getting lifter clacking intermittently (sounds like a Spanish Castanet player). I have since replaced the lifters and still now improvement - I am wondering could the "apparent" high oil pressure be real and causing the problems ... Just wondering if anyone had any ideas or would like to comment ? Many thanks. Stephen Callaghan AKA: PoodumRover1
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