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Complete lack of power under load, V8 Saloon.

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Alpine Daimler
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Location: A tad west of Hamburg on the Elbe River

Complete lack of power under load, V8 Saloon.

Post by Alpine Daimler »

At last my turn to look for help with a problem!
I've had my V8 saloon a couple of years now and has always run well.
About last Oct/Nov I started with winter refit which because of underestimating the work and taking on a little too much, overestimating my ability to work quickly and work commitments I finished last week and discovered the problem, no challenge, mentioned in title of post!
It might help to mention I performed the following tasks :
-Removal of carburettors and inlet manifold, replacement of heater tubes after clean up of tappet chest etc. All gaskets renewed and that short hose from inlet manifold to brake servo pipe renewed....which was in a dire state, all orifices were blanked off and carbs bagged up and kept stored upright
-Removal, dissassembly and complete overhaul of heater.
-Removal and overhaul of main and lower steering column including switch gear (blinker/flasher and overdrive) horn ring etc.
-Fuel filter bowl to carbs fuel feed pipe replaced with modern braided steel type, flter sieve cleaned.
-Distributor cap, rotor arm and all leads cleaned, contacts of leads checked for integrity etc, points lightly cleaned, gap checked.
-New plugs fitted, checked for sparks seems ok.
-Carb dash pot cylinders topped up with 20/50 engine oil
When trying to start for first time it took a while but eventually kicked in and with a little help from throttle and choke. Ran well at idle, a test run prooved all was not well.
I discovered I had forgotten to connect (or it had come offf during heater refit struggle!) one of the mixture control rods to one of the carbs, not connected the dynamo or the vacuum pipe from inlet manifold to distributor, this incidently came off twice more untill I re-bent tube to ensure it stays put!, having put these things right I am now charging the battery and it idles and starts much better!!!
The engine starts and idles well and revs freely to 3000 rpm without complaint, sounds v good actually, i was convinced the complete lack of pulling power on the road was down to the vacuum pipe not being connected, sadly that does not appear to be the case, when I apply almost full throttle there is no miss-fire just no fire! Smoke or unburnt fuel does not bellow out the back or anywhere else does so far I can tell.
Any ideas where I should look next? As always very grateful for any input.
Regards
Rob c.

Ian Slade
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Re: Complete lack of power under load, V8 Saloon.

Post by Ian Slade »

Check the distributor advance mechanism is working, with the points plate removed you can see the springs and weights, with the rotor arm in place you should be able to turn the rotor and shaft a small amount and watch the weights fly out. Should you not be able to do this the top shaft has seized to the drive shaft and requires freeing off.
Owner since the 70's, Genghis is slightly to my left.

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Alpine Daimler
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Joined: Thu Feb 18, 2016 2:17 pm
Location: A tad west of Hamburg on the Elbe River

Re: Complete lack of power under load, V8 Saloon.

Post by Alpine Daimler »

Thank you for your response Ian.
I have tried moving the rotor arm whilst installed into shaft and have some movement there but it does not return by itself.
I shall try removing the base plate tomorrow and see if the weights move, does that involve removing the screws and springs parts "19" as illustrated in fig 6 on page P13 of manual and will the points come away securely fitted to the base plate "all in one" or do they have to be removed first?
Many thanks and all the best down there in the Med!
Rob C.

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Re: Complete lack of power under load, V8 Saloon.

Post by Ian Slade »

I can't remember the exact process as my books are still in the UK with the car and my son, I seem to remember you have about a 1/4 turn and you give it a quick flick, with the points plate removed you will see the weights and springs, if they don't fly undo the screw in the shaft under the rotor arm. This is a known problem on all old engines without electronic spark advance, it can even happen during use let alone after a lay up, lubricate with engine oil or lithium grease.
Owner since the 70's, Genghis is slightly to my left.

Fossil
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Re: Complete lack of power under load, V8 Saloon.

Post by Fossil »

As corroboration, a story from the distant past.

During my years as a student in the late 60s I owned a series of Conquests and Centuries (not all together), largely because they were comfortable and inexpensive. But the discovery that they were suited to owner maintenance started this whole car enthusiast thing. One of the Centuries was curiously sluggish compared to the others, and to cut a long story short I found that the distributor weights were seized. Freeing them up resulted in the most wondrous improvement in performance in any one machine that I can recall. It gave that incomparable broad grin feeling that we all love so much.

Another potential cause of similar trouble is a punctured vacuum advance capsule rubber membrane. This can be checked simply by applying suction to the manifold end of the pipe, even with the mouth, which should result in clear movement of the contact breaker base plate. If there is no movement refurbed capsules are available on an exchange basis from the usual suspects, for example the Distributor Doctor, or Holdens I think. Something that any car of that age should have done now if it hasn't been done before.

Regards

Geoff

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Alpine Daimler
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Location: A tad west of Hamburg on the Elbe River

Re: Complete lack of power under load, V8 Saloon.

Post by Alpine Daimler »

Thank you Geoff, your response and sound advice are also appreciated.

Right, by applying not too much light machine/lubricating oil by means of a long nozzle under the base plate I seem to have quite possibly freed off the centrifugal weights as when I turn the shaft untill its stop (about 15-20°) and release I can hear something flicking around under there and it now returns smartly to its original position.

Due to other every day life commitments I have been unable to test drive yet, its stationed away from where I live which also does'nt help!

On my next visit to my workshop I shall try removing the screw Ian describes above and check freedom of movement of top shaft as I read his post first on my return from completing the tests and repairs described here!

