Have recently put my Javelin back on the road. The engine is running smoothly but won't exonerate past 50 mph. I have fitted a re con dizzy from the dizzy doctor with the Clements curve. Would the engine run if the dizzy was 180 deg out. The static timing is set at tdc on no 1 cylinder. It shows 10 deg btdc on tick over with a timing light. Could it be possible a bob weight has come off would this be the symptoms. I have also fitted re con carbs and vacuum pipe is ok.
Thanks for ideas Barry.
Timing
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Barry20383
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Keith Clements
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Re: Timing
There could be a few reasons.
With vacuum pipe disconnected you should get about 22 deg advance at 2500 rpm and with pipe connected another 10 deg with vacuum, by blipping throttle. But make sure you are measuring correctly and are using the correct TDC mark on flywheel.
Check wires are not trapped and stopping breaker plate from moving. You can check weights by releasing the two screws holding the plate. Check both springs are attached to weights.
Are throttles opening fully?
What else have you changed since it ran over 50mph?
With vacuum pipe disconnected you should get about 22 deg advance at 2500 rpm and with pipe connected another 10 deg with vacuum, by blipping throttle. But make sure you are measuring correctly and are using the correct TDC mark on flywheel.
Check wires are not trapped and stopping breaker plate from moving. You can check weights by releasing the two screws holding the plate. Check both springs are attached to weights.
Are throttles opening fully?
What else have you changed since it ran over 50mph?
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David Morris
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Re: Timing
Hi Barry,
Agree with all Keith advises. How did you set the static timing? I have found the flywheel marks, where they exist at all, to be unreliable. I would use a length of stiff wire inserted gently down the No.1 plug hole and check for the exact TDC position using the starting handle with care.
It sounds as if something is rev limiting and it may be nothing to do with the ignition. Rather than trying to drive at more than 50mph, does the engine rev freely when the car is static? It's a bit of a long shot, but try running the engine at full throttle at night and with the bonnet open. You may need a helper to do this? In the dark, you might see arcing from the ignition leads, the coil, or from the distributor cap?
Alternatively, are the carb jets clear and are the carbs balanced? Using a synchronmeter alternatively on both air intake tubes is what I have found to be the only reliable way to get them balanced.
Hope this helps,
David
Agree with all Keith advises. How did you set the static timing? I have found the flywheel marks, where they exist at all, to be unreliable. I would use a length of stiff wire inserted gently down the No.1 plug hole and check for the exact TDC position using the starting handle with care.
It sounds as if something is rev limiting and it may be nothing to do with the ignition. Rather than trying to drive at more than 50mph, does the engine rev freely when the car is static? It's a bit of a long shot, but try running the engine at full throttle at night and with the bonnet open. You may need a helper to do this? In the dark, you might see arcing from the ignition leads, the coil, or from the distributor cap?
Alternatively, are the carb jets clear and are the carbs balanced? Using a synchronmeter alternatively on both air intake tubes is what I have found to be the only reliable way to get them balanced.
Hope this helps,
David
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Barry20383
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Re: Timing
After a run there is a strong smell of petrol.On investigating i found both the bellows on both carbs wet on the inside with petrol.Seems like blow back the timing is set static TDC. Perhaps i need to retard the ignition as the spark is coming before the inlet valves are closing.
Thanks Barry.
Thanks Barry.
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Keith Clements
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Re: Timing
We have two or more threads which are confusing and need corelating.
You are in danger of chasing your tail.
Take a short video of the engine idling and either post on here or link to youtube.
Do the same with a short blip on throttle.
Take the carb bellows off and do the same.
If the engine idles and you have a DD dizzie it is unlikely to be ignition timing.
If there is no bark on the inlet track then it is unlikely to be valve timing.
If the plugs are grey it is unlikely to be mixture.
If the plugs are black then it likely to be the carb. I suspect it is the needle valves.
You are in danger of chasing your tail.
Take a short video of the engine idling and either post on here or link to youtube.
