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Vitesse Mk2 engine running issue


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Hi All
I’ve recently joined the TSSC and I’m hoping that someone can assist me.
I have a 1969 Vitesse Mk 2 that, as far as I can tell, is pretty standard. However the engine hesitates/surges between 2000 and 3000 RPM, which is most noticeable when accelerating (even gently) in 2nd gear. 
Also, occasionally when travelling at a contact speed on a flat road, say at 55 MPH, the engine seems to start to loose power for a few seconds and then makes a ‘phutt’ sound, then resumes normal power.
I have tried different dashpot oils(3-in-1, SAE 10 and 20-50) but none seems to make any difference.
The timing has been checked with a strobe light and it is OK. The ignition advances with increasing revs.
New sparkplugs have been fitted.
A new fuel pump has been fitted.
The points have been replaced with the magnetic sensor set-up, so no condenser needed.
I have tried to set the fuel-air mixture using two of the Gunson Colourtune spark plugs in positions 2 and 5, but with little success.
The carbs have new diaphragms and O-rings fitted to the main jets. I have followed the manual for the resetting of the main jets using the lifting pins on the carbs., etc.
It starts well from cold, but starting can be problematic when the engine is warm.
The temperature gauge reads just below the half way mark when fully warmed up. Note: The hesitation is still there when the engine is cold, so it doesn’t seem to be related to the engine temperature.
I have searched this forum for ‘misfire’ etc.
Thanks in advance.
SteveT
 

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have a look at the dizzy cap is this a delco dizzy ????   make sure the cap centre contact is actually touching the sprung contact of the rotor arm

if its a lucas and the rotor has a rivet in the sweep plate throw it away get a red one from club shop or others 

what plugs/type  are you using ?

dashpots  are straight 20 or engine oil 20/50 dont mess with others 

as you have fitted a pump and played with the carbs there is a good chance refitting rubber hoses has made some of the dreaded rubber slivers

which float about and jam up the back of the float needle valve ( persistent little sods ) 

does it have std air filters and air box ??

make sure no filter gaskets are covering any front face holes in the carb 

any corrosion up the coil HT connection ??  and check the coil polarity  ie neg to dizzy   white ign to Pos

what was the trouble with the colour tune , good result /no result

what did the lifting pins show ???

that do for a start 

Pete

 

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Hi Pete,

Thanks for your prompt reply. The distributor rotor arm is the new(red type). Plugs are NGK BP6ES. Air filters are standard. Will check the other points you mentioned also.

Thanks again.

SteveT

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Lucky lucas are the best

do check the dizzy has a moving plate short braided earth lead to one of the plate fixing screws  often these break inside the braiding and you get an intermitent earth 

always give a squirt of oil under the base plate to oil the top dizzy bearing or it wears out and the shaft wobbles and the gap becomes variable as the cam rotates 

so give the rotor spindle a good sideways shove , it should not move 

Pete

 

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Hi Guys,

Its probably something I've done. Just after I acquired the car, I found it had a bad oil leak coming from the rear of the cylinder head; while I had the head and carbs off, I replaced the carb O-Rings(that had gone hard and were breaking up) and the diaphragms. Just after that, I found that the fuel pump was sucking in air under the bolt that holds the metal cap on, as I couldn't successfully seal this, I fitted a new pump, along with a new fuel line to the carbs. I also replaced the points with the magnetic sensor setup about the same time, and reset the timing with a strobe light. I also fitted a thermostat as the previous owner hadn't fitted one('It always ran cold', he said). The temperature is now fine and the needle is just below the half-way mark when fully warmed up, but it hesitates/surges when cold also.

It's not so serious that I can't drive it, but I am concerned that it's not doing the engine/transmission any good.

I will check the distributor and the other suggestions this weekend. 

Thanks again for your assistance.

Steve T

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Hi Guys,
Over the weekend I checked the distributor shaft and there’s virtually no side play and the advance retard mechanism was free to move, but I put a few  drops of oil on it anyway. I also dismantled both carbs to check the float needle valves, both were clean, move freely and importantly they sealed well when closed. Jets were clear and I have centralised the main jets and set the jet adjustment back to the default setting(3 turns ACW). Will start it up later this week and try to fine tune the mixture using the lifting pins, etc.

Cheers,
Steve T
 

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Update: I stripped down the carbs down on the Vitesse at the weekend and re-centralised the main jets, etc. It seem to be going better now (not perfect yet) but the acceleration is now quite good. I took it out this lunchtime for a 20 mile run, so I now need to check the colour of the plugs to see where the mixture is, after I reset everything back to the default settings. It starts easily hot or cold now, so it can't be far away.

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I read you replaced the diaphragms, were they Durex flimsy? Or the dread elephant condoms? There are some awful spares out there. Did you take the carbs off the head? Manifold gasket leaks can be troublesome.

Doug 

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On 08/04/2021 at 17:28, Steve P said:

I would also check the fuel pipes haven`t degraded and are allowing air in somewhere,i had a similar issue on my Herald.

Steve

Hi Steve, I had right problems setting the carb on my 13/60 could never get it quite right. On your advise checked the fuel line and the rubber pipe before the carb was degraded and letting air in. Replaced that and added an inline filter and it's now perfect. Great post thank you. Cheers Martin

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Hi Doug, Interesting that you should mention the thick and useless diaphragms. About 2 years ago I purchase a pair from a very well know Triumph spares supplier and found that they didn't allow the slide to drop down, even with the jet block removed. I measured the new ones and they were 25 thou thick and the originals were only 15 thou thick. The supplier did replace them FOC however.

Hi Steve P & Martin, The fuel lines and rubber interconnections have been replaced and there were no signs of any deposits in the float bowels.

The hesitation and surging only occurs occasionally now and the car is generally going much better, but I will have another go at the set-up at the weekend.

Thanks,

Steve T.

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I set the mixture using the carb’s lifting pins and took the Vitesse out for a 20 mile run. It almost ran almost perfectly and only hesitated/surged once when accelerating in 2nd gear. When I got back I turned off the engine, opened the garage door and 5 minutes later it refused to start. Engine turned over fine with the new Bosch battery fitted last year.

Any ideas?

Is it worth fitting carburettor shields to reduce evaporation of fuel?

Thanks,

Steve T.

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43 minutes ago, SteveT57 said:

Is it worth fitting carburettor shields to reduce evaporation of fuel?

Not really, I've been through the hottest of summers in a GT6, a car famed for being on the edge of overheating. it's never happened. It can happen in sunnier climes, but not in UK in April. :lol: 

Doug

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24 minutes ago, Badwolf said:

Simple layman's terms

hic up  sort of miss you get when a spark plug is failing  you get a short  jerk on load ( not the driver)

die    power drops off  you start to panic

surge   takes off of its own accord  you get all excited 

on choke means you left the handbag hanging on the choke knob

does that help    Ha 

Pete

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Hot/warm starting issue:

I made another test run today, only about 8 miles this time. When I got back, I turned off the ignition and I was able to restart it immediately, twice. I left it 10 minutes and it refused to start. The carb float bowls and fuel pipe from the pump were only just warm, so its unlikely that it’s fuel evaporation from either of those areas. However the inlet manifold was very hot, so I got some damp rags and put them on the manifold to cool it down, but it still refused to start for almost 2 hours. Spark plugs looked OK, perhaps a bit on the rich side, so have screwed in the main jets by ½ a turn to lean the mixture. I will try another run this week

Frustrated of Rutland.

Steve T.

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