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Post by eightofthem (Andy) on May 4, 2009 10:55:12 GMT
Chaps, im almost talking myself into removing the cylinder heads to see whats going on!.
v8 is running a bit lumpy,plugs show sooty on 6,3+5 all others good,its had new plugs,leads, carbs rebuilt+balanced,mixture set, timing sorted. My only concern before i do a compression test and strip is this. I put a mallory electronic ignition on it,but it does not have the vacuum unit on,does this engine need it?. Engine seems to be in good overall condition very clean no rattles no smoke,starts well and ticks over,all be it a bit lumpy,with vibration under acceleration (due to not firing right i guess which is why i ask about the vacuum). Anyone.
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Post by Phil Nottingham on May 4, 2009 11:11:29 GMT
The vacuum unit only operate under overrun to give more economy and smoothness. If it is not fitted it will not affect acceleration.
Have you checked the centrifugal weights are free under the baseplate and renewed the rotaarm & cap?
Always do a compression checkfirst unless you are certain its not a head or piston etc problem
Is it the original camshaft?
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Post by eightofthem (Andy) on May 4, 2009 11:25:20 GMT
Hi phil,distributor and components are new,i think the camshaft is original and the car has just done the clock once,I am also leaning towards the cam,but i have late RR heads to go on one day so may well do it all in one go.Looks like i am going to get oily.
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Post by enigmas on May 4, 2009 13:49:33 GMT
The vacuum unit advances the ignition under cruise conditions (steady throttle) when there is a good vacuum signal from the engine. Properly setup it will improve the fuel economy and burn within the engine.
If the plugs are sooty its usually an overly rich mixture, if they are oily, wet (blackish) its probably burning oil.
Who did the work on the engine?
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Post by Colin McA on May 4, 2009 14:23:30 GMT
Get a colour tune and compare the colour of each cylinder.
If your engine is original you may/will have wear to the camshaft and followers. this will mean that the valves don't fully open.
Does the car start easily? does it take a good few turns of the engine.
Colin
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Post by Smallfry on May 4, 2009 14:40:35 GMT
The camshaft will be shot would be my guess.
Although you can set the timing properly, you cannot really set the mixture, and especially not the carb balance anything like properly.
Reason being, is although you can get a "proper" reading on the gauge, you are tyrying to compensate for some cylinders not taking as much air as others, and consequentially throwing airflow to some wildly out.
I suppose the Mallory was at the "recommendation" of a certain Norfolk based V8 "specialist"
You can do a compression test, which will help, but will not give the full story. If it were me, I would whip off the manifold and have a look. This problem is by far the Rover V8s biggest problem, so I would look at it first.
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Post by eightofthem (Andy) on May 4, 2009 16:46:15 GMT
Enigmas, only three plugs sooty, I have done all the work so far,burns no oil,looses no water does not overheat.
colin,car starts 5 seconds on the key with a bit of choke
smallfry,your comments are accurate,i did have a very hard time setting timing,idle,mixture etc especially balance on the carbs,(although me balancer is not up to much). As far as the "mallory" that was my choice, as one came my way at the right price,and the original dizzy was completely shot. I had the inlet manifold off to replace it and all looked well with the cam as far as i could see,but to compere it with a new one would show its faults i suppose.
Thanks for all your views it all really helps.
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Post by Phil Nottingham on May 4, 2009 22:26:08 GMT
Cam will be worn if its the original - it will be obvious though which lobes have gone on the faulty cylinders and by comparing them with the others
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Deleted
Deleted Member
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Post by Deleted on May 6, 2009 21:17:32 GMT
Camshafts can go at any mileage due to manufacturing faults like case hardening, oil changes and humidity caused by short runs. Once the case hardening wears through, wear is extremely fast. Always change the followers with a new camshaft. No need to lift the heads.
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Post by eightofthem (Andy) on May 7, 2009 20:23:58 GMT
I removed the plugs tonight,have a look at them,the plugs that came out of numbers 3 and 5 cylinders are very sooty in relation to all the rest,which leads me in the direction of the cylinder head gasket on that side between those two bores. I have not done a compression test yet, i will pick up a tester on the weekend.   |
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Post by Smallfry on May 7, 2009 21:39:51 GMT
Could be, but none of them are the same really, a couple of them don't look like they are burning much fuel at all.
As you have to take off the manifold to take off the heads, you might as well look at the camshaft, and compare the lobe shapes carefully.
As you will have gone this far, you might as well do the head gaskets anyway, for the sake of a couple more hours work.