Do the same with a short blip on throttle.
Take the carb bellows off and do the same.
If the engine idles and you have a DD dizzie it is unlikely to be ignition timing.
If there is no bark on the inlet track then it is unlikely to be valve timing.
If the plugs are grey it is unlikely to be mixture.
If the plugs are black then it likely to be the carb. I suspect it is the needle valves.
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Barry20383
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Re: Timing
The car is fitted with a recon dizzy with Clements curve from the dizzy doctor.
It also has recon carbs from the Jowett spares.
Have checked the plugs they are dark grey.
Have noticed the car seems to be running cool about 60c
65C Is this normal it has a new 75c thermostat fitted .
Will now check the timing with a strobe light and rev counter have checked the bob weight springs they are still ok.
Barry.
It also has recon carbs from the Jowett spares.
Have checked the plugs they are dark grey.
Have noticed the car seems to be running cool about 60c
65C Is this normal it has a new 75c thermostat fitted .
Will now check the timing with a strobe light and rev counter have checked the bob weight springs they are still ok.
Barry.
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Keith Clements
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Re: Timing
Ah recon carbs....note these probably have not been tested after recon. There could be a blockage somewhere. If you still have the old carbs refit one by one.
I would check the jet sizes and gasket condition, float is free to move. Being grey plugs points to fuel starvation when on full load. Does it hesitate to accelerate?
Also listen with tube to ear around carb body for leaks.
A video would help diagnosis and save you a lot of time.
I would check the jet sizes and gasket condition, float is free to move. Being grey plugs points to fuel starvation when on full load. Does it hesitate to accelerate?
Also listen with tube to ear around carb body for leaks.
A video would help diagnosis and save you a lot of time.
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Barry20383
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Re: Timing
Dont have the old carbs as given to JCS as exchange.
The car seems to pull up hills ok in top or third gear and revs ok out of gear. In top it exelerates up to 50 then stops at that speed and won't go any faster but seems happy. Have opened the dizzy plate and the bob weight springs are in place .
Have checked the timing with a strobe light and rev counter. With vacuum pipe off and engine set at 1200rpm found firing plus 20 dbtdc reset back to 15btdc.
With vacuum pipe connected set engine speed to 600 rpm now firing at TDC at this speed.
Engine popping a little if reved hard.
Have video but don't know how to put it on this site.
Barry.
The car seems to pull up hills ok in top or third gear and revs ok out of gear. In top it exelerates up to 50 then stops at that speed and won't go any faster but seems happy. Have opened the dizzy plate and the bob weight springs are in place .
Have checked the timing with a strobe light and rev counter. With vacuum pipe off and engine set at 1200rpm found firing plus 20 dbtdc reset back to 15btdc.
With vacuum pipe connected set engine speed to 600 rpm now firing at TDC at this speed.
Engine popping a little if reved hard.
Have video but don't know how to put it on this site.
Barry.
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Keith Clements
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Re: Timing
Only short videos can be loaded as attachment on JT. Best to load to Youtube and copy share link in JT post.
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Keith Clements
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Re: Timing
Check both throttles are fully opening.
What is max speed in third on the flat and up a slight incline? Would not rev above 5500.
What is max speed in third on the flat and up a slight incline? Would not rev above 5500.
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David Morris
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Re: Timing
Hi Barry,
I wouldn't rev her beyond 5500 anyway! Not only would you be entering valve bounce areas, but she's 70 years old, so don't push her too hard!
Age may only be a number and they say age brings experience, but there are limits!
Bristol council say that 20mph is safer than 30mph and slower is better. This applies to many things, so take it easy and enjoy the ride!
Stay safe,
David
I wouldn't rev her beyond 5500 anyway! Not only would you be entering valve bounce areas, but she's 70 years old, so don't push her too hard!
Age may only be a number and they say age brings experience, but there are limits!
Bristol council say that 20mph is safer than 30mph and slower is better. This applies to many things, so take it easy and enjoy the ride!
Stay safe,
David