Joined: Jun 2018 Posts: 65 Threads: 14
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Location: Kenilworth, Warwickshire
04-04-2022, 08:40 AM
(This post was last modified: 04-04-2022, 08:40 AM by fatcatvera.)
I'm having an issue with my Ruby engine running - it has become rev limited. Though the car is completely driveable as it is I can no longer acheive higher engine speeds (cannot state rpm as no rev counter!). It doesn't seem to be fuel related as the carb and fuel syetm is spotlessly clean, nor the rest of the ignition system and I've also tried a few coils without resolving the problem, so I'm suspecting the devils own confusing thing that is known as the condensor....can a failed/failing condensor cause these symptoms? I've had a go at removing the condensor completely, but this causes very difficult starting and extremeley poor running.
The other alternative is that I'm hitting the limit of valve bounce, but it 'feels' like I should be well below that threshold.
Thanks
Ray
Joined: Aug 2017 Posts: 926 Threads: 22
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Location: Near Cambridge, UK
Car type: 1928 tourer (mag type), short chassis Gould Ulster
I think the only effective test is to substitute a new one, or at least a known good one from an engine which runs without the fault. They are not expensive.
Joined: Aug 2017 Posts: 557 Threads: 89
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Location: Deepest darkest Kent
You can do an insulation resistance test on a condenser to find out if it is faulty.
Joined: May 2018 Posts: 2,108 Threads: 110
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Location: Llandrindod Wells
Car type: 29 Special, 30 RK, 28 C Cab
Hi
A few modern digital multimeters have a condenser test setting which gives a read out in mFarad.
Cheers
Howard
Joined: Aug 2017 Posts: 2,748 Threads: 31
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Location: Auckland, NZ
Low voltage checks of condensers do not prove much. Usually either produce a spark or not. Retarded or lack of spark advance will limit revs but usually evident as a flat sound and surging accel at higher speeds. Does the rotor feel normal when twisted? Is throttle opening fully?
Valve bounce revs exceed 40 mph in 3rd so unlikley unless a broken spring.
On another make I had a silencer baffle come loose. Severeley reduced performance but esp speed.
Joined: Aug 2017 Posts: 782 Threads: 26
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Location: On a hill in Wiltshire
You can add another condenser externally, just to check.
I go to my local car spares place and buy any condenser with a wire lead at one end and a mounting tag at the other.
The wire goes on to the connection on the dizzy and the tag tucks under a cylinder head washer.
If the car's running improves - you know what the problem is.
Joined: Aug 2017 Posts: 1,715 Threads: 47
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Location: Auckland NZ
Car type: 36 Nippy, 31 RM, 38 Special, 24 Works Rep
Have you checked the obvious and ensured that the throttle butterfly is fully opening?
Black Art Enthusiast
Joined: Jun 2018 Posts: 65 Threads: 14
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Location: Kenilworth, Warwickshire
Thanks for the feedback. I've got a new A-series lucas condensor to hand that I can try, so will give that a go mounted externally and see what the effect is.
Ray
Joined: Aug 2017 Posts: 1,193 Threads: 71
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The late Ray Walker, whenever he looked at the perfromance of an Austin 7, would get the owner to sit in the car and depress the throttle pedal to its maximum. Then he would see if he could get further movement on the butterfly at the carb. It's a test well worth doing, with sometimes surprising results...
Joined: Dec 2017 Posts: 1,160 Threads: 68
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Location: Nottinghamshire. Robin Hood County
Car type: Austin Ruby Mk1 1935
I have a spare A7 condenser wired up with two fly leads with crocodile clips. One to the body and the other to the terminal. All well insulated with tape. I carry it as a spare and it can be clipped on if required without removing the exsisting condenser. It is also good for testing out suspect condensers.
John Mason.
Would you believe it "Her who must be obeyed" refers to my Ruby as the toy.