These engines are not really prone to head gasket failure, not between the cylinders, in any case. My money is still on the camshaft.
Try a compression test ? I suspect a test will be inconclusive, or the cylinder/s with no deposits on the plug/s will be the ones that are down on pressure.
If it IS those two cylinders down, then of course you should look at the gasket.................but I would still check the camshaft carefully.
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Post by Phil Nottingham on May 7, 2009 22:21:29 GMT
Its not a carb issue as 3 & 5 are fed by different ones
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Post by eisdielenbiker on May 8, 2009 6:57:07 GMT
They 2 plugs dont look that bad. 1 or 2 of my P5B also look like that. My number 2 is even more oily. And the engine runs rather fine besides consuming more and more oil. A compression test is what I am about next.
Mark
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Post by enigmas on May 8, 2009 12:01:18 GMT
Eightofthem, since you state the engine seems to function well in other respects there are a few checks you can do.
When you first start the engine from cold does it idle well and then as it warms the idle quality starts deteriorating? (Note this.)
If you then hold the engine at a constant throttle at points between 1200rpm - 2500rpm does the engine run fine and evenly on all cyls? If so it's a mixture problem at idle.
All V8 twin plane manifolds (not just Rover) distribute mixture unevenly at varying rpms. Hence you will get slight mixture variations when reading the plugs. I think you're currently reading the plugs after extended periods of idling. Not good. All this is indicating is poor mixture distribution due to a number of currently unrecognized or undiagnosed problems.
Remove, clean and refit the plugs. Don't idle the car if possible for any length of time. Get a plug spanner and drive to a freeway. Drive along the freeway at cruise speeds for 10 or 15 minutes. Decide where you can pull over to the side of the road (without endangering you life!). You need to switch the engine off while at speed and coast to the side of the road. Now remove the plugs and you will have an indication of the burn in the cyls. If you allow the engine to idle your results will be inaccurate.
Don't remove the heads unless you enjoy the process or have an overwhelming desire to 'check-out' the pistons!
From your explanation and I think Smallfry nailed it... you had a lot of trouble setting the mixtures. Idle is most critical...most things above it less so with SU carburettors.
You would have needed to disconnect the linkage between the 2 carbs to get the balance correct? If your hearing is still OK a section of garden hose can do the job. (Do you know how to do this?)
One last thing have you checked the resistance of each of your plug leads. If you have a multi-meter, set it to ohms and compare resistance of similar length leads. There is a value for different types of lead and a scale for differing lengths. If you have someone hold the probes at either end while you flex the remainder of the lead and the resistance value varies the lead is shot.
Also try the midnight test. Start the car in a very dark place (its up to you how you manage this) and note any glowing or shorting of the leads...you'd be surprised what can be seen. Nothing should glow! ~ Vince
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Post by harvey on May 8, 2009 13:55:49 GMT
Its not a carb issue as 3 & 5 are fed by different ones 3 & 5 are fed by the same carb. (The O/S, right hand, one) |
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Post by johnwp5bcoupe on May 8, 2009 16:07:44 GMT
Its not a carb issue as 3 & 5 are fed by different ones 3 & 5 are fed by the same carb. (The O/S, right hand, one) On the ball harvey  B****r this is a wide posting need a bigger screen ;D |
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Post by eightofthem (Andy) on May 8, 2009 16:39:05 GMT
Hi Enigmas,i did the "midnight test" on wednesday. The plugs were removed,cleaned then i went for a run,came back and removed them+thats how you see them on the photos (sorry they are a bit big) i balanced the carbs with a carb balancer best i could but idle speed could not be maintained accurately, i have tried different leads, and from start up engine is lumpy,with a vibration and a definate miss or vibration on most rev ranges,mixture seem right when doing the lift pin test on the carb bodies
Smallfry,i had the inlet manifold off recently and all looked well with the cam in fact the internals of the engine as a whole are allmost spotless with no gunge but as you say on closer inspection! I will do a compession test tommorow. As an aside i have some replacement heads to go on which i have put up a couple of questions on "ideal heads" in mechanical if anyone can help on that one
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Post by Warwick on May 9, 2009 1:14:41 GMT
If you have a multi-meter, set it to ohms and compare resistance of similar length leads. ~ Vince While on the subject of multimeters - Everyone should have one. If you don't have you, you should invest in one. It isn't difficult to learn how to use one. If you don't have one and you can only justify buying one, buy a real one - an analogue meter. If you already have a digital meter, consider also buying a real one. Digital is fine and has its uses. They are very good for quick checks on voltage and current where you want to know precisely what the value is, and it is steady and the connections are perfect. They are also auto-ranging in many functions so you don't have to worry about which scale you are reading from and where to set the switch - in many instances. But, they are complex devices and the reading you see is derived from all sorts of computations and calculations. In other words, they read one thing and then interpret it as something else. Sometimes they lie. Sorry - a bit strong - they get confused. An old fashioned analogue meter says what it sees. A good example is when measuring resistance such as the plug leads or when checking earth connections. A digital meter will probably jump all over the place as it constantly tries to interpret the slight variations that occur while you are trying to get a good connection at the probes. In the same instance, the analogue meter will sit rock steady on the reading and all you have to do is make sure you read from the correct scale. It doesn't lie. |
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Post by enigmas on May 9, 2009 1:58:04 GMT
Eightofthem, if you did the freeway test, you would have needed to switch the engine off at speed (constant throttle....say 2400 rpm) and than coast to the side of the road to remove the plugs. if you allowed the engine to drop in rpm or idle or drove home...your reading of the plugs will be inaccurate.