I tried testing the vacuum capsule by the method you describe ...no movement of capsule operating rod and base plate but vacuum was easily maintained, there appears to be no leak. I tried moving the base plate with operating rod still attached and it moves freely and returns over what appears to be it's entire range, whats wrong there? is the membrane ok but something siezed?

To finish if I , or anyone else, wishes to remove the base plate it would appear the operating rod from vacuum capsule will first have to be dissconnected from the base plate, but how? is it just slipped over the underside of the pin shown in this photo of my distributor attached which, incidently, is still installed as I recall reading somewhere on the old forum the removal of which is not to be undertaken lightly.
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20170714_123744.jpg

Chris_R
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Re: Complete lack of power under load, V8 Saloon.

Post by Chris_R »

I would suggest that you look at the areas you touched. Carburetors, fuel filter and distributor. Others have mentioned distributor but lack of power could also be shortage of fuel. Check the carburetors are working as they should be. They're SU's aren't they? I'm not familiar with these so can't give any specific suggestions. Float levels? Dash pots lifting correctly? Is the filter allowing enough fuel to pass?

Christopher Storey
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Re: Complete lack of power under load, V8 Saloon.

Post by Christopher Storey »

The vacuum capsule attaches to the moveable baseplate via a spigot on the base plate. there are two varieties of attachment, and I cannot remember which our distributor has. The more usual one is a heavy spring with a loop on its end ; the loop slides over the spigot, and can easily be attached /detached once the baseplate assembly is unscrewed from the distributor body. The less usual type is a solid arm which can float up and down a little to give flexibility, again with a hole at its end which fits over the spigot

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Re: Complete lack of power under load, V8 Saloon.

Post by Fossil »

Robert

Settling down to start my reply for the second time...........the first attempt ended when my Firefox screen abruptly disappeared!

As Chris says the vac capsule is simply connected to the baseplate by the springy thing visible in your photo. If that doesn't move when suction is applied, it is defective, and the capsule probably needs to be refurbed, although I've never encountered that situation; normally when you suck, either the thing moves or you just suck in air through the perforated diaphragm. Perhaps it is just rigid but not holed.

Re the distr. cam screw, I suggest that you first remove the top body by removing the three screws and springs, but take great care not to drop these. Once released the top body slides up over the cam revealing the magical "centrifugal governor" below. I only have an SP250 manual so I cannot confirm the illustration reference that you quote. Take a clear photo of the two weights and their springs, it is essential that these go back where they are. Then remove the cam screw and slide the cam up off the shaft, noting where the cam bottom plate engages with the two weights. Remove the weights and do not lose the two springs, then clean everything thoroughly. If the cam was seized or stiff on the shaft, or if the weight pivots were tight pay particular attention to them to remove any corrosion, dirt, hardened grease or whatever with a solvent such as white spirit, but don't let neat solvent drip underneath the weight assembly to the bearing. Check whether there is any play in the shaft/bearing assembly. If all is well with no play anywhere then reassemble all with care and the application of limited amounts of grease at the pivot points. Slide the cam back on to the shaft ensuring that it reconnects correctly with the weights and replace the screw. Put a few drops of clean engine oil on the screw. Now if the cam is rotated back and forth the weights should move out and back in freely. If so then return the top body to its rightful place, engaging with the micro-adjuster screw at the front, and replace the three spring loaded screws. Fit the refurbished vacuum capsule to the near-side of the top body, and apply vacuum to check that the plate moves; I should have said to apply some engine oil to the felt pad on the underside of the top body before it is replaced, to lubricate the base plate. Alternatively you can remove the circlip and spring to separate the base plate from the body and clean it all thoroughly too.

It is perhaps not surprising that all of the foregoing is much easier if the distr. is off the engine and on a bench or table so that you have a more comfortable position and good light to do everything. The replacement of the distr. on the engine is relatively straightforward provided that you have set the crankshaft at 10 degrees before TDC before removing it; then it is just a matter of ensuring that the offset tongue of the distr. drive shaft engages correctly with the offset slot in the camshaft oil pump/distributor drive gear. Given what you have done already getting to know your distributor should just be another pleasant step on the journey of discovering the magnificent Daimler V8.

Clearly though if you do find wear of a significant nature at any of the pivots or the shaft to cam or shaft bearing then the entire unit will need to be exchanged for a restored example, and it would be worthwhile comparing the cost of this from Barry T, The Distributor Doctor, S N G Barratt, D Manners, etc.

Re checking the SUs, I suggest that you simply remove the dash pots, check that the springs are intact and after removing the dampers and draining the oil from the pistons, check that they move freely in the dashpots; clean them and the insides of the dashpots with a lint-free cotton cloth. To check the fuel level in the jets while the dashpots are off I often just blow briefly at them, a sharp puff; if the fuel level in the float chambers is correct the puff of air will push the fuel down briefly and it will then return rapidly and overflow slightly from the jet. If it doesn't do this, or if you can see fuel on the outside of the jet without any disturbance, the float chamber lids will need to be removed and the floats checked and levels reset.

Another long post I'm afraid

I hope that it helps.

Cheers

Geoff

Christopher Storey
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Re: Complete lack of power under load, V8 Saloon.

Post by Christopher Storey »

Robert ( and Geoff) : just thinking further about the vacuum capsule situation, I suppose there is one further possibility, and that is that the moveable part of the baseplate has seized in the fully advanced position . This would explain why there is no movement, and yet the diaphragm in the capsule appears to be intact . If that is coupled with seized advance weights, ( giving no mechanical advance ) it could possibly explain why the engine runs up to 3000 rpm but then will go no farther

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