running very rough !

[Deleted]

I entered the forum a couple of months ago for some much needed advice on my newly acquired 3.5 saloon.
I struggled for quite a while and ended up fitting -
New electric petrol pump.
new plugs and plug leads
new points and condensor
new carb jets and needles
new float chamber inlet valves
new gaskets all round
I set everything up as advised and I was thrilled when it burst in to life and ran extremely well. Better than I had hoped. I even took it for an illegal run up the road. On top of the smaller bits I also fitted a re-con radiator, all new hoses, flushed it out etc etc etc.,
I was very happy and I began to attend to other jobs.
However !!! One day about 3 weeks ago I started it up and let it run for a while to warm up and everything was fine. It was ticking over very nicely. Suddenly it stopped. No noise - it just stopped., and no matter what it wouldn't start again. It tried - it fired - but it wouldn't run. It was erratic and all over the place.
I went through all the usual checking and testing - fuel, ignition, timing, everything. Why did it just stop ? 3 weeks later and I'm still none the wiser. I've spent hours on it. I removed the carbs and went through them precisely. I reset the timing precisely as per the book and double checked time after time. I did a compression test on every cylinder -
perfect - 200psi in every one. I changed the coil, I put the old leads back on etc etc. Now I've given up. All my experience and I'm none the wiser. No matter what I do absolutely nothing makes any difference. I don't have the slightest clue to help.
I knew that if I came back on the Forum for help that all you guys would repectfully suggest that I try this and try that, and I knew that wouldn't help. It really needs someone standing beside me to see the problem.
So, tomorrow morning I've got a recommended mobile engineer coming who has an electronic analyser on his van, and he assures me that he will pinpoint the problem.
Watch this space !!!

[Phil Nottingham]

Coil - have you checked you have a spark, if not failed coil, faulty wiring, wiskered points, faulty condensor - new does not mean good! Centre contact in dizzy cap fallen out?
Fuel - are the float chambers full?

Stale/contaminated petrol?

[harvey]

Electronic analysers are only as good as the person that's using them, and don't do anything you can't do without them.

[Deleted]

Thanks Phil, but I knew you would go over ground already tried several times over. I changed the coil, I checked the spark at the plugs, I swapped the dizzy cap with my son's car, I drained the carbs and filled the chambers with fresh petrol, .................................... etc. Believe me, after 3 weeks I wasn't able to do one thing that changed anything or provided a clue. I hope tomorrow will reveal the problem.
Mike

[Deleted]

Sorry Harvey, whilst I appreciate your comment I don't agree with you.

[harvey]

Ask your man when he comes what his machine can do that I can't with a decent tool kit.

[Phil Nottingham]

We look forward to hearing from you when sorted then?

[RichardF]

Classicgrendogs, where abouts in the country are you? One of us might be near enough to assist if the engineer can't help.
Best of luck
Richard
Southampton

[Deleted]

Hi Harvey, A machine can and does analyse all the things that are going on SIMULTANIOUSLY.
It can see where the interaction is going wrong between fuel, spark, and engine and it shows you immediately. A mere human can only look at one thing at a time and then try to make a judgement.
I've used analysers many times and never found one that was wrong.
Hi Richard, Many thanks for your kind offer. I'm in Norwich in Norfolk. I would say to everyone that the guy with the analyser is a very experienced classic car man in his late 50's, recommended to me by the Norwich Rover owners Club.
Thanks to everyone for the nice comments.
Mike

[harvey]

You pays your money you takes your choice........

[Phil Nottingham]

These are the stock answers you have been given and no engine has beat me yet but there is always a first time. Sometimes an engine overheats so that oil disappers and the rings stick - I have towed cars to start them but unfortunately this is not an option with P5B's

At least you analyser chappie is of mature years so he may have some other tips which I hope you pass on especially if he does sort it.

Its still odd that you have not picked it up but now and I agree basically with Harvey's views but there is obviously something amiss. Someone on the scene may be the key.

Has it got the AED still although if its still making an attempt to fire it may be that the valve timing has slipped - this is possible though unlikely. Has any work been done on this or was there any sign of slack timing chain - are all the valves opening sufficently and is oil pressure building up on cranking ie the green light goes out?

How are you are setting the ignition timing - these dizzies turn clockwise it may sound obvious but sometimes it is the obvious.

A simple thing like the ignition switch or ballast bypass not working can prevent a spark when cranking the engine? Corrosion of the dizzy earthing screws?

Good luck anyway

[Deleted]

Thanks Phil,
I confess I am mystified. Part of the problem is that I appear to be a long way away from
other members, so I miss the second opinion first hand. I contacted the local Rover Owners Club to see if they knew of anyone in the area who might come and have a look. One guy said he would, but I could tell he wasn't keen. In answer to your points, no it doesn't have an AED. I thought about valve timing, but I get no 'kick-back' when cranking, and I get no spitting, no back firing etc., Yes, the oil light goes out OK, and the engine cranks up around 35psi on the gauge. I dilligently set the timing as per the manual, and checked the firing order umpteen times. I put a spark plug where I could see it, and observed a healthy spark. Part of the mystery is that it was running OK one minute and not the next. Going professional seems the best option. I'll let you know what happens.
regards,
Mike

[Deleted]

After all these years I should have known better !! You were right Phil. Fitting new components is no guarantee. The analyser picked up the problem instantly. The 'brand new' condensor I had fitted was KAPUT ! I had bought new points together with a new condenser and everything seemed fine. But clearly it wasn't, and the condenser broke down and caused havoc with the spark. I never expected it, and it has never happened to me before. The analyser also told me that the butterfly on the right carb needed replacing and the wear made it difficult to balance the 2. It is quite severe. Also the needle valve I had replaced in the left float chamber wasn't working, and it was pumping petrol out of the overflow.
We fitted the old condenser - reset the carbs as well as possible and re-fitted the needle valve. I'm now back to square one again thank goodness. The moral has to be -don't assume new components are foolproof ! We also re-set the timing and the dwell etc., which seems so easy to do using the analyser. (Psssst ! Anyone want to buy a P5 ?)
Mike

[Phil Nottingham]

Thanks for keeping us updated - I have been caught by faulty new components a number of times now and its happening more frequently

[dorsetflyer]

Now that's all settled, it might be worth thinking about 'Electronic Ignition', it should save all the hassle.

[Deleted]

You're right John. It's definately on my list of 'to do's'
regards,
Mike

[Colin McA]

Was this guys ANALyzer like a fancy multi meter.

I bought a ANALyzer which is a good multi meter with engine functions, it may do temp aswell but how could it work out that the butterfly was worn?

Colin

[stantondavies]

Watch your spelling arthuy!!!

[Deleted]

Hi Arthuy,
He connected something to each air intake and it showed a massive imbalance left to right.
The wear on the right butterfly screws allowed the pressure to open it which could clearly be seen on the oscilliscope. I thought each carb only fed the cylinders on the side it was mounted - not so I was told.
The left feeds some on the right and the right feeds some on the left. Other than that he adjusted the mixture in the old fashioned way by lifting each needle and moving the jet up or down until it was right.
Following that the Oscilliscope showed the reaction of each spark plug to the new set up and a nice balance was reached. He was able to minimise the effect of the butterfly problem, but it still needs doing.
regards,
Mike

[Phil Nottingham]

Yes its a common misconception about one-sided carb manifolds - they are arranged like this on V8's to give as far as poss equal inlet tracts.

The throttle spindle leak would have shown up on any carb balancer device - electronic devices are better for showing up worn dizzies which the early type used up to Autumn 72 is very prone to .