None of the spark plug leads should (ideally) touch one another (poor insulation leads to cross-firing...and I presume you checked the distributor cap for cracks, tracking and earth-leaks.
On the subject of Electronic ignition systems. A while back I fitted a 'system' which was triggered by points (on my daughters car....1967 XR Ford). It could also be modified to use other triggers and incorporated dwell control through an adjustable trim pot. Well, what a pain in the butt! It started beautifully, idled well but wouldn't rev beyond 2300...as though rev limiter cut in. Under hard acceleration the engine would fade and fuel consumption became woeful. I returned the vehicle back to the original points (Kettering) system and it runs perfectly (another alternate version of electronic ignition will be trialled later).
Warwick ants got into my old analogue meter and it was...cactus! It was all those things you state. Do you know where to purchase a reasonably priced analogue meter?
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Post by johnwp5bcoupe on May 9, 2009 5:40:43 GMT
If you have a multi-meter, set it to ohms and compare resistance of similar length leads. ~ Vince While on the subject of multimeters - Everyone should have one. If you don't have you, you should invest in one. It isn't difficult to learn how to use one. If you don't have one and you can only justify buying one, buy a real one - an analogue meter. If you already have a digital meter, consider also buying a real one. Digital is fine and has its uses. They are very good for quick checks on voltage and current where you want to know precisely what the value is, and it is steady and the connections are perfect. They are also auto-ranging in many functions so you don't have to worry about which scale you are reading from and where to set the switch - in many instances. But, they are complex devices and the reading you see is derived from all sorts of computations and calculations. In other words, they read one thing and then interpret it as something else. Sometimes they lie. Sorry - a bit strong - they get confused. An old fashioned analogue meter says what it sees. A good example is when measuring resistance such as the plug leads or when checking earth connections. A digital meter will probably jump all over the place as it constantly tries to interpret the slight variations that occur while you are trying to get a good connection at the probes. In the same instance, the analogue meter will sit rock steady on the reading and all you have to do is make sure you read from the correct scale. It doesn't lie. That why I still have my old Avo 8 Warwick  |
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Post by Warwick on May 9, 2009 8:48:09 GMT
Sorry Vince, I still have the one my Dad gave me for my birthday in 1968. A Japanese Sanwa branded as a Rapar. Remember Radio Parts?
John, I hope you keep it in a Metercoon during winter - Avo; the Rolls Royce (or P5?) of multimeters!
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Post by Phil Nottingham on May 9, 2009 8:49:40 GMT
I have a 1958 Avo too plus an old hand cranked Mega
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Post by johnwp5bcoupe on May 9, 2009 9:18:11 GMT
Sorry Vince, I still have the one my Dad gave me for my birthday in 1968. A Japanese Sanwa branded as a Rapar. Remember Radio Parts? John, I hope you keep it in a Metercoon during winter - Avo; the Rolls Royce (or P5?) of multimeters! Yes I do Warwick they are Stable Buddies I also have a Mk7  I wont mention Phil's Hand Crank Mega  |
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miguel
Rover Fanatic
Posts: 462
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Post by miguel on May 9, 2009 13:53:02 GMT
I just bought one last month. Expensive and has a lot of functions.
Its DIGITAL!
NNNNNNOOOOOOOOOOOOOOOO!
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Post by Warwick on May 11, 2009 0:27:32 GMT